Inhibition of histamine-stimulated increases in heart rate in man with the H2-histamine receptor antagonist cimetidine.

The influence of an H2-histamine receptor antagonist, cimetidine, on histamine-induced changes in heart rate and blood pressure was examined in a randomized double-blind study in six fasted male subjects. The intravenous infusion of histamine (10 microgram/min) for 20 minutes caused an immediate and sustained increase in heart rate (26 per cent and a transient fall in mean arterial blood pressure (10 per cent). Cimetidine pretreatment (300 mg intravenously) inhibited histamine-elevated heart rate by 75 per cent (P less than 0.05) and histamine-decreased blood pressure by 54 per cent (P less than 0.05). Cimetidine by itself did not cause significant changes in heart rate or blood pressure. These results illustrate that H2-histamine receptor antagonists significantly inhibit histamine-induced increases in heart rate in man and support the potential use of cimetidine in certain cases of tachyarrhythmia.