Protective effects of histamine H1 and H2 antagonists, adenosine and hydrocortisone on cardiac anaphylaxis.

Cardiac anaphylaxis was elicited in isolated working guinea pig hearts in the presence of the histamine receptor antagonists pyrilamine and cimetidine, adenosine or hydrocortisone. Histamine antagonists partially inhibited the occurrence of arrhythmias during cardiac anaphylaxis, but did not significantly antagonize the decrease in cardiac function. Adenosine used in combination with pyrilamine and cimetidine manifested an apparent anti-arrhythmic effect, however, the attenuation of cardiac function was still present. In the presence of hydrocortisone plus histamine antagonists, cardiac anaphylaxis, as expressed by arrhythmias and a decrease in cardiac function, was significantly inhibited. The results suggest that when histamine receptor antagonists are used in combination with hydrocortisone, a good protective effect on cardiac anaphylaxis can be achieved.