Vascular relaxation probably mediates the antihypertensive effect of a high-potassium diet: a role for enhanced vascular Na,K-ATPase activity.
OBJECTIVE
to evaluate the effect of dietary potassium on blood pressure and vascular contractility in adult rats of two strains, spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats.


METHODS
'Potassium-induced relaxation' was evaluated in aortic rings as a functional measure of Na,K-ATPase activity in the vascular wall. The rats were fed one of three diets: regular (American Institute of Nutrition-76 rat chow); high-sodium (7% sodium chloride) or high-sodium plus potassium (7% sodium chloride and 13.4% potassium citrate) for 12 +/- 1 weeks.


RESULTS
SHR fed the high-sodium diet had a mean blood pressure of 157 +/- 8 mmHg, as compared with 130 +/- 9 mmHg for those on a regular diet (P < 0.01). SHR fed the potassium-supplemented diet had a blood pressure of 122 +/- 9 mmHg (P < 0.01 versus the high-sodium diet group). The mean blood pressure of WKY rats was 78 +/- 3 mmHg and did not differ among the dietary groups. The 'potassium-induced relaxation' response of aortic rings from SHR and WKY rats fed a potassium-supplemented diet was significantly higher (P < 0.05) than that in animals in the corresponding high-sodium dietary group. This observation in potassium-supplemented rats is interpreted as indicative of increased Na,K-ATPase activity in the vascular wall.


CONCLUSIONS
A potassium-rich diet in SHR receiving a high sodium intake was associated with lower blood pressure and higher vascular Na,K-ATPase activity. A similar effect of this diet on vascular Na,K-ATPase was observed in WKY. We propose that the antihypertensive effect of a potassium-rich diet is mediated, at least in part, by stimulation of vascular Na,K-ATPase activity.
Dolson
G M
GM
Renal Section, Veterans Affairs Medical Center and Baylor College of Medicine, Houston 77030, USA.
Wesson
D E
DE
Adrogué
H J
HJ
D000818:Animals; D001011:Aorta / Q000201:enzymology*; D001794:Blood Pressure / Q000502:physiology*; D004032:Diet; D066298:In Vitro Techniques; D011188:Potassium / Q000008:administration & dosage* / Q000494:pharmacology; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D014664:Vasodilation / Q000502:physiology*
D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium