Plasma membrane Ca2+ transport: Antagonism by several potential inhibitors

Abstract

Inside-out vesicles prepared from human red blood cells took up Ca2+ by an active transport process. Membranes from the same red blood cells displayed Ca2+-activated, Mg2+-dependent adenosine triphosphatase activity. Both the initial rate of Ca2+ transport and the (Ca2++Mg2+)-adenosine triphosphatase activity were increased approximately twofold by the calcium binding protein, calmodulin. Activities in the absence of added calmodulin were termed basal activities. Calmodulin-activated Ca2+ transport and adenosine triphosphatase activities could be antagonized in a relatively selective fashion by the phenothiazine tranquilizer drug, trifluoperazine. High concentrations of trifluoperazine also inhibited basal Ca2+ transport and adenosine triphosphatase activity. By contrast, calmodulin binding protein from beef brain selectively antagonized the effect of calmodulin on Ca2+ transport with no inhibition of basal activity. Ruthenium red antagonized calmodulin-activated and basal activity with equal potency. The results demonstrate that although phenothiazines can act as relatively selective antagonists of calmodulin-induced effects, other effects are possible and cannot be ignored. Calmodulin-binding protein may be a useful tool in the analysis of calmodulin functions. Ruthenium red probably interacts with Ca2+ pump adenosine triphosphatase at a site not related to calmodulin.

DOI: 10.1007/BF01871034

5 Figures and Tables

Statistics

0200400'85'88'91'94'97'00'03'06'09'12'15
Citations per Year

324 Citations

Semantic Scholar estimates that this publication has 324 citations based on the available data.

See our FAQ for additional information.

Cite this paper

@article{Hinds1981PlasmaMC, title={Plasma membrane Ca2+ transport: Antagonism by several potential inhibitors}, author={Thomas R. Hinds and Beat U. Raess and Frank F Vincenzi}, journal={The Journal of Membrane Biology}, year={1981}, volume={58}, pages={57-65} }