Effect of isoproterenol on the L-type Ca2+ current in cardiac cells from rats and hybernating ground squirrels.
The perforated patch clamp method was used to study the effect of the agonist of beta-adrenoreceptors isoproterenol on L-type Ca2+ current in cardiocytes of rats and ground squirrels in two states: active and hibernating. It is shown that isoproterenol exerts a dual effect on Ca2+ currents of rats and ground squirrels in the active state: at Vh = -50 mV, the current increases, whereas at Vh = -30 mV, it decreases. In hibernating ground squirrels, the dual effect of isoproterenol is not observed: isoproterenol increases Ca2+ current at any Vh values. The hypothesis is put forward that, during the entrance of ground squirrels into hibernation, the phosphorylation of one of the sites (not cAMP-dependent) of L-type Ca2+ channels is blocked.
Kokoz YuM
Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region.
Grichenko
A S
AS
Korystova
A F
AF
Lankina
D A
DA
Markevich
N I
NI
D000318:Adrenergic beta-Agonists / Q000378:metabolism* / Q000494:pharmacology; D000818:Animals; D015220:Calcium Channels / Q000502:physiology*; D020746:Calcium Channels, L-Type; D006321:Heart / Q000502:physiology*; D006605:Hibernation / Q000502:physiology*; D007545:Isoproterenol / Q000378:metabolism* / Q000494:pharmacology; D009206:Myocardium / Q000166:cytology / Q000378:metabolism; D010766:Phosphorylation; D051381:Rats; D017208:Rats, Wistar; D012589:Sciuridae
D000318:Adrenergic beta-Agonists; D015220:Calcium Channels; D020746:Calcium Channels, L-Type; D007545:Isoproterenol