Acetazolamide and ADH, Renin, Aldosterone, and Water Electrolytes at 4100 M in Man,

Abstract : Male volunteers comprised two groups, one (n=7) received acetazolamide (AZ), 250 mg twice daily, a second received placebo (n=6). These subjects were reduced to 6 and 4, respectively, because of acute mountain sickness (AMS). Morning (0700-0800 AM) and evening (2100-2200 PM) blood samples were obtained on various days, and all urine was collected. On day 4, the subjects were transported from sea level (SL) to 4100 M (HA9 over a period of three hours and returned to SL on day 9. Intakes of field rations and water were measured. The subjects lived in tents. AZ resulted in a brief diuresis, natriuresis, and kaliuresis on day 1, but by day 3, the subjects were in normal water and Na balance. Both K and water balance were similar between groups at HA. Na balance was significantly reduced in the A group for all days at HA, probably a consequence of significantly reduced caloric intake in that group. The plasma aldosterone to renin ratio was significantly lower in the PM than AM at SL, and both AM and PM ratios were reduced at HA. Urinary ADH excretion was significantly increased on days 4 and 5 in the placebo group, but only on day 4 in the AZ group, and was significantly lower on day 5 in the AZ group. Thus AZ blunts the ADH response to HA, a possible mechanism of the AMS ameliorative actions of the drug. Keywords: Circadian rhythm, and High altitude.