[Effects of dauricine on slow action potentials in myocardium].
The effects of dauricine were examined on the slow action potentials induced by both high K+ (24 mmol/L) or TTX (40 mumol/L) in guinea pig papillary muscles and in sinoatrial node cells of rabbit. Dauricine 40 mumol/L decreased the maximal upstroke velocity (Vmax) of slow action potentials and prolonged the action potential duration at 50% repolarization (APD50). Bay K 8644 (50 nmol/L) increased the amplitude and Vmax of slow action potentials, which were antagonized by dauricine (40 mumol/L). An inhibitory influence of dauricine on the action potential amplitude was observed in papillary muscles superfused with Tyrode's solution containing high K+ and in rabbit sinoatrial node cells, but it was not with TTX. The resting potentials of the 3 slow action potentials were not affected by dauricine. The results suggest that dauricine possesses calcium-antagonistic effect.
Zong
X G
XG
Department of Pharmacology, Tongji Medical University, Hankou, China.
Jiang
M X
MX
D000200:Action Potentials / Q000187:drug effects; D000470:Alkaloids; D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology*; D044182:Benzylisoquinolines; D002121:Calcium Channel Blockers / Q000494:pharmacology; D005260:Female; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007546:Isoquinolines / Q000494:pharmacology*; D008297:Male; D010210:Papillary Muscles / Q000187:drug effects*; D011817:Rabbits; D012849:Sinoatrial Node / Q000187:drug effects; D044005:Tetrahydroisoquinolines
D000470:Alkaloids; D000889:Anti-Arrhythmia Agents; D044182:Benzylisoquinolines; D002121:Calcium Channel Blockers; D007546:Isoquinolines; D044005:Tetrahydroisoquinolines; C035934:dauricine