Effects of taurine on slow action potentials in papillary muscles of guinea pig.
OBJECTIVE
To examine the effects of taurine on the slow action potentials induced by KCl 24 mmol.L(-1) or tetrodotoxin 40 mumol.L(-1) in guinea pig papillary muscles.


METHODS
The transmembrane AP was recorded by a conventional glass microelectrode filled with KCl 3 mmol.L(-1). The muscles were exposed to high K(+)-Tyrode's solution or perfused with Tyrode's solution containing tetrodotoxin. Ouabain was added in order to induce oscillatory afterpotentials.


RESULTS
Taurine 20 mmol.L(-1) decreased the maximal upstroke velocity of slow action potential and prolonged the action potential duration at 50% of repolarization. The amplitude of slow action potential and the maximal upstroke velocity both increased by CaCl(2)3 mmol.L(-1) were antagonized by taurine. Taurine increased the concentration of ouabain for oscillatory afterpotential and prolonged the onset time of oscillatory afterpotential.


CONCLUSIONS
Taurine possesses a calcium antagonistic property.
Li
P
P
Department of Pharmacology, Tianjin Medical University, China.
Kang
Y
Y
Wang
G X
GX
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D005260:Female; D006168:Guinea Pigs; D008297:Male; D010210:Papillary Muscles / Q000187:drug effects* / Q000502:physiology; D011189:Potassium Chloride / Q000037:antagonists & inhibitors; D013654:Taurine / Q000494:pharmacology*; D013779:Tetrodotoxin / Q000037:antagonists & inhibitors
D002121:Calcium Channel Blockers; D013654:Taurine; D013779:Tetrodotoxin; D011189:Potassium Chloride