Effect of 4-aminopyridine and 3,4-diaminopyridine on guinea-pig isolated ileum.
1. 4-Aminopyridine and 3,4-diaminopyridine produced concentration-dependent contraction on guinea-pig isolated ileum incubated in Tyrode solution. The EC30 values were 1.14 x 10(-4) and 1.39 x 10(-4) M, respectively. 2. Calcium channel blockers such as verapamil, diltiazem, nifedipine, flunarizine, and lanthanum chloride antagonized the contracting effect induced by 4-aminopyridine and 3,4-diaminopyridine in guinea-pig isolated ileum. 3. Diazoxide and atropine sulphate behaved similarly as antagonists of the contracting effect induced by 4-aminopyridine and 3,4-diaminopyridine in guinea-pig isolated ileum. 4. It is concluded that the aminopyridines exert their effects through the release of acetylcholine from parasympathetic nerve terminals.
Velasco
A
A
Department of Pharmacology, Faculty of Medicine, Valladolld, Spain.
Maroto
M
M
Dueñas
A
A
Carvajal
A
A
Fernández de la Gándara
F
F
Nieto
A
A
D015761:4-Aminopyridine / Q000031:analogs & derivatives* / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D000109:Acetylcholine / Q000378:metabolism; D000077770:Amifampridine; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D002121:Calcium Channel Blockers / Q000494:pharmacology; D003981:Diazoxide / Q000494:pharmacology; D004110:Diltiazem / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D005260:Female; D005444:Flunarizine / Q000494:pharmacology; D006168:Guinea Pigs; D007082:Ileum / Q000187:drug effects* / Q000378:metabolism; D066298:In Vitro Techniques; D007811:Lanthanum / Q000494:pharmacology; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects*; D009543:Nifedipine / Q000494:pharmacology; D010275:Parasympathetic Nervous System / Q000187:drug effects / Q000378:metabolism; D010276:Parasympatholytics / Q000494:pharmacology; D015221:Potassium Channels / Q000187:drug effects*; D014665:Vasodilator Agents / Q000494:pharmacology; D014700:Verapamil / Q000494:pharmacology
D002121:Calcium Channel Blockers; D010276:Parasympatholytics; D015221:Potassium Channels; D014665:Vasodilator Agents; C028521:lanthanum chloride; D007811:Lanthanum; D001285:Atropine; D015761:4-Aminopyridine; D014700:Verapamil; D004110:Diltiazem; D009543:Nifedipine; D000109:Acetylcholine; D003981:Diazoxide; D005444:Flunarizine; D000077770:Amifampridine