Abstract
Vasodilatation and vasoconstriction were produced in the crossperfused kidney of anesthetized dogs by intravenous injection of noradrenaline or stimulation of the cervical efferent vagus nerve. The vasomotor responses were evaluated by recording the renal blood flow with an electromagnetic flowmeter together with the systemic arterial pressure and perfusion pressure. Ifydergine and β-TM10 abolished the constrictor and dilator responses, and there was no apparent tendency of specific blocking of either dilator or constrictor response in small doses. Atropine, propranolol, and hexamethonium failed to block the vasodilator response. It is concluded that the only mechanism for eliciting the renal vasodilatation is inhibition of sympathetic constrictor discharge.
