American Journal of Clinical Nutrition, Vol 47, 502-508, Copyright © 1988 by The American Society for Clinical Nutrition, Inc

ORIGINAL RESEARCH COMMUNICATIONS

Responses of sodium balance, blood pressure, and other variables to sodium loading in Papua New Guinea highlanders

T Rikimaru, Y Fujita, T Okuda, N Kajiwara, S Miyatani, MP Alpers and H Koishi
Nutrition Research Laboratory, Tokyo Metropolitan Institute of Gerontology, Japan.

For determination of the responses of sodium balance, blood pressure, and other relevant variables to Na loading in people with a low intake of Na, 10 male Papua New Guinea highland subjects were given additional Na at two levels (128 and 256 mmol/d) for 10 d after a 3-d control period of low-Na diet. Na loading caused a marked positive balance of Na, decreases of aldosterone concentration and renin activity in the plasma, and a decrease of urinary aldosterone excretion. The blood pressure, particularly that measured at noon, increased in the latter half of the Na-loading period, the increase being significant in the group given 256 mmol of sodium daily: the systolic and diastolic blood pressure increased from 92 +/- 8 over 56 +/- 7 mm Hg in the control period to 102 +/- 7 over 60 +/- 4 mm Hg in the latter half of the test period (p less than 0.05).