METABOLIC AND ENDOCRINE EFFECTS OF FASTING FOLLOWED BY INFUSION OF 5-PERCENT GLUCOSE

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  • 1 January 1981
    • journal article
    • research article
    • Vol. 90  (5) , 810-816
Abstract
Isotonic glucose is often the sole nutrient provided to hospitalized patients with varying degrees of protein calorie malnutrition. To study the effects of such diets uncomplicated by illness, normal human subjects were fasted (6-14 days) before receiving an infusion of 5% dextrose (5-7 days). Norepinephrine excretion rose steadily to 6 times control values during the first 6 days of the fast and changed little thereafter. It remained high during the first 3 days of glucose infusion and subsequently returned toward normal. The rate of N.tau.-methylhistidine excretion changed little during the fast but decreased abruptly with glucose infusion. The magnitude of N.tau.-methylhistidine excretion indicated that unidirectional muscle protein degradation was about equal to N excretion during the fast, and that the decrease in muscle protein degradation could account for the abrupt decrease in N excretion (from 91 to 30 mg N/kg .cntdot. day) after glucose infusion. This suggests that the conservation of muscle protein caused by glucose infusion in this setting is affected by decreased degradation rather than by increased synthesis. Changes in N.tau.-methylhistidine excretion and total N excretion were more rapid than, and therefore not mediated by, changes in insulin concentration or norepinephrine excretion.