title: Differential effects of strychnine on two types of vascular muscle.
abstract: Strychnine (10(-5)-3 x 10(-4) M) increased the amplitude and duration of the spontaneous electrical and mechanical activity of the rat isolated portal vein. Similar effects were seen with tetraethylammonium and 4-aminopyridine. This stimulant action of strychnine was unaffected by tetrodotoxin (3 x 10(-7) M) or prazosin (5 x 10(-8) M) but was significantly reduced by verapamil (3 x 10(-8) M). On the isolated aorta, only inhibitory actions of strychnine were observed, yet tetraethylammonium and 4-aminopyridine had excitatory actions. It is suggested that the stimulant actions of strychnine on the portal vein are likely to be due to a reduction in potassium conductance and/or an increase in calcium conductance of the smooth muscle cell membrane.
mesh_terms: D015761:4-Aminopyridine; D000631:Aminopyridines / Q000494:pharmacology; D000818:Animals; D001013:Aorta, Thoracic; D002317:Cardiovascular Agents / Q000494:pharmacology; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009131:Muscle, Smooth, Vascular / Q000502:physiology*; D011169:Portal Vein; D011224:Prazosin / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013331:Strychnine / Q000494:pharmacology*; D019789:Tetraethylammonium; D013757:Tetraethylammonium Compounds / Q000494:pharmacology; D013779:Tetrodotoxin / Q000494:pharmacology; D014700:Verapamil / Q000494:pharmacology
chemical_list: D000631:Aminopyridines; D002317:Cardiovascular Agents; D013757:Tetraethylammonium Compounds; D013779:Tetrodotoxin; D019789:Tetraethylammonium; D015761:4-Aminopyridine; D014700:Verapamil; D013331:Strychnine; D011224:Prazosin