Cardiac adrenergic blockade with DCI in the intact unanesthetized animal

Abstract

Using techniques developed in this laboratory for continuous recording of essential parameters of left ventricular function, the cardiovascular responses of intact unanesthetized animals to intravenous infusions of isoproterenol, epinephrine and norepinephrine, and to exercise and hypothalamic stimulation, have been compared with responses to the same drugs and procedures after adrenergic blockade, first with the dichloro analogue of isoproterenol (DCI), and then with both DCI and phenoxybenzamine. At dosage level of 5 mg/kg, DCI effectively blocked the response to isoproterenol, but had less effect on the response to epinephrine and norepinephrine, and no effect on the response to exercise or central stimulation. The effects of DCI, per se, were dosage-dependent.