Am J Physiol Cell Physiol AJP: Heart and Circulatory Physiology
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Am J Physiol Cell Physiol 260: C17-C25, 1991;
0363-6143/91 $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 Imaizumi, Y.
Right arrow Articles by Watanabe, M.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Imaizumi, Y.
Right arrow Articles by Watanabe, M.

AJP - Cell Physiology, Vol 260, Issue 1 C17-C25, Copyright © 1991 by American Physiological Society

ARTICLES

Mechanisms of NE-induced reduction of Ca current in single smooth muscle cells from guinea pig vas deferens

Y. Imaizumi, M. Takeda, K. Muraki and M. Watanabe
Department of Chemical Pharmacology, Faculty of Pharmaceutical Sciences, Nagoya City University, Japan.

Effects of norepinephrine (NE) on voltage-dependent Ca channel current (ICa) were examined applying whole cell patch-clamp technique to single smooth muscle cells freshly isolated from vas deferens of the guinea pig. K currents and contraction of the cell were abolished by Cs and EGTA in the pipette solution, respectively. The peak ICa and Ba current (IBa) elicited by depolarization from -60 mV in a solution containing 2.2 mM Ca or Ba were reduced by 10-60% in voltage- and dose-dependent manners by the application of NE or phenylephrine. This effect was greatly attenuated in the presence of prazosin. The decrease in IBa was always smaller than that in ICa at any potential. Even after simultaneous application of 5 mM caffeine and 10 microM NE to the cells in a Ba-containing solution, the second challenge with NE again reduced IBa in a similar manner. The decrease in IBa by 10 microM NE could not be explained well by a small shift (-5 mV) of the voltage dependence of the steady-state inactivation. The effect of NE on IBa was irreversibly enhanced by 0.1 mM guanosine 5'-O-(3-thiotriphosphate) and almost abolished by 1 mM guanosine 5'-O-(2-thiodiphosphate) added to the pipette solution but appeared not to be affected by the treatment with pertussis toxin. It can be concluded that, under these experimental conditions, the activation of alpha 1-adrenoceptor in vas deferens smooth muscle cells reduces Ca channel activity possibly via a mechanism involving GTP-binding protein in addition to Ca-mediated Ca channel inactivation mechanism.


This article has been cited by other articles:


Home page
 Pharmacol. Rev.Home page
H. Karaki, H. Ozaki, M. Hori, M. Mitsui-Saito, K.-I. Amano, K.-I. Harada, S. Miyamoto, H. Nakazawa, K.-J. Won, and K. Sato
Calcium Movements, Distribution, and Functions in Smooth Muscle
Pharmacol. Rev., June 1, 1997; 49(2): 157 - 230.
[Abstract] [Full Text] [PDF]


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