HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Poggioli, J. Articles by Claret, M. Search for Related Content PubMed PubMed Citation Articles by Poggioli, J. Articles by Claret, M. Social Bookmarking                      What's this?

J. Biol. Chem., Vol. 260, Issue 6, 3289-3294, 03, 1985

A regulatory calcium-binding site for calcium channel in isolated rat hepatocytes

J Poggioli, JP Mauger, F Guesdon and M Claret

Loading isolated rat hepatocytes with high concentrations of the fluorescent Ca2+-chelator quin-2 in the absence of extracellular Ca2+ decreases by about 3-fold the cytosolic Ca2+ concentration ([Ca2+]i). In these low [Ca2+]i cells, the initial 45Ca2+ uptake rate, assumed to represent the Ca2+ influx, is stimulated to a level close to that promoted by maximal doses of vasopressin and angiotensin II in control cells. The subsequent addition of Ca2+ to the quin-2-loaded hepatocytes results in a rapid increase in [Ca2+]i and a return of Ca2+ influx towards the basal level usually observed in nonloaded cells. This indicates that the Ca2+ influx is dependent on [Ca2+]i but not on the quin-2 load itself. In the low [Ca2+]i cells, both the apparent Km and the apparent Vmax of the Ca2+ influx are increased as compared to the controls, indicating that the properties of the channels activated by lowering [Ca2+]i are apparently identical to those initiated by the hormones (Mauger, J.-P., Poggioli, J., Guesdon, F., and Claret, M. (1984) Biochem. J. 221, 121-127). It is proposed that in the isolated rat hepatocytes there is an inverse relationship between the Ca2+ influx and [Ca2+]i. Under resting conditions, [Ca2+]i might be high enough to partially inhibit the Ca2+ influx via a Ca2+ binding to an inhibitory site presumably located at the inner membrane surface. The role of the site in the hormonal action is discussed.
CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				J. W. Putney Jr, L. M. Broad, F.-J. Braun, J.-P. Lievremont, and G. S. J. Bird Mechanisms of capacitative calcium entry J. Cell Sci., March 8, 2002; 114(12): 2223 - 2229. [Abstract] [Full Text] [PDF]

				S. Zhang, Y. Hirano, and M. Hiraoka Arginine Vasopressin–Induced Potentiation of Unitary L-Type Ca2+ Channel Current in Guinea Pig Ventricular Myocytes Circ. Res., April 1, 1995; 76(4): 592 - 599. [Abstract] [Full Text]