SENSING BY INTRAHEPATIC MUSCARINIC NERVES OF A PORTAL-ARTERIAL GLUCOSE-CONCENTRATION GRADIENT AS A SIGNAL FOR INSULIN-DEPENDENT GLUCOSE-UPTAKE IN THE PERFUSED-RAT-LIVER

In vivo, insulin increases net hepatic glucose uptake efficiently only in the presence of a portal-arterial glucose gradient, In isolated pe rfused rat livers supplied with a glucose gradient (portal 10 mM/arter ial 5 mM) insulin-induced glucose uptake was blocked by atropine; in l ivers not supplied with the gradient (portal = arterial 5 mM) insulin- dependent glucose uptake was elicited by acetylcholine. Apparently, th e gradient was sensed and transformed into a metabolic signal by intra hepatic nerves, releasing acetylcholine to muscarinic receptors. (C) 1 997 Federation of European Biochemical Societies.