Triiodothyronine affects the electrical properties of GH3 cells.
Electrophysiological experiments show that T3 has a direct effect on the cell membrane of GH3 cells, a transformed line from the rat pituitary. Slope conductance versus membrane potential, resting membrane resistance, potential, capacity and action potentials were measured in this study. Using a current clamp technique, the effects of tetrodotoxin, tetraethylammonium, apamin, and nifedipine were measured and compared with those directly evoked by T3. T3 increased the slope conductance: 1. at around -60 mV, as did tetrodotoxin (Na+ channel blocker); 2. at about -40 mV, as did nifedipine (Ca2+ channel blocker), but decreased this conductance strongly between -20 and -30 mV, as did both nifedipine and apamin (Ca2(+)-sensitive K+ channel blocker). Action potentials were inhibited by T3 and by nifedipine. Action potentials in these cells are primarily related to Ca2+ ions. It seems that T3 inhibits the Ca2+ current and, as a consequence, the Ca2(+)-sensitive K+ current.
du Pont
J S
JS
Department of Experimental Zoology, University of Amsterdam, The Netherlands.
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D001030:Apamin / Q000494:pharmacology; D002461:Cell Line, Transformed; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology; D004553:Electric Conductivity; D004594:Electrophysiology; D008564:Membrane Potentials / Q000187:drug effects; D009543:Nifedipine / Q000494:pharmacology; D010902:Pituitary Gland / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D019789:Tetraethylammonium; D013757:Tetraethylammonium Compounds / Q000494:pharmacology; D013779:Tetrodotoxin / Q000494:pharmacology; D014284:Triiodothyronine / Q000494:pharmacology*
D013757:Tetraethylammonium Compounds; D014284:Triiodothyronine; D001030:Apamin; D013779:Tetrodotoxin; D019789:Tetraethylammonium; D009543:Nifedipine