Altered responses of aortic smooth muscle from Sprague-Dawley rats with salt-induced hypertension.
1. The contractile responses of aortic ring preparations from Sprague-Dawley rats made hypertensive by 6-week dietary salt loading were studied. The test and control diet contained 8.0 and 0.3% NaCl, respectively. Aortic rings from salt-loaded rats showed enhanced sensitivity to noradrenaline (NA) but not to serotonin. Contractile responses to CaCl2 in Ca-free NA-containing medium was significantly enhanced in salt-loaded rats, but was unchanged in K(+)-depolarised medium. K(+)-induced relaxation (a functional indicator of Na-K adenosine triphosphatase activity) was sensitive to 10 mumol/L ouabain and was significantly attenuated in aortic rings from salt-loaded rats. The results suggest that hypertension induced by salt-loading is associated with enhanced sensitivity to NA, increased Ca2+ entry through receptor-operated channels, and impairment of Na-K ATPase enzyme activity.
Obiefuna
P C
PC
Department of Physiology, College of Medicine, University of Lagos, Nigeria.
Ebeigbe
A B
AB
Sofola
O A
OA
Aloamaka
C P
CP
D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects / Q000503:physiopathology; D002122:Calcium Chloride / Q000494:pharmacology; D006973:Hypertension / Q000139:chemically induced / Q000503:physiopathology*; D066298:In Vitro Techniques; D009126:Muscle Relaxation / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000503:physiopathology*; D009638:Norepinephrine / Q000494:pharmacology; D010042:Ouabain / Q000494:pharmacology; D011188:Potassium / Q000097:blood; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000494:pharmacology; D012964:Sodium / Q000097:blood; D012965:Sodium Chloride; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism
D012701:Serotonin; D012965:Sodium Chloride; D010042:Ouabain; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D002122:Calcium Chloride; D011188:Potassium; D009638:Norepinephrine