title: The acute regulation of glucose absorption, transport and metabolism in rat small intestine by insulin in vivo.
abstract: The effect of acute changes in insulin concentrations in vivo on the absorption, transport and metabolism of glucose by rat small intestine in vitro was investigated. Within 2 min of the injection of normal anaesthetized rats with anti-insulin serum, lactate production and glucose metabolism were respectively diminished to 28% and 21% of normal and the conversion of glucose into lactate became quantitative. These changes correlated with the inhibition of two mucosal enzymes, namely the insulin-sensitive enzyme pyruvate dehydrogenase, and phosphofructokinase, which was shown by cross-over measurements to be the rate-limiting enzyme of glycolysis in mucosa. The proportion of glucose translocated unchanged from the luminal perfusate to the serosal medium was simultaneously increased from 45% to 80%. All the changes produced by insulin deficiency were completely reversed with 2 min when antiserum was neutralized by injection of insulin in vivo. The absorption and transport of 3-O-methylglucose were unaffected by insulin. It is concluded that glucose metabolism in rat small intestine is subject to short-term regulation by insulin in vivo and that glucose absorption and transport are regulated indirectly in response to changes in metabolism. Moreover, transport and metabolism compensate in such a way as to deliver the maximal 'effective' amount of glucose to the blood, whether as glucose itself or as lactate for hepatic gluconeogenesis.
mesh_terms: D019325:3-O-Methylglucose; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D001786:Blood Glucose / Q000378:metabolism; D005260:Female; D005947:Glucose / Q000378:metabolism*; D006019:Glycolysis / Q000187:drug effects; D007328:Insulin / Q000172:deficiency / Q000494:pharmacology*; D007408:Intestinal Absorption / Q000187:drug effects; D007413:Intestinal Mucosa / Q000201:enzymology; D007583:Jejunum / Q000378:metabolism*; D008757:Methylglucosides / Q000378:metabolism; D010732:Phosphofructokinase-1 / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D001786:Blood Glucose; D007328:Insulin; D008757:Methylglucosides; D019325:3-O-Methylglucose; D010732:Phosphofructokinase-1; D005947:Glucose