Heat adaptation and intestinal absorption

ABSTRACT

Xylose excretion tests were performed on rats living under the prevailing tropical conditions and on rats living for four weeks at 4§C. Following an oral dose of 32 mg. of D-xylose the cold adapted rats excreted significantly more xylose than the tropical rats. When the xylose was administered by intraperitoneal injection the two groups had almost identical excretion rates. This combination indicates that cold adapted animals absorb xylose more efficiently than the tropical animals. This effect may be due in part to thyroid stimulation, since xylose absorption is markedly depressed by thiouracil. Increased absorption might be explained by the reported observations of an increase in size of the intestinal tract in cold adapted rats. To see if there was, in addition, a qualitative change, the alkaline phosphatase of the intestinal mucous membrane was estimated. Cold adapted rats had nearly twice the concentration of alkaline phosphatase as thiouracil treated animals (AU)