Blood pressure and heart rate effects of kynuramine in pithed rats.

Kynuramine increased heart rate and blood pressure in pithed rats. Heart rate responses were blocked by beta-adrenoceptor antagonists and reserpine pretreatment. Both of these treatments reduced the pressor responses to kynuramine. Remaining pressor activity was inhibited by phentolamine. The pressor responses to kynuramine were reversed to depressor responses during infusion of norepinephrine but not vasopressin. It is concluded that kynuramine releases cardiac catecholamines and acts as a partial agonist on vascular alpha-adrenoceptors.