Long-lasting actions of Bay K 8644 on responses of guinea pig taenia coli.
1. Bay K 8644, a dihydropyridine Ca2+ agonist, (10(-6) M), induced strong rhythmic contractions in taenia coli and induced a contracture after about 5.5 hr of the application. Increases in Bay K 8644 concentrations prolonged the period of rhythmic contractions and slowed the onset of the contracture. 2. Nifedipine, a dihydropyridine Ca2+ antagonist, inhibited the delayed contracture to Bay K 8644 more than the initial rhythmic contractions. The contracture to Bay K 8644 may be preferentially dependent on extracellular Ca2+ entry in comparison with the rhythmic contractions in taenia coli.
Nasu
T
T
Department of Veterinary Pharmacology, Faculty of Agriculture, Yamaguchi University, Japan. nasu@agr.yamaguchi-u.ac.jp
Sasaki
M
M
Shibata
H
H
D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology*; D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology; D003106:Colon / Q000187:drug effects*; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects*; D009543:Nifedipine / Q000494:pharmacology; D013997:Time Factors
D002121:Calcium Channel Blockers; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D009543:Nifedipine