A study of urinary sodium and potassium excretion rates among urban and rural Zulus and Indians.
ABSTRACT A study was carried out to evaluate the relationship between blood pressure, plasma renin activity, serum aldosterone and patterns of urinary sodium and potassium excretion rates in urban Zulus, rural Zulus and Indians in order to explain the high prevalence of hypertension in the urban adult Zulu (25%) compared to the rural adult Zulu (10%). Urinary sodium and potassium were not significantly different between urban and rural Zulus. There was no association between sodium excretion and blood pressure. Urinary potassium correlated negatively with blood pressure in rural Zulus and Indians but not in urban Zulus. The urinary sodium:potassium ratio was significantly lower in rural Zulus than in urban Zulus. The sodium:potassium ratio of Indians was not significantly different from that of Zulus. Plasma renin activity levels were significantly lower in urban than in rural Zulus. This difference is an enigma but may be due to an environmental factor. Serum aldosterone correlated positively with plasma renin activity and negatively with the urinary sodium:potassium ratio.
Article: Renin-sodium profile and renal prostaglandins in the pathogenesis of systemic arterial hypertension in blacks.[show abstract] [hide abstract]
ABSTRACT: Thirteen black women with systemic (essential) arterial hypertension, age-matched with normotensives, were examined during two protocols inducing sodium depletion and sodium loading respectively. Changes in plasma renin activity (PRA), urinary aldosterone values and prostaglandin E2 (PGE2) and F2a (PGF2a) excretion were simultaneously assessed. Renin profiles, obtained by the plotting of PRA against the urinary excretion of sodium, showed a 62% prevalence of low-renin hypertension, the remaining 38% of the patients having normal-renin hypertension. At basal level the hypertensives had suppressed renal synthesis of vasodilator PGE2 and a non-significant increase in venopressor PGF2a. This was reflected in the significant 32% decrease in the PGE2/PGF2a ratio. This finding was in keeping with their low-renin hypertension. During sodium depletion PG excretion was increased in both normotensive and hypertensive groups. The opposite effect was found during sodium loading. The results of this study do not support a natriuretic role for renal PGE2, but do support the hypothesis that there is decreased renal vasodepressor PGE2 synthesis in black hypertensive patients.South African medical journal = Suid-Afrikaanse tydskrif vir geneeskunde 09/1994; 84(8 Pt 1):491-4. · 2.04 Impact Factor