Cerebral intraventricular 6-hydroxydopamine prevents vascular changes in the mineralocorticoid hypertensive rat.
The effect of cerebral intraventricular administration of 6-hydroxydopamine (6-OHDA) on blood pressure and vascular smooth muscle responsiveness in deoxycorticosterone acetate (DOCA)-treated rats was assessed. Rats treated with 6-OHDA and DOCA had significantly lower systolic blood pressures (142 +/- 8 mm Hg) than rats treated with DOCA alone (185 +/- 5 mm Hg). After 5 weeks of DOCA treatment, femoral arteries and aortae were excised from these rats, cut helically into strips, and placed in a muscle bath to record isometric force. Dose-response curves to serotonin were shifted to the left in femoral arteries from DOCA-treated rats compared to both control and 6-OHDA-DOCA-treated rats (ED50: DOCA = 6.8 X 10(-8) M, control = 27.9 X 10(-8) M, 6-OHDA-DOCA = 13.4 X 10(-8) M). Arachidonic acid, the prostaglandin precursor, produced greater maximal contractions in femoral artery strips of DOCA-treated rats (358 +/- 56 mg) than in those from controls (115 +/- 31 mg). The maximal response to arachidonic acid in arteries from 6-OHDA-DOCA rats (203 +/- 78 mg) was not different from control values. Ouabain produced a greater maximal response in aortic strips from DOCA rats (658 +/- 165 mg) compared to those from control (196 +/- 72 mg) or 6-OHDA-DOCA (309 +/- 87 mg) rats. We conclude that increased vascular responsiveness to serotonin, arachidonic acid, and ouabain in DOCA hypertensive rats is secondary to a central action of the mineralocorticoid.
D000818:Animals; D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects; D002552:Cerebral Ventricles / Q000187:drug effects*; D003900:Desoxycorticosterone / Q000494:pharmacology*; D006892:Hydroxydopamines / Q000494:pharmacology*; D006973:Hypertension / Q000503:physiopathology*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D010042:Ouabain / Q000494:pharmacology; D016627:Oxidopamine; D051381:Rats; D011919:Rats, Inbred Strains; D014661:Vasoconstriction / Q000187:drug effects
D001095:Arachidonic Acids; D006892:Hydroxydopamines; D016718:Arachidonic Acid; D003900:Desoxycorticosterone; D010042:Ouabain; D016627:Oxidopamine