Voltage-dependent Ca2+ channel and Na+ channel in frog taste cells.
Frog taste cells were hyperpolarized by injecting an inward current pulse, and regenerative anode-break potentials were observed at the termination of the current pulse. The results obtained are as follows. 1) The magnitude of the anode-break potentials increased with the extent of hyperpolarization of taste cells and reached a saturation level around -200 mV. 2) The magnitudes of the anode-break potentials observed in 80 different taste cells hyperpolarized to about -200 mV were distributed widely from cell to cell. The average magnitude was 39 mV. 3) The anode-break potentials were recorded after the lingual artery was perfused with artificial solutions containing various channel blockers. The results indicated that the anode-break potentials are composed of Na+ and Ca2+ components. 4) The slope of the current-voltage relation obtained with cells hyperpolarized to 100 mV was appreciably decreased above -50 mV by application of tetrodotoxin to the perfusing solution. Discussion was made on possible roles of the voltage-dependent Na+ and Ca2+ channels in the electrotonic spreading of the depolarization at the receptor membranes to the synaptic area and in releasing a chemical transmitter.
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D003035:Cobalt / Q000494:pharmacology; D004533:Egtazic Acid / Q000494:pharmacology; D004558:Electric Stimulation; D066298:In Vitro Techniques; D007473:Ion Channels / Q000502:physiology*; D008564:Membrane Potentials / Q000187:drug effects; D011892:Rana catesbeiana; D012964:Sodium / Q000378:metabolism*; D013650:Taste Buds / Q000502:physiology*; D013779:Tetrodotoxin / Q000494:pharmacology
D002121:Calcium Channel Blockers; D007473:Ion Channels; D003035:Cobalt; D013779:Tetrodotoxin; D004533:Egtazic Acid; D012964:Sodium; C018021:cobaltous chloride; D002118:Calcium