VASODEPRESSOR EFFECTS OF EXERCISE ARE ACCOMPANIED BY REDUCED CIRCULATING OUABAIN-LIKE IMMUNOREACTIVITY AND NORMALIZATION OF NITRIC-OXIDE SYNTHESIS

Our object was to evaluate the effects of regular mild exercise on blo od pressure and on circulating level of ouabainlike factors (OLF) and of nitrate anion, an endproduct of nitric oxide (NO)) in humans. We me asured plasma ouabainlike immunoreactivity (OLI) and nitrate ions (NO3 (-)) before and after mild exercise for 3 months' duration in 16 patie nts with essential hypertension, diabetes mellitus, obesity, or hyperl ipidemia Plasma OLI was measured using an amplified ELISA system with anti-ouabain antibody and biotinyl-tyramide. Serum NO3(-) was measured with high-performance liquid chromatography (HPLC) with an anion-exch ange column. With the reverse phase HPLC system with an octa decylsily l silicagel column, the elution volume of plasma OLI of a healthy volu nteer matched that of authentic ouabain in a gradient elution system o f acetonitrile/H2O. Plasma OLI levels decreased significantly by about 34% after mild exercise, and NO3(-) levels tended to be within the re ference interval in normal volunteers. Body weight, diastolic and syst olic blood pressure, serum triglyceride and acetylcholine esterase (a marker of the fatty liver) were significantly decreased (p < 0.01) aft er 3 months of regular mild exercise. The plasma OLI level was signifi cantly correlated with plasma NO3-; there was a trend toward a correla tion with diastolic blood pressure (p = 0.06) before and after regular exercise. Regular mild exercise led to a decrease in plasma levels of OLI, and acetylcholine esterase activity and blood pressure in adult patients. Results suggest that changes in OLF production contribute to the blood pressure regulation seen in patients who exercise regularly .