The effect of cimetidine on liver blood flow in anesthetized man.

In eight patients subjected to abdominal surgery, the effect of intravenous cimetidine (Tagamet) on hepatic arterial blood flow and portal blood flow was studied, utilizing electromagnetic blood flowmetry. Following cimetidine an increase in hepatic arterial blood flow concomitant with a decrease in mean arterial pressure were detected. Calculated hepatic artery vascular resistance was therefore significantly decreased by 28% after 2 min and 17% after 10 min. There was no change in portal blood flow. It is suggested that this effect of cimetidine is due to increased plasma histamine levels after acute H2 receptor blockade.