Skip to Main content Skip to Navigation
Journal articles

Are B-type Ca 2+ Channels of Cardiac Myocytes Akin to the Passive Ion Channel in the Plasma Membrane Ca 2+ Pump?

Abstract : The present study demonstrates that B-type Ca2+ channels observed in rat ventricular myocytes markedly reacted to agents known to affect the ion-motive plasma membrane Ca2+-ATPase (PMCA) pump. Chlorpromazine (CPZ)-activated B-type Ca2+ channels were completely blocked by internal application of PMCA pump inhibitors, namely La3+ (100 microm), eosin (10 microm) and AIF(3) (100 microm). Calmodulin (50 U/ml), the main endogenous positive regulator of PMCA, was unable to activate but significantly reduced CPZ-activated B-type channel activity. In the same manner, ATP (1 and 4 mm), the main energizing substrate of PMCA, was able to reversibly and significantly reduce this activity in a dose-dependent manner. Interestingly, anti-PMCA antibody 5F10, but not anti-Na/K ATPase antibody (used as a negative control) induced a marked Ba2+-conducting channel activity that shared the same characteristics with that of CPZ-activated B-type channels. 5F10-Activated channels were mostly selective towards Ba2+ , mainly had three observed conductance levels (23, 47 and 85 pS), were observed with a frequency of about 1 out of 5 membrane patches and were completely blocked by 10 microm eosin. These results suggest that B-type Ca2+ channels are some form of the PMCA pump.
Document type :
Journal articles
Complete list of metadata

https://hal.inrae.fr/hal-03119303
Contributor : Caroline Pinet <>
Submitted on : Saturday, January 23, 2021 - 5:24:01 PM
Last modification on : Sunday, January 24, 2021 - 3:18:06 AM

Links full text

Identifiers

Collections

Citation

S. Antoine, C. Pinet, A. Coulombe. Are B-type Ca 2+ Channels of Cardiac Myocytes Akin to the Passive Ion Channel in the Plasma Membrane Ca 2+ Pump?. Journal of Membrane Biology, Springer Verlag (Germany), 2001, 179 (1), pp.37-50. ⟨10.1007/s002320010035⟩. ⟨hal-03119303⟩

Share

Metrics

Record views

10