[Effects of N-ethyl perhexiline on His bundle electrogram in rabbits].
N-Ethyl perhexiline (NEP), a drug was synthesized for the first time by Department of Organic Chemistry, Faculty of Chemistry, Beijing University. The effects of NEP on the A-V conduction and intra ventricular conduction were studied in the anesthetized rabbits by recording His bundle electrogram (HBE) and electrocardiogram (ECG). NEP 3 mg.kg-1 iv prolonged A-H, P-R and R-R intervals. When NEP 6 mg.kg-1 was given, the above changes became more significant, with A-H interval from 52 +/- 7 to 65 +/- 9 ms, P-R interval from 65 +/- 6 to 76 +/- 8 ms, R-R interval from 207 +/- 9 to 230 +/- 9 ms, and H-V interval from 19 +/- 3 to 23 +/- 5 ms. The effects of NEP were similar to that of perhexiline, but the effects of NEP on A-H and P-R intervals were stronger. NEP 6 mg.kg-1 iv antagonized shortening effect of nicotinamide 0.5 g.kg-1 on A-H interval in rabbits. When isoproterenol 10 micrograms.kg-1 was given 3 min after NEP 6 mg.kg-1 iv, the A-H interval prolongation induced by NEP was greatly inhibited. The results suggested that the prolongation effects of NEP on A-H, P-R and R-R intervals would be the results of its calcium-channel blockade.