Central adrenergic mechanisms in hemorrhage-induced vasopressin secretion.

The effect of central administration of specific adrenergic agonists and antagonists on hemorrhage-induced vasopressin secretion was studied in conscious rats. The intracerebroventricular (icv) injection of the alpha 2-antagonist yohimbine, the alpha 1-antagonist corynanthine, or the beta-agonist isoproterenol failed to alter the vasopressin or blood pressure responses to two sequential 10% reductions in blood volume. Administration of the beta-antagonist propranolol, however, resulted in a significant attenuation of the vasopressin response to hemorrhage, with little effect on the blood pressure response. The alpha 2-agonist, butylated hydroxytoluene (BHT) 933, caused an enhanced vasopressin response to hemorrhage, with a resulting improved maintenance in blood pressure. The results indicate that both alpha 2- and beta-adrenoreceptors may be involved in the pressure-volume control of vasopressin secretion.