Bombesin-induced stimulation of cardiac parasympathetic innervation

The central nervous system effects of bombesin on cardiovascular function were examined in conscious, freely-moving rats. Intracerebroventricular administration of bombesin elevated mean arterial pressure, reduced heart rate and inhibited cold-induced tachycardia. Adrenalectomy prevented bombesin-induced elevations of mean arterial pressure. In contrast, bombesin-induced bradycardia was neither adrenal-dependent nor a baroreceptor-mediated reflex response to increased arterial pressure. Systemic atropine methyl nitrate treatment attenuated bombesin-induced bradycardia, suggesting that bombesin acts within the central nervous system to stimulate cardiac vagal activity.