Myocardial Depressant Activity of a Newly Synthesized Dihydropyrimidine Derivative 5-acyl-6-methyl 4(2,3 methylenedioxy) phenyl-2-s-benzyl-1, 4-dihydro Pyrimidine(bk-vii) on Isolated Perfused Rabbit Heart In Comparison with Nifedipine

To investigate the myocardial depressant activity of a newly synthesized dihydropyrimidine derivative 5acyl-6-methyl-4 (2,3methylenedioxy) Phenyl-2-s-benzyl-1,4-dihydropyrimidine (code named as BK-VII) and comparing with nifedipine on Isolated perfused rabbit heart.

Effects of the test compound BK-VII on the amplitude, heart rate and coronary flow on isolated perfused rabbit heart was compared with nifedipine. Observations were made with increasing concentrations of BK-VII and Nifedipine with dimethylsulfoxide (DMSO) as the solvent. Six preparations were used for each dose of BK-VII and nifedipine. Heart rate, amplitude and coronary flow were noted down every minute for five minutes after injection of each drug and control.

On comparing the effects of BK-VII and nifedipine, it was found that both had a negative inotropic and negative chronotropic effect. BK-VII caused significant decrease in heart rate at doses of 26.3 X 10⁻⁵M and 52.6 X 10⁻⁵M by 13.79% and 43.55% respectively, when compared with the baseline. Significant decrease in amplitude and coronary flow with BK-VII was seen at dose of 52.6 X 10⁻⁵M by 84.93% and 52.79% respectively. Nifedipine significantly decreased heart rate and amplitude at all doses with cardiac arrest at a dose of 4.6 X 10⁻⁵M. A significant increase in coronary flow was seen with nifedipine by 9.4% and 13% at doses of 0.5 X 10⁻⁵M and 1.15 X 10⁻⁵M respectively, though this property was lost at higher doses. On comparison, BK-VII produced significant myocardial depression at much higher dose than nifedipine.

BK-VII has calcium channel blocking activity like nifedipine and produced less potent myocardial depression in comparison with nifedipine.