Li+ inhibition of membrane current responses to epinephrine in guinea-pig ventricular cells.
Membrane currents of guinea-pig ventricular myocytes were recorded using the whole-cell voltage clamp method. The epinephrine-induced increase in Ca2+ current (2.9 +/- 0.5 times control) was reduced (1.8 +/- 0.3 times) by replacing Na+ with Li+ in the bathing solution. In addition, 0.5 microM epinephrine increased a time-independent membrane conductance in the Na+ external solution, having a reversal potential of -19 +/- 3 mV (epinephrine-induced current). In the Li+ external solution, however, 0.5 microM epinephrine failed to induce the epinephrine-induced current. The findings are consistent with the reported Li+ inhibition of GTP-binding protein and/or adenylate cyclase.
Matsuoka
S
S
Department of Physiology, Faculty of Medicine, Kyushu University, Fukuoka, Japan.
Noma
A
A
Powell
T
T
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D000242:Cyclic AMP / Q000502:physiology; D004553:Electric Conductivity; D004837:Epinephrine / Q000494:pharmacology*; D006168:Guinea Pigs; D007545:Isoproterenol / Q000494:pharmacology; D008094:Lithium / Q000494:pharmacology*; D008564:Membrane Potentials / Q000187:drug effects; D009206:Myocardium / Q000166:cytology / Q000378:metabolism*; D013997:Time Factors
D008094:Lithium; D000242:Cyclic AMP; D007545:Isoproterenol; D002118:Calcium; D004837:Epinephrine