Sodium bicarbonate and sodium chloride: effects on blood pressure and electrolyte homeostasis in normal and hypertensive man

Journal/Book: Journal of Hypertension. 1990; 8: 663-670.

Abstract: To test the hypothesis that NaCl and NaHC03 have divergent effects an blood pressure, we carried out a randomly allocated, placebo-controlled, crossover trial in 10 mildly hypertensive and 10 normal subjects. They ingested a fixed daily basal diet of 60 mmol sodium and chloride, 60 mmol potassium and 14 mmol calcium. After balance was achieved (4 days), the subjects were randomly assigned to drink 3liters/day of a NaHC03-containing mineral water (26.2 mmol/I sodium and 33.03 mmol/I HC03) or a control solution containing equimolar amounts of cations as the chloride salt for 7 days (total daily sodium 138 mmol). All urine was collected. Blood pressure was determined by an automated device. One month later the opposite regimen was followed. NaCl did not influence blood pressure, whereas NaHC03 decreased systolic blood pressure (by 5 mmHg) in the hypertensive subjects. Both regimens decreased plasma renin activity in the hypertensive subjects but did not consistently influence plasma aldosterone or catecholamines. However, urinary calcium excretion, which was greater in hypertensives than in normotensives, and greater in white than in black subjects, increased consistently with NaCl but not with NaHC03. The excretion of urate was not influenced by the regimens; however, urate excretion was consistently greater in whites than in blacks. The data show that NaCl increases calcium excretion whereas NaHC03 does not, even at modest levels of intake. NaCl and NaHC03 may therefore differ in their effects an blood pressure.

Keyword(s): Sodium

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