EFFECTS OF 2-(P-DIMETHYLAMINOSTYRYL)PYRIDINE METHYCHOLIDE(DSPM-Cl)ON ECG,LEFT ATRIUM CONTRACTIVITY AND ON PAPILLARY MUSCLE ACTION POTENTIALS

The effects of DSPM-Cl on ECG in rats, on the dose effect curve in guinea pigleft atria and on the fast action potential(AP),high-K⁺depolarized slow action potential(SAP)inguinea pigs papillary muscle were examined electrophysiologically.DSPM-Cl(2 mg·kg^-1showedsignifieant nagative frequency, negative conductivity effect, and prolonged the PP and PR interval. DSPM-Cl(30～50μmol·L(-1)was shown to inhibit left atria contractility and shift the concentra-tion-response curve of Iso and CaCl₂ to the right with PD^2'values of 4.60and 4.13, respectively.Inaddition, DSPM-Cl was found to prolong the duration of action potential 90(APD₉₀)and effectiverefractory peried(ERP),and decrease the maximal upstroke velocity(Vmax)in K⁺-depolarizedguinea pigs papillary muscles.The results suggest that,like verpamil,DSPM-Cl might be a calciumantagonist.