| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Departments of 1 Neurosurgery and 2 Pharmacology, Kyoto University Faculty of Medicine, Kyoto 606-8507, Japan
 |
ABSTRACT |
|---|
 TOP
 ABSTRACT
 INTRODUCTION
MATERIALS AND METHODS
RESULTS
DISCUSSION
REFERENCES
|
|---|
Endothelin (ET)-1 activates two types of Ca2+-permeable nonselective cation channels (NSCC-1 and NSCC-2) and a store-operated Ca2+ channel (SOCC) in rabbit internal carotid artery (ICA) vascular smooth muscle cells (VSMCs) in addition to the voltage-operated Ca2+ channel (VOCC). These channels can be discriminated using the Ca2+ channel blockers SK&F-96365 and LOE-908. SK&F-96365 is sensitive to NSCC-2 and SOCC, and LOE-908 is sensitive to NSCC-1 and NSCC-2. On the basis of sensitivity to nifedipine, a specific blocker of the L-type VOCC, VOCCs have a minor role in ET-1-induced mitogenesis. Both LOE-908 and SK&F-96365 inhibited ET-1-induced mitogenesis in a concentration-dependent manner, and the combination of LOE-908 and SK&F-96365 abolished it. The IC50 values of these blockers for ET-1-induced mitogenesis correlated well with those of the ET-1-induced intracellular free Ca2+ concentration responses. These results indicate that the inhibitory action of these blockers on ET-1-induced mitogenesis may be mediated by blockade of NSCC-1, NSCC-2, and SOCC. Collectively, extracellular Ca2+ influx through NSCC-1, NSCC-2, and SOCC may be essential for ET-1-induced mitogenesis in ICA VSMCs.
endothelin; calcium ion channel; cell proliferation
| |
INTRODUCTION |
|---|
|
TOP
ABSTRACT
INTRODUCTION
MATERIALS AND METHODS
RESULTS
DISCUSSION
REFERENCES
|
|---|
ENDOTHELIN (ET)-1 is a potent vasoconstricting peptide with a long duration of action (20). However, studies have indicated that it also possesses multiple additional biological activities. Among the diverse actions of ET-1, its mitogenic properties have attracted much attention because they indicate a possible role for this peptide in the pathogenesis of certain clinical conditions such as hyperlipoproteinemia or atherosclerosis (8, 13). Moreover, ET-1 plays an important role in neointimal hyperplasia after balloon-induced vascular injury, including that of the carotid artery (1, 3). The ability of an ET type A receptor (ETAR)-specific antagonist to block the mitogenic activity of ET-1 has been demonstrated (1, 17), suggesting that ET-1-ETAR interaction is necessary for the mitogenic action of ET-1.
It is generally accepted that extracellular Ca2+ influx plays a critical role in growth factor-induced cell proliferation (18). Moreover, extracellular Ca2+ influx via nonselective cation channels (NSCCs) is important for the growth factor-induced mitogenic response in mouse fibroblasts (12). However, it remains unclear whether Ca2+ influx is essential for ET-1-induced mitogenesis of native vascular smooth muscle cells (VSMCs), and it is equally unclear what types of Ca2+ channels are involved in mitogenesis in native VSMCs. These uncertainties are mainly attributable to the lack of specific Ca2+ channel blockers. Therefore, we attempted to pharmacologically characterize the Ca2+ channels activated by ET-1 in internal carotid artery (ICA) VSMCs using the Ca2+ channel blockers SK&F-96365 and LOE-908 (4, 14). ET-1 binds to its receptors and induces a biphasic increase in intracellular free Ca2+ concentration ([Ca2+]i) consisting of a transient peak and a subsequent sustained increase (11, 15). It is generally accepted that the sustained increase in [Ca2+]i requires the persistent entry of extracellular Ca2+, whereas the transient increase results from mobilization of Ca2+ from the intracellular Ca2+ store (6). We recently showed (11) that the ET-1-induced sustained increase in [Ca2+]i within A7r5 cells, which are cultured thoracic aorta VSMCs that predominantly express ETARs, is the result of Ca2+ influx through voltage-independent Ca2+ channels (VICCs) in addition to voltage-operated Ca2+ channels (VOCCs). These VICCs (associated with ETARs) consist of two types of Ca2+-permeable NSCCs (designated NSCC-1 and NSCC-2) and one store-operated Ca2+ channel (SOCC) (11). In particular, we demonstrated that these channels can be discriminated by using SK&F-96365 and LOE-908. That is, NSCC-1 is sensitive to LOE-908 and resistant to SK&F-96365, NSCC-2 is sensitive to both LOE-908 and SK&F-96365, and SOCC is resistant to LOE-908 and sensitive to SK&F-96365 (11). Thus SK&F-96365 and LOE-908 may be useful to identify which Ca2+ channels are activated by ET-1 and which Ca2+ channels are involved in ET-1-induced mitogenesis in ICA VSMCs.
| |
MATERIALS AND METHODS |
|---|
|
TOP
ABSTRACT
INTRODUCTION
MATERIALS AND METHODS
RESULTS
DISCUSSION
REFERENCES
|
|---|
Preparation and primary culture of ICA VSMCs for whole cell recording and monitoring of [Ca2+]i. Isolated VSMCs were prepared from rabbit ICA as described previously (5, 10, 15). Briefly, male Japanese White rabbits, each weighing 2-3 kg, were anesthetized by an intravenous injection of thiopental sodium (20 mg/kg) and killed by exsanguination. The ICA was removed, cleaned of surrounding tissues, dissected into small strips (2 mm × 5 mm), and kept in Ca2+-free Krebs-HEPES solution containing (in mM) 140 NaCl, 3 KCl, 1 MgCl2, 11 glucose, and 10 HEPES (pH 7.3, adjusted with NaOH). The strips were incubated overnight (12-24 h) at 4°C in Ca2+-free Krebs-HEPES solution containing papain (0.2-0.3 mg/ml) and 0.5 mM dithiothreitol. Thereafter, the strips were resuspended and incubated in Ca2+-free Krebs-HEPES solution containing collagenase (0.25-0.5 mg/ml) at 35°C for 10 min. The digested strips were cut into pieces with fine scissors and triturated with a blunt-tipped pipette until a sufficient number of single cells were released. The freshly dispersed cells were used for electrophysiological experiments. For measurement of [Ca2+]i, dispersed VSMCs were seeded on 60-mm tissue culture dishes (Falcon) and cultured in Dulbecco's modified Eagle's medium (DMEM) containing 10% FCS supplemented with 100 U/ml penicillin G and 100 µg/ml streptomycin at 37°C in a humidified 5% CO2-95% air atmosphere.
Electrophysiology and measurement of [Ca2+]i. Whole cell recordings and measurement of [Ca2+]i were performed as previously described (5, 11).
MTT assay and [3H]thymidine incorporation. Cells were seeded into 96-well plates at 5 × 103 cells/well for the assay with 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) and into 24-well plates at 4 × 104 cells/well for [3H]thymidine incorporation. They were incubated overnight in DMEM supplemented with 10% FCS at 37°C. The cells were deprived of serum for 24 h, washed with phosphate-buffered saline, and incubated with ET-1 for a further 48 h in serum-free DMEM with or without Ca2+ channel blockers. MTT assay and [3H]thymidine incorporation were performed as described previously (17).
Statistical analysis. Results are expressed as means ± SE. Data were subjected to a two-way analysis of variance. When a significant F-value was encountered, the Newman-Keuls multiple-range test was used to test for significant differences between treatment groups. A probability level of P < 0.05 was considered statistically significant.
Drugs. Boehringer Ingelheim (Ingelheim, Germany) kindly provided LOE-908. Other reagents were commercially obtained from the following sources: ET-1 from Peptide Institute (Osaka, Japan), SK&F-96365 from Biomol (Plymouth Meeting, PA), fluo 3-AM from Dojindo Laboratories (Kumamoto, Japan), nifedipine and MTT from Sigma (St. Louis, MO), and [3H]thymidine from NEN (Boston, MA).
| |
RESULTS |
|---|
|
TOP
ABSTRACT
INTRODUCTION
MATERIALS AND METHODS
RESULTS
DISCUSSION
REFERENCES
|
|---|
Effects of ET-1 on VOCC activation.
We first attempted to determine the maximal concentration of nifedipine
for complete inhibition of the L-type VOCC. We tested the effects of
various concentrations of nifedipine on an increase in
[Ca2+]i induced by high-K+ (50 mM) stimulation, which causes depolarization of the plasma membrane and
subsequent activation of the VOCC. Nifedipine completely inhibited the
high K+-induced increase in
[Ca2+]i at concentrations 
1 µM (data not
shown). Thus, in the following experiments, we added 1 µM nifedipine
to the bath solution to block the VOCC completely.
1 µM (Fig. 1B). In
contrast, the 0.1 nM ET-1-induced sustained increase in [Ca2+]i was not affected by nifedipine up to
1 µM (Fig. 1D).
|
Characterization of currents induced by ET-1 in ICA VSMCs with
whole cell recordings by patch clamp.
In the presence of 1 µM nifedipine, 10 nM ET-1 induced inward
currents in ICA VSMCs held at 
60 mV (Fig.
2A). Currents induced by ET-1
showed linear current-voltage relationships with reversal potentials of
5.4 ± 1.2 mV (n = 10; Fig. 2B).
Current-voltage relationships induced by ET-1 were not affected by the
reduction of the Cl
concentration in the bath solution
from 149 mM to 9 mM (data not shown). The reversal potential was
3.6 ± 1.4 mV (n = 10). To test whether channels
activated by ET-1 were permeable to Ca2+, all monovalent
cations in the bath solution were replaced with nonpermeant cation
N-methyl-D-glucamine (NMDG) while the
concentration of Ca2+ was elevated from 1 mM to 30 mM. Even
under such conditions, ET-1 induced inward currents in ICA VSMCs held
at 60 mV (Fig. 2C). The reversal potential was 10.3 ± 1.6 mV (n = 10; Fig. 2D).
|
Pharmacological properties of whole cell currents induced by ET-1
in ICA VSMCs.
To determine the maximally effective concentration of Ca2+
channel blockers such as SK&F-96365 or LOE-908, we first examined the
effects of various concentrations (~30 nM-30 µM) of these blockers on whole cell currents in ICA VSMCs induced by ET-1. SK&F-96365 and LOE-908 inhibited ET-1-induced currents in a
concentration-dependent manner with IC50 values of 2.1 ± 0.3 and 1.9 ± 0.3 µM, respectively, and maximal inhibition
was observed at concentrations 10 µM (data not shown). On the basis
of these data, we used 10 µM as the maximally effective concentration
of SK&F-96365 and LOE-908 in the following experiments.
2 to 5 mV (Fig. 3, B and
D). ET-1 failed to induce currents in ICA VSMCs pretreated
with 10 µM LOE-908, whereas ET-1 induced currents in ICA VSMCs
preincubated with 10 µM SK&F-96365 (data not shown). The magnitude of
the current in SK&F-96365-treated ICA VSMCs was ~35% of that in
nontreated ICA VSMCs.
|
Pharmacological properties of SOCC in ICA VSMCs. Generally, treatment of cells with thapsigargin (an inhibitor of Ca2+-pump ATPase on the membrane of sarcoplasmic/endoplasmic reticulum membrane) depletes the intracellular Ca2+ store and thereby activates the Ca2+ channel on the plasma membrane called the SOCC or capacitative Ca2+ entry channel, causing a sustained increase in [Ca2+]i (19). Therefore, the sustained increase in [Ca2+]i is regarded as an index of SOCC activity. A recent study showed that the thapsigargin-induced increase in [Ca2+]i in A7r5 cells was abolished by SK&F-96365, whereas it was unaffected by nifedipine and LOE-908 (11). Thus we characterized the pharmacological properties of SOCC in ICA VSMCs by using thapsigargin.
The sustained increase in [Ca2+]i in ICA VSMCs induced by 0.1 µM thapsigargin was suppressed by SK&F-96365 in a concentration-dependent manner, with an IC50 value of 2.7 ± 0.4 µM, and abolished at concentrations10 µM (Fig.
4A). However, the increase in
[Ca2+]i was not affected by LOE-908 up to a
concentration of 30 µM (Fig. 4B).
|
Pharmacological analysis of ET-1-induced increase in
[Ca2+]i.
The sustained increase in [Ca2+]i evoked by
10 nM ET-1 was suppressed by LOE-908 in a concentration-dependent
manner, and maximal inhibition was observed at concentrations 10 µM
(Fig. 5A). The extent of
maximal inhibition was ~60%. On the other hand, the sustained
increase in [Ca2+]i was suppressed by
SK&F-96365 in a concentration-dependent manner, and maximal inhibition
was observed at concentrations 10 µM (Fig. 5B). The
extent of maximal inhibition was ~80%. The sustained increase in
[Ca2+]i caused by 0.1 nM ET-1 was abolished
by 10 µM LOE-908 (Fig. 5C), whereas it was not affected by
10 µM SK&F-96365 (Fig. 5D).
|
10 nM
(Fig. 6B). In ICA VSMCs treated with LOE-908 before
stimulation with ET-1, the EC50 values were within 0.1 nM
and the maximal effect was observed at concentrations 0.1 nM (Fig.
6B). In ICA VSMCs treated with SK&F-96365 before stimulation
with ET-1, the EC50 values were 2.7 ± 0.3 nM and the
maximal effect was observed at concentrations 10 nM (Fig.
6B).
|
10 µM (Fig.
6C). The extent of maximal inhibition of the sustained
increase in [Ca2+]i in ICA VSMCs treated with
10 µM LOE-908 or 10 µM SK&F-96365 before stimulation with ET-1 was
similar to that in ICA VSMCs treated with 10 µM LOE-908 or 10 µM
SK&F-96365 after stimulation with ET-1 (~60% for LOE-908 and ~80%
for SK&F-96365; Fig. 6D). Moreover, the sustained increase
in [Ca2+]i was abolished by combined
treatment with 10 µM SK&F-96365 and 10 µM LOE-908 (Fig.
6D).
Effects of SK&F-96365 or LOE-908 on 10 nM ET-1-induced mitogenesis. After stimulation with 10 nM ET-1, both the number of viable cells as estimated by the MTT assay and mitogenic activity as estimated by [3H]thymidine incorporation increased with time up to 48 h (data not shown). Therefore, in subsequent experiments the stimulation time was set at 48 h.
ET-1 stimulated mitogenesis in ICA VSMCs in a concentration-dependent manner, with EC50 values of 0.7 ± 0.2 and 0.8 ± 0.1 nM for the MTT assay and [3H]thymidine incorporation, respectively. Maximal effects, ~5-fold increase in the MTT assay and ~4.2-fold increase for [3H]thymidine incorporation, were obtained at concentrations10 nM (Fig.
7).
|
10 µM (Fig.
8). The extent of maximal inhibition was
~80% (Fig. 9). Similarly, the
IC50 values of LOE-908 for inhibition of 10 nM ET-1-induced
mitogenesis were 3.2 ± 0.3 and 3.0 ± 0.2 µM for the MTT
assay and [3H]thymidine incorporation, respectively, with
maximal inhibition being observed at concentrations 10 µM (Fig. 8).
The extent of maximal inhibition was ~60% (Fig. 9). In contrast,
neither SK&F-96365 nor LOE-908 had any effect at concentrations up to
30 µM on the number of cells in the absence of ET-1 (Fig. 8).
Notably, 10 nM ET-1-induced mitogenesis was abolished by combined
treatment with maximally effective concentrations (10 µM) of LOE-908
and SK&F-96365 (Fig. 9).
|
|
| |
DISCUSSION |
|---|
|
TOP
ABSTRACT
INTRODUCTION
MATERIALS AND METHODS
RESULTS
DISCUSSION
REFERENCES
|
|---|
Characterization of Ca2+ channels activated by ET-1 in ICA VSMCs. On the basis of the sensitivity of the ET-1-induced sustained increase in [Ca2+]i to nifedipine, involvement of the VOCC in this response is estimated to be minor, within 10% (Fig. 1). This is in agreement with previous reports that Ca2+ influx through VOCCs has a minor role in ET-1-induced sustained increase in [Ca2+]i (16, 21). Moreover, a recent report demonstrated that the ETAR is negatively coupled to the L-type VOCC and is positively coupled to receptor-operated Ca2+-permeable channels in rabbit cerebral cortex arterioles (7). Therefore, Ca2+ channels other than the VOCC may play important roles in ET-1-induced sustained increase in [Ca2+]i in ICA VSMCs.
The whole cell currents induced by ET-1 are considered to be conducted through NSCCs for the following reasons. 1) Current-voltage relationships were linear, and the reversal potentials were close to 0 mV (Fig. 2B), indicating that the currents are conducted through either NSCCs or Cl channels. 2)
Reversal potentials of the ET-1-induced currents were unaffected by
changes in Cl concentration in the bath solution (see
RESULTS), indicating that the current is carried through
NSCCs. Furthermore, these NSCCs are permeable to Ca2+,
because currents can be induced in a bath solution containing only
Ca2+ as a movable cation (Fig. 2, C and
D). These data are in agreement with the previous report
that ET-1 can activate nifedipine-insensitive noncation channels in
VSMCs (2). The patch-clamp study showed that two
types of Ca2+-permeable NSCCs are activated by ET-1 in ICA
VSMCs: one type was sensitive to LOE-908 and resistant to SK&F-96365,
whereas the other was sensitive to both drugs (Fig. 3). From a
pharmacological viewpoint, these channels correspond to NSCC-1 and
NSCC-2, respectively, as defined in A7r5 cells (11).
ICA VSMCs are considered to possess SOCCs, because an increase in
[Ca2+]i as an index of Ca2+
influx through SOCCs could be induced by thapsigargin (Fig. 4). As
reported previously (11), Ca2+ current through
SOCCs cannot be monitored under our conditions of whole cell
recordings. This is probably because of latent activation of SOCCs
under basal conditions, which results from the presence of the
Ca2+ chelator EGTA in the pipette solution (to prevent
Ca2+-activated currents). EGTA is reported to deplete the
intracellular Ca2+ store and to activate SOCCs
(9). The SOCC thus defined in ICA VSMCs is sensitive to
SK&F-96365 and resistant to LOE-908, indicating that the
pharmacological properties of SOCCs in ICA VSMCs are the same as those
in A7r5 cells (11).
Given that the pharmacological properties of these Ca2+
channels have been clarified, we analyzed the involvement of
Ca2+ channels in ET-1-induced increase in
[Ca2+]i in the presence of nifedipine. The
ET-1-induced sustained increase in [Ca2+]i
consisted of three components in terms of sensitivity to SK&F-96365 and
LOE-908 in ICA VSMCs (Figs. 5 and 6; Table
1). NSCC-1 contributed ~20% to the
increase in [Ca2+]i and was resistant to
SK&F-96365 and sensitive to LOE-908. SOCC contributed ~40% to the
increase in [Ca2+]i and was resistant to
LOE-908 and sensitive to SK&F-96365 (Table 1). Because the LOE
908-sensitive part (contributing ~60%) of the increase in
[Ca2+]i consisted of Ca2+ influx
through NSCC-1 and NSCC-2, the contribution of Ca2+ influx
through NSCC-2 was calculated to be 40%. In conclusion, Ca2+ influx through NSCC-1, NSCC-2, and SOCC contributes
~20%, 40%, and 40%, respectively, to the increase in
[Ca2+]i induced by ET-1 in ICA VSMCs (Table
1). Moreover, the VICCs activated by ET-1 in ICA VSMCs may be
pharmacologically similar to those in A7r5 cells (11). In
ICA VSMCs, NSCC-1 is activated by 0.1 nM ET-1, whereas NSCC-2 and SOCC
are activated by ET-1 at concentrations 1 nM (Figs. 5 and 6).
Therefore, the sensitivity of NSCC-1 to ET-1 is higher than that of
NSCC-2 or SOCC to ET-1. These results indicate that the sensitivity
pattern of VICCs to ET-1 in ICA VSMCs may be similar to that in A7r5
cells (11).
|
Characterization of Ca2+ channels involved in ET-1-induced mitogenesis in ICA VSMCs. ET-1 induces mitogenic response in ICA VSMCs, judging from results of MTT assay and [3H]thymidine incorporation (Fig. 7). As demonstrated by sensitivity to BQ-123 and BQ-788, ET-1 mediates increases in mitogenesis through ETARs (data not shown).
In light of the nifedipine sensitivity of ET-1-induced mitogenesis, Ca2+ channels other than VOCCs may play important roles in ET-1-induced mitogenesis in ICA VSMCs. Three types of VICCs seem to be involved in ET-1-induced mitogenesis in terms of its sensitivity to LOE-908 and SK&F-96365 (Figs. 8 and 9). One type of Ca2+ channel is sensitive to LOE-908 and resistant to SK&F-96365, another type is sensitive to both LOE-908 and SK&F-96365, and the third type is resistant to LOE-908 and sensitive to SK&F-96365. On the basis of pharmacological criteria, these channels are considered to be NSCC-1, NSCC-2, and SOCC, respectively. Moreover, the percent contribution of NSCC-1, NSCC-2, and SOCC to ET-1-induced mitogenesis is calculated to be ~20%, 40%, and 40%, respectively (Table 1). The inhibitory action of SK&F-96365 or LOE-908 on ET-1-induced mitogenesis may be mediated by blockade of Ca2+ entry through VICCs for the following reasons. 1) From the results of patch clamp and [Ca2+]i monitoring, ET-1 was found to activate three types of VICCs in ICA VSMCs, namely, NSCC-1, NSCC-2, and SOCC (Table 1). 2) The IC50 values of SK&F-96365 and LOE-908 for ET-1-induced mitogenesis and the extent of inhibition of the response by these blockers (Fig. 8; Table 1) correlated well with those for the ET-1-induced [Ca2+]i response (Fig. 3). 3) Neither SK&F-96365 nor LOE-908 is considered to exert cytotoxic effects on quiescent cells, judging from data from MTT and [3H]thymidine incorporation assays (Fig. 8). In conclusion, ET-1 activates VICCs such as NSCC-1, NSCC-2, and SOCC in ICA VSMCs. Notably, Ca2+ influx through these channels plays an essential role in ET-1-induced mitogenesis in ICA VSMCs. We recently showed (17) that the ET-1-induced mitogenic response in Chinese hamster ovary cells expressing recombinant ETARs involves a mitogen-activated protein kinase cascade, the activation of which is dependent on both protein kinase C and phosphatidylinositol 3-kinase. However, it is not known whether the same signaling pathways operate in ICA VSMCs. It remains to be determined which signaling pathways are involved in the ET-1-induced mitogenic response and which step(s) of the intracellular signaling pathways requires Ca2+.| |
ACKNOWLEDGEMENTS |
|---|
We thank Boehringer Ingelheim (Ingelheim, Germany) for the kind gift of LOE-908.
| |
FOOTNOTES |
|---|
Address for reprint requests and other correspondence: Y. Kawanabe, Dept. of Neurosurgery, Kyoto Univ. Faculty of Medicine, 54 Shougoin-Kawaharachou, Sakyo-ku, Kyoto 606-8507, Japan (E-mail: kawanabe{at}kuhp.kyoto-u.ac.jp).
The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
10.1152/ajpcell.00227.2001
Received 3 August 2001; accepted in final form 1 October 2001.
| |
REFERENCES |
|---|
|
TOP
ABSTRACT
INTRODUCTION
MATERIALS AND METHODS
RESULTS
DISCUSSION
REFERENCES
|
|---|
1.
Burke, SE,
Lubbers NL,
Gagne GD,
Wessale JL,
Dayton BD,
Wegner CD,
and
Opgenorth TJ.
Selective antagonism of the ET(A) receptor reduces neointimal hyperplasia after balloon-induced vascular injury in pigs.
J Cardiovasc Pharmacol
30:
33-41,
1997[Web of Science][Medline].
2.
Chen, C,
and
Wagoner PK.
Endothelin induces a nonselective cation current in vascular smooth muscle cells.
Circ Res
69:
447-454,
1991
3.
Douglas, SA,
Louden C,
Vickery-Clark LM,
Storer BL,
Hart T,
Feuerstein GZ,
Elliott JD,
and
Ohlstein EH.
A role for endogenous endothelin-1 in neointimal formation after rat carotid artery balloon angioplasty. Protective effects of the novel nonpeptide endothelin receptor antagonist SB 209670.
Circ Res
75:
190-197,
1994
4.
Encabo, A,
Romanin C,
Birke FW,
Kukovetz WR,
and
Groschner K.
Inhibition of a store-operated Ca2+ entry pathway in human endothelial cells by the isoquinoline derivative LOE 908.
Br J Pharmacol
119:
702-706,
1996[Web of Science][Medline].
5.
Enoki, T,
Miwa S,
Sakamoto A,
Minowa T,
Komuro T,
Kobayashi S,
Ninomiya H,
and
Masaki T.
Long-lasting activation of cation current by low concentration of endothelin-1 in mouse fibroblast and smooth muscle cells of rabbit aorta.
Br J Pharmacol
115:
479-485,
1995[Web of Science][Medline].
6.
Gardner, P.
Calcium and T lymphocyte activation.
Cell
59:
15-20,
1989[Web of Science][Medline].
7.
Guibert, C,
and
Beech DJ.
Positive and negative coupling of the endothelin ETA receptor to Ca2+-permeable channels in rabbit cerebral cortex arterioles.
J Physiol (Lond)
514:
843-856,
1999
8.
Haak, T,
Marz W,
Jungmann E,
Hausser S,
Siekmeier R,
Gross W,
and
Usadel KH.
Elevated endothelin levels in patients with hyperlipoproteinemia.
Clin Investig
72:
580-584,
1994[Web of Science][Medline].
9.
Hoth, M,
and
Penner R.
Depletion of intracellular calcium stores activates a calcium current in mast cells.
Nature
355:
353-358,
1992[Medline].
10.
Inoue, R,
and
Kuriyama H.
Dural regulation of cation-selective channels by muscarinic and 
1-adrenergic receptors in the rabbit portal vein.
J Physiol (Lond)
465:
427-448,
1993
11.
Iwamuro, Y,
Miwa S,
Zhang XF,
Minowa T,
Enoki T,
Okamoto Y,
Hasegawa H,
Furutani H,
Okazawa M,
Ishikawa M,
Hashimoto N,
and
Masaki T.
Activation of three types of voltage-independent Ca2+ channel in A7r5 cells by endothelin-1 as revealed by a novel Ca2+ channel blocker LOE 908.
Br J Pharmacol
126:
1107-1114,
1999[Web of Science][Medline].
12.
Jung, F,
Selvaraj S,
and
Gargus JJ.
Blockers of platelet-derived growth factor-activated nonselective cation channel inhibit cell proliferation.
Am J Physiol Cell Physiol
262:
C1464-C1470,
1992
13.
Lerman, A,
Edwards BS,
Hallett JW,
Heublein DM,
Soderg SM,
and
Burnett JC.
Circulating and tissue endothelin immunoreactivity in advanced atherosclerosis.
N Engl J Med
325:
997-1001,
1991[Abstract].
14.
Meritt, JE,
Airmstrong WP,
Benham CD,
Hallam TJ,
Jacob R,
Jaxa-Chamiec A,
Leigh BK,
McCarthy SA,
Moores KE,
and
Rink TJ.
SK&F 96365, a novel inhibitor of receptor-mediated calcium entry.
Biochem J
271:
515-522,
1990[Web of Science][Medline].
15.
Minowa, T,
Miwa S,
Kobayashi S,
Enoki T,
Zhang XF,
Komuro T,
Iwamuro Y,
and
Masaki T.
Inhibitory effect of nitrovasodilators and cyclic GMP on ET-1-activated Ca2+-permeable nonselective cation channel in rat aortic smooth muscle cells.
Br J Pharmacol
120:
1536-1544,
1997[Web of Science][Medline].
16.
Miwa, S,
Iwamuro Y,
Zhang XF,
Inoki T,
Okamoto Y,
Okazawa M,
and
Masaki T.
Ca2+ entry channels in rat thoracic aortic smooth muscle cells activated by endothelin-1.
Jpn J Pharmacol
80:
281-288,
1999[Medline].
17.
Sugawara, F,
Ninomiya H,
Okamoto Y,
Miwa S,
Mazda O,
Katsura Y,
and
Masaki T.
Endothelin-1-induced mitogenic responses of Chinese hamster ovary cells expressing human endothelin A: the role of a wortmannin-sensitive signaling pathway.
Mol Pharmacol
49:
447-445,
1996[Abstract].
18.
Takuwa, N,
Zhou W,
Kumada M,
and
Takuwa Y.
Ca2+-dependent stimulation of retinoblastoma gene product phosphorylation and p34cdc2 kinase activation in serum-stimulated human fibroblasts.
J Biol Chem
268:
138-145,
1993
19.
Thasreup, O,
Cullen PJ,
Drobak BK,
Hanley MR,
and
Dawson AP.
Thapsigargin, a tumor promoter, discharges intracellular Ca2+ stores by specific inhibition of the endoplasmic reticulum Ca2+-ATPase.
Proc Natl Acad Sci USA
87:
2466-2470,
1990
20.
Yanagisawa, M,
Kurihara H,
Kimura S,
Tomobe Y,
Kobayashi M,
Mitsui Y,
Goto K,
and
Masaki T.
A novel potent vasoconstrictor peptide produced by vascular endothelial cells.
Nature
332:
411-415,
1988[Medline].
21.
Zhang, XF,
Iwamuro Y,
Enoki T,
Okazawa M,
Lee K,
Komuro T,
Minowa T,
Okamoto Y,
Hasegawa H,
Furutani H,
Miwa S,
and
Masaki T.
Pharmacological characterization of Ca2+ entry channels in endothelin-1-induced contraction of rat aorta using LOE 908 and SK&F 96365.
Br J Pharmacol
127:
1388-1398,
1999[Web of Science][Medline].
This article has been cited by other articles:
|
|
 |
|
  S. Chen, Y. Qiong, and D. G. Gardner A Role for p38 Mitogen-Activated Protein Kinase and c-Myc in Endothelin-Dependent Rat Aortic Smooth Muscle Cell Proliferation Hypertension, February 1, 2006; 47(2): 252 - 258. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 Y. Kawanabe, N. Hashimoto, and T. Masaki Characterization of G proteins involved in activation of nonselective cation channels and arachidonic acid release by norepinephrine/{alpha}1A-adrenergic receptors Am J Physiol Cell Physiol, March 1, 2004; 286(3): C596 - C600. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 Y. Kawanabe, N. Hashimoto, and T. Masaki Involvements of Voltage-Independent Ca2+ Channels and Phosphoinositide 3-Kinase in Endothelin-1-Induced PYK2 Tyrosine Phosphorylation Mol. Pharmacol., April 1, 2003; 63(4): 808 - 813. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Y. Kawanabe, N. Hashimoto, and T. Masaki Role of phosphoinositide 3-kinase in the nonselective cation channel activation by endothelin-1/endothelinB receptor Am J Physiol Cell Physiol, February 1, 2003; 284(2): C506 - C510. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 Y. Kawanabe, N. Hashimoto, and T. Masaki Characterization of Ca2+ channels involved in ET-1-induced transactivation of EGF receptors Am J Physiol Heart Circ Physiol, December 1, 2002; 283(6): H2671 - H2675. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Y. Kawanabe, N. Hashimoto, and T. Masaki Effects of Phosphoinositide 3-Kinase on the Endothelin-1-Induced Activation of Voltage-Independent Ca2+ Channels and Mitogenesis in Chinese Hamster Ovary Cells Stably Expressing EndothelinA Receptor Mol. Pharmacol., September 1, 2002; 62(3): 756 - 761. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Y. Kawanabe, Y. Okamoto, S. Miwa, N. Hashimoto, and T. Masaki Molecular Mechanisms for the Activation of Voltage-Independent Ca2+ Channels by Endothelin-1 in Chinese Hamster Ovary Cells Stably Expressing Human EndothelinA Receptors Mol. Pharmacol., July 1, 2002; 62(1): 75 - 80. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |
) and ICA VSMCs pretreated with 10 µM LOE-908
(
) or 10 µM SK&F-96365 (
) for 10 min.
Monitoring of [Ca2+]i was performed as
described in MATERIALS AND METHODS. C:
inhibitory effects of pretreatment for 10 min with various
concentrations of LOE-908 (
