Dauricine was shown to prolong the HBE A-H, H-V intervals and the V width of anesthetized rabbits in a dose-dependent manner. Dauricine 2.5, 5 and 7.5 mg/kg iv increased the A-H interval by 11 +/- 6, 21 +/- 12 and 33 +/- 14%; prolonged the H-V interval by 22 +/- 9, 34 +/- 22 and 51 +/- 16%; and widened the V by 14 +/- 6, 22 +/- 12 and 27 +/- 11%, respectively. The effect of dauricine on the H-V interval was greater than on the A-H interval. Influence of lidocaine on the His-bundle electrogram was not significant. The effect of dauricine on the H-V interval was weakened when administered in combination with lidocaine (p less than 0.05). Dauricine 7.5 mg/kg prolonged the A-H interval at all stimulation frequencies (300, 335, 375, 430 beats/min). Dauricine increased the atrial effective refractory period (AERP) and the atrial-ventricular (A-V) node functional refractory period (AVNFRP) of the rabbits in dose-dependent manner. Isoprenaline 10 micrograms/kg iv shortened the A-H, H-V intervals and V width, and atropine 3 mg/kg iv partially reduced the A-H interval prolonged by dauricine.(ABSTRACT TRUNCATED AT 250 WORDS)