Antagonistic effects of taurine and 4-aminopyridine on guinea pig ileum.
The effects of 4-aminopyridine (4-AP) and of taurine on the guinea pig ileum were examined. Four-AP increases the basal activity from 1.3 to 6.45 cm2/min. This effect is atropine-sensitive and calcium-dependent. Taurine counteracts the effects of 4-AP on muscle contracture in a concentration-dependent manner. In muscles preincubated with 20 mM taurine, the effect of 4-AP decreased about 65%. Taurine added at the time of maximal effect of 4-AP reduced the muscle contracture induced by the drug to the basal levels. Glycine and beta-alanine did not influence the contracture induced by 4-AP, whereas 25 mM gamma-aminobutyric acid (GABA) reduced it by 30%. Taurine reduced the basal muscle activity by 50% but did not affect the contracture induced by exogenously applied acetylcholine.
D015761:4-Aminopyridine; D000109:Acetylcholine / Q000494:pharmacology; D000631:Aminopyridines / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D005260:Female; D006168:Guinea Pigs; D007082:Ileum / Q000187:drug effects*; D009119:Muscle Contraction / Q000187:drug effects*; D013654:Taurine / Q000494:pharmacology*
D000631:Aminopyridines; D013654:Taurine; D001285:Atropine; D015761:4-Aminopyridine; D000109:Acetylcholine; D002118:Calcium