Voltage-activated Ca2+ currents in insulin-secreting cells.
Membrane voltage and voltage-clamped membrane currents have been investigated with the whole-cell patch clamp method in the insulin-secreting cell line RINm5F. The mean resting membrane potential of RINm5F cells was found to be -52 mV. Overshooting spike potentials could be evoked by depolarising voltage steps in the absence of a secretagogue. Inward membrane currents evoked by depolarising voltage steps were dependent upon extracellular Ca2+ and blocked by Co2+, nifedipine and verapamil. Outward membrane currents which were evoked by depolarising voltage steps to positive membrane potentials were reduced when Ca2+ entry was prevented. It is concluded that the voltage-activated Ca2+ currents underlie the voltage-activated spike potentials recorded from insulin-secreting cells.
Findlay
I
I
Dunne
M J
MJ
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D003035:Cobalt / Q000494:pharmacology; D004533:Egtazic Acid / Q000494:pharmacology; D004553:Electric Conductivity; D005071:Evoked Potentials; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007473:Ion Channels / Q000378:metabolism*; D008564:Membrane Potentials; D009543:Nifedipine / Q000494:pharmacology; D014700:Verapamil / Q000494:pharmacology
D007328:Insulin; D007473:Ion Channels; D003035:Cobalt; D004533:Egtazic Acid; D014700:Verapamil; D009543:Nifedipine; D002118:Calcium