[Insulin extraction by the isolated perfused rat liver. The effect of portal insulin mass inflow and the duration of infusion on hepatic extraction and elimination rate of insulin].
Rat liver from well fed Wistar-rats was perfused in vitro at 37 degrees C in a flow-through system with Krebs-Ringer-bicarbonate buffer, pH 7.4, in the presence of 20 vol.-% freshly prepared bovine erythrocytes. After 20 min of liver perfusion, insulin was infused into the portal vein either in form of a three-step profile at different insulin concentrations (every step lasting 20 min) or as a permanent infusion of insulin for 40 min. For each step the percentage of hepatic insulin extraction (%hIEx) and the hepatic insulin removal rate (hIRR) was calculated by means of radioimmunological insulin determination in both input and output of the liver. After a single passage about 53% of the portal insulin input of 68 ng insulin/min (step 1) were removed. The hIRR amounted to 4.1 ng insulin/min X g liver. If the insulin input was then increased to about 320 ng insulin/min (step 2), %hIEx decreased to 28%; under these conditions the hIRR amounted to 9,4 ng insulin/min X g liver. If the portal input of insulin again was reduced to 71 ng insulin/min (step 3), the %hIEx remained at about 28% despite a nearly identical input of insulin (compared with that of step 1). The hIRR was then only 2.2 ng insulin/min X g liver. During a 40 min permanent infusion of insulin (184 ng insulin/min) the %hIEx declines from 61% to about 20% within the first 20 min. Then %hIEx was stabilized at this level. hIRR shows a similar behaviour. These experiments show clearly that the %hIEX as well as the hIRR were changed significantly in dependence on portal insulin-input, on the duration of insulin infusion and in dependence on the extent of insulin load of the liver during perfusion.
D000818:Animals; D066298:In Vitro Techniques; D007328:Insulin / Q000378:metabolism*; D007332:Insulin Infusion Systems; D007700:Kinetics; D008099:Liver / Q000378:metabolism*; D010101:Oxygen Consumption; D010477:Perfusion; D011169:Portal Vein; D011863:Radioimmunoassay; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors
D007328:Insulin
Insulinextraktion durch die isoliert perfundierte Rattenleber. Einfluss des portalen Insulinmasseflusses und der Infusionsdauer auf die hepatische Extraktion und die Eliminierungsrate von Insulin.