High calcium diet effectively opposes the development of deoxycorticosterone-salt hypertension in rats.
The effects of increased dietary calcium intake on blood pressure and arterial function were investigated in one-kidney deoxycorticosterone-salt hypertensive Wistar rats. The calcium content of the control diet was 1.1%, and that of the high calcium diet, 2.5%. During the 10-week study calcium supplementation markedly attenuated the steroid-salt-induced rise in blood pressure and the associated cardiac hypertrophy. Responses of mesenteric arterial rings in vitro were examined at the end of the study. In deoxycorticosterone-salt-treated rats, the contractile sensitivity of endothelium-denuded preparations to norepinephrine, 5-hydroxytryptamine, and KCl, and the inhibitory effect of nifedipine on KCl-evoked responses were enhanced. It is interesting that the high calcium diet alleviated the steroid-salt-induced increase in sensitivity to KCl but did not significantly affect it to the receptor-mediated agonists norepinephrine and 5-hydroxytryptamine. Thus, sensitivity to membrane depolarization was reduced by calcium supplementation. Smooth muscle responses were also studied by challenging the preparations with KCl in a calcium-free solution, after which calcium was added to the organ bath in increasing concentrations. In steroid-salt-treated rats, these calcium contractions were attenuated, but concomitant calcium supplementation normalized the responses, suggesting improved cell membrane handling of calcium. In addition, the mineralocorticoid-salt treatment impaired relaxation responses of endothelium-intact arterial rings to acetylcholine, sodium nitroprusside, and isoproterenol.(ABSTRACT TRUNCATED AT 250 WORDS)
Mäkynen
H
H
Department of Biomedical Sciences, University of Tampere, Finland.
Arvola
P
P
Vapaatalo
H
H
Pörsti
I
I
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002118:Calcium / Q000494:pharmacology; D002136:Calcium, Dietary / Q000008:administration & dosage*; D006332:Cardiomegaly / Q000139:chemically induced / Q000178:diet therapy; D003900:Desoxycorticosterone / Q000031:analogs & derivatives* / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000502:physiology; D006973:Hypertension / Q000139:chemically induced / Q000178:diet therapy* / Q000503:physiopathology; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D008638:Mesenteric Arteries; D009599:Nitroprusside / Q000494:pharmacology; D009638:Norepinephrine / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D012701:Serotonin / Q000494:pharmacology; D012965:Sodium Chloride / Q000494:pharmacology*; D014661:Vasoconstriction / Q000187:drug effects
D002136:Calcium, Dietary; C019323:deoxycortone pivalate; D009599:Nitroprusside; D012701:Serotonin; D003900:Desoxycorticosterone; D012965:Sodium Chloride; D011189:Potassium Chloride; D007545:Isoproterenol; D000109:Acetylcholine; D002118:Calcium; D009638:Norepinephrine