Release of histamine by sympathetic nerve stimulation in the guinea pig heart and modulation of adrenergic responses. A physiological role for cardiac histamine?

Histamine has been reported to attenuate adrenergic responses in cardiovascular tissues. In guinea pig atria preloaded with [3H]norepinephrine, histamine diminishes the field stimulation-induced efflux of radioactivity; this effect has been attributed to an inhibition of norepinephrine release from nerve endings. To assess the possible physiological relevance of these findings, we have reinvestigated the effects of histamine on cardiac sympathetic responses and on the release of endogenous norepinephrine in the guinea pig heart isolated with its intact sympathetic innervation.

Dysrhythmias caused by histamine release in guinea pig and human hearts.

Histamine is released into the systemic circulation during anaphylaxis, by drugs and by surgical procedures. Studies in animal models have conclusively demonstrated that released cardiac histamine is a major mediator of arrhythmias that occur during anaphylaxis and following the administration of histamine-releasing drugs. Several lines of evidence suggest a similar arrhythmogenic role for cardiac histamine in humans: (1) The human heart is rich in histamine; (2) cardiac histamine can be readily released from human heart in vitro by therapeutic concentrations of drugs; (3) histamine has potent arrhythmogenic effects on the human heart in vitro.