Am J Physiol Cell Physiol AJP: Regulatory, Integrative and Comparative Physiology
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Am J Physiol Cell Physiol 265: C1281-C1288, 1993;
0363-6143/93 $5.00
This Article
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Kleineke, J. W.
Right arrow Articles by Janssens, P. A.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Kleineke, J. W.
Right arrow Articles by Janssens, P. A.

AJP - Cell Physiology, Vol 265, Issue 5 C1281-C1288, Copyright © 1993 by American Physiological Society

ARTICLES

Hormone-induced rise in cytosolic Ca2+ in axolotl hepatocytes: extracellular origin and control by cAMP

J. W. Kleineke and P. A. Janssens
Division of Biochemistry and Molecular Biology, School of Life Sciences, Australian National University, Canberra.

In amphibian liver, signal transduction of [Arg8]vasotocin (AVT), a "classical" Ca(2+)-dependent hormone in rat liver, is mediated via the generation of adenosine 3',5'-cyclic monophosphate (cAMP) and not via inositol 1,4,5-trisphosphate [Ins(1,4,5)P3]. In isolated hepatocytes from axolotl, hormones that stimulated cAMP formation (the order of efficacy was glucagon > isoprenaline > epinephrine > or = AVT) also provoked a pronounced increase in cytosolic Ca2+, as indicated from changes in fura 2 fluorescence. 8-Bromoadenosine 3',5'-cyclic monophosphate at 100 microM was as potent as maximally effective concentrations of glucagon. Ins(1,4,5)P3 mobilized Ca2+ from the endoplasmic reticulum of saponin-permeabilized axolotl hepatocytes with a half-maximal effect at 0.65 microM, as did GTP (20 microM), even in the absence of polyethylene glycol. However, the hormonally induced increase in cytosolic Ca2+ was not due to a mobilization of the cation from internal stores by Ins(1,4,5)P3, but to an increased inflow from the extracellular medium. We conclude that in axolotl liver, in contrast to rat liver, hormones stimulate the production of cAMP that, in addition to stimulating processes such as glycogenolysis, also regulates the opening of an ion gate in the plasma membrane, which allows the inflow of Ca2+. To our knowledge this is the first demonstration of a second messenger-operated Ca2+ channel in a splanchnic tissue.


This article has been cited by other articles:


Home page
 Am. J. Physiol. Cell Physiol.Home page
T. Lenz and J. W. Kleineke
Hormone-induced rise in cytosolic Ca2+ in axolotl hepatocytes: properties of the Ca2+ influx channel
Am J Physiol Cell Physiol, November 1, 1997; 273(5): C1526 - C1532.
[Abstract] [Full Text] [PDF]


HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Visit Other APS Journals Online