PHARMACOLOGICAL MODULATION OF THE CARDIOVASCULAR-RESPONSE TO HYPERTONIC NACL INJECTION IN THE ANTEROVENTRAL AREA OF THE RAT-BRAIN 3RD VENTRICLE

The anteroventral area of the rat brain third ventricle (AV3V) was sti mulated by stereotaxically placed microinjections (1 mu l) of hyperton ic 1.5 mol/l NaCl and the responses of mean arterial pressure (MAP) an d heart rate (HR) were recorded, Previous injection of terazosin or pr opranolol (5.0 mu g) into AV3V, 15 min before 1.5 mol/l NaCl microinje ction, did not alter the cardiovascular response pattern induced by 1. 5 mol/l NaCl, Prior AV3V treatment with ketanserin (1.0 mu g) signific antly reduced (p < 0.01) the MAP and HR increase induced by 1.0 mu l o f 1.5 mol/l NaCl without changing basal cardiovascular parameters, Pri or AV3V treatment with losartan (10.0 mu g) significantly reduced (p < 0.01) the hypertension and tachycardia induced by hypertonic NaCl adm inistration, Thus, AV3V serotonin and angiotensin II-sensitive neurons may exert an excitatory role on blood pressure and HR involved with t he sympathetic discharge produced by hypertonic NaCl stimulation.