Ethnic differences of renin-sodium profile and renal prostaglandins in the pathogenesis of systemic arterial hypertension.
OBJECTIVE
To compare renin-sodium profile and renal prostaglandins (PGs) of Black normotensive and hypertensive patients, with the same parameters of Caucasian normotensives and hypertensives, e.g. to reveal some of the ethnic differences in the pathogenesis of systemic (essential) hypertension.


METHODS
27 Black Zimbabwean normotensive and 27 hypertensive patients were matched by age, sex and number to Caucasian normotensives and hypertensives (systolic blood pressure > 160 mm Hg or diastolic blood pressure > 95 mm Hg, or both). All were examined during two protocols producing sodium depletion (less than 40 mmol sodium diet/day) for five days, followed by sodium loading (300 mmol sodium diet/day) for another five days. Changes in plasma renin activity (PRA), urinary aldosterone (Aldo), prostaglandin E2(PGE2) and prostaglandin F2 alpha (PGF2 alpha) excretions were simultaneously assessed by radioimmunoassay.


RESULTS
Compared to caucasians the Blacks showed similar basal aldosterone and Na+ excretion but significant Na+ retention (30pc) during Na+ loading. Their basal PRA was lower (32pc) and poorly responding to sodium depletion/loading. They had suppressed PG synthesis, the PGE2/PGF2 ratio being significantly decreased 11pc. Renin profiles, obtained by plotting PRA against urinary Na+ excretion showed prevalence of low renin hypertension (62pc) in Black patients. All Caucasian patients had normal renin hypertension. At basal level the Black hypertensives had suppressed synthesis of vasodilator PGF2/PGF2 alpha ratio by 32pc. This finding was in accordance with their low renin hypertension. During sodium depletion the PGs excretion was increased in both hypertensive groups. The opposite effect was found during sodium loading.


CONCLUSIONS
This study shows ethnic differences in renin-sodium profile and renal PG synthesis, during changes in dietary sodium. It addresses an old medical controversy about the usefulness of renin profiling in identifying hypertensive patients who are at increased risk for heart attack (Whites with normal/high renin hypertension) or increased risk of stroke (Blacks with low renin, sodium mediated hypertension).
Somova
L
L
Department of Human Physiology and Physiological Chemistry, University of Durban-Westville, South Africa.
Mufunda
J
J
D000328:Adult; D000450:Aldosterone / Q000652:urine; D044383:Black People; D016022:Case-Control Studies; D015237:Dinoprost / Q000097:blood*; D015232:Dinoprostone / Q000097:blood*; D005260:Female; D006801:Humans; D006973:Hypertension / Q000097:blood* / Q000208:ethnology*; D008297:Male; D012083:Renin / Q000097:blood*; D012964:Sodium / Q000097:blood*; D044465:White People
D000450:Aldosterone; D012964:Sodium; D015237:Dinoprost; D012083:Renin; D015232:Dinoprostone