Cerebral vascular responsiveness in deoxycorticosterone acetate-salt hypertensive rats.
Alterations in cerebral vascular responsiveness were investigated in deoxycorticosterone acetate (DOCA)-salt hypertensive rats. Initial studies on the passive-force response characteristics of strips of basilar artery revealed no difference between control and DOCA-salt rats. No difference in acetylcholine-induced relaxation was seen between the two groups. The contractile response to KCl was similar in control and DOCA-salt rats. An increase in both threshold and midrange sensitivities to serotonin (5-HT) was seen in basilar artery from DOCA-salt rats. However, extracellular Ca sensitivity in the presence of 10(-6) M 5-HT was not altered. Intracellular Ca release (phasic contraction in response to 10(-6) M 5-HT) was similar in control and DOCA-salt rats. Relaxation in response to Ca (membrane stabilization) was also not different. Whereas sodium nitroprusside (SNP)-induced relaxation was not altered in basilar artery from DOCA-salt rats, a significant decrease in isoproterenol (ISO)-induced relaxation was observed. Relaxation following washout of maximal contractions to KCl and 5-HT was similar in the two groups. These results demonstrate specific alterations in cerebral vascular responsiveness of DOCA-salt rats. Whereas KCl contractile and SNP relaxation responses were not affected, responses to 5-HT and ISO were significantly altered. These changes do not appear to be related to alterations in the endothelium or in the Ca responsiveness of the vascular smooth muscle.
D000818:Animals; D001488:Basilar Artery / Q000187:drug effects / Q000502:physiology / Q000503:physiopathology*; D001794:Blood Pressure; D002118:Calcium / Q000494:pharmacology; D002560:Cerebrovascular Circulation; D003900:Desoxycorticosterone; D006973:Hypertension / Q000139:chemically induced / Q000503:physiopathology*; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009126:Muscle Relaxation / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000503:physiopathology; D009599:Nitroprusside / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000494:pharmacology
D009599:Nitroprusside; D012701:Serotonin; D003900:Desoxycorticosterone; D011189:Potassium Chloride; D007545:Isoproterenol; D002118:Calcium