tokens: In vivo injection of bepridil at a dose of 5 mg / kg ( i . v . ) into 6 anaesthetized dogs which had undergone ablation of all the extrinsic cardiac afferent nerve supply , together with a bilateral medullo - adrenalectomy , caused a marked reduction in heart rate which fell from 98 . 7 + / - 4 . 2 beats / min to 76 + / - 5 . 3 beats / min sustained for more than 45 min .