Influence of hypertonic monosaccharide infusions on the release of plasma arginine vasopressin in normal humans.

Six healthy men were investigated to determine the osmotic efficiency of hypertonic monosaccharide solutes on the release of plasma arginine vasopressin (AVP). Twenty percent hypertonic glucose infused at 0.187 mmol/kg body weight/min. over 15 min. increases plasma osmolality but not AVP. In contrast, 20% hypertonic fructose administered identically obtains an increase in both. An initial 71% rise in AVP concentration (p less than 0.01) occurred 10 min. post-infusion accompanied by a peak in plasma osmolality and we did not expect AVP to rise by 336% (p less than 0.01) 45 minutes after infusion as plasma osmolality was returning to baseline values. The first increase in plasma AVP reflects an osmotic efficiency probably resulting from the fact that fructose does not cross the membrane of osmoreceptor cells. The mechanism of the second and unexpected increase is discussed, especially the influence of plasma insulin released as a result of fructose infusion.