Evidence that the spasmogenic action of tetraethylammonium in guinea-pig trachealis is both direct and dependent on the cellular influx of calcium ion.
1 Tetraethylammonium (TEA, 1-8 mmol/l) evoked spasm of guinea-pig trachealis which was unaffected by atropine (1 mumol/l), mepyramine (1 mumol/l) or tetrodotoxin (3 mumol/l). 2 The spasm evoked by TEA was markedly suppressed in Ca2+-free Krebs solution while that evoked by acetylcholine was much less affected. 3 Extracellular electrical recording showed that exposure to Ca2+-free Krebs solution suppressed both spontaneous electrical slow wave activity of the trachea and the spasm and slow waves induced by TEA. These effects were reversible. 4 TEA (2 and 8 mmol/l) increased the lanthanum-resistant calcium fraction of trachea. 5 It is concluded that TEA acts directly on the smooth muscle of guinea-pig trachea, that the spasm and electrical slow waves evoked are Ca2+-dependent and that the cellular influx of Ca2+ is increased.
D000818:Animals; D001285:Atropine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D004558:Electric Stimulation; D004594:Electrophysiology; D005260:Female; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007811:Lanthanum / Q000494:pharmacology; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects* / Q000378:metabolism; D011738:Pyrilamine / Q000494:pharmacology; D013035:Spasm / Q000139:chemically induced; D019789:Tetraethylammonium; D013757:Tetraethylammonium Compounds / Q000494:pharmacology*; D013779:Tetrodotoxin / Q000494:pharmacology; D014132:Trachea / Q000187:drug effects*
D013757:Tetraethylammonium Compounds; D013779:Tetrodotoxin; D019789:Tetraethylammonium; D007811:Lanthanum; D001285:Atropine; D011738:Pyrilamine; D002118:Calcium