Net insulin secretion and IRI response to 1 mg glucose during OGTT

Dogs in postabsorbtive state were anesthetized with IV nembutal. Their femoral arteries were catheterized, and the abdomens were entered via a midline incision. A small branch of the pancreatic artery and a corresponding small vein were catheterized. 133Xe was injected through the artery, and the the pancreatic blood flow rate (PBFR) was determined. Net insulin secretion was calculated using the insulin concentration of pancreatic vein-artery difference and pancreatic plasma flow rate (PPFR). After control studies an oral glucose tolerance test (2 g/kg body wt.) was performed. Under control studies the mean value of net insulin secretion was 3,753.2 +/- 699.1 microunits/100 g P/min and the maximum values were 10,610.2 +/- 3,658.7 and 11,108.0 +/- 2,852.6 microunits/100 g P/min at 20 and 60 min after glucose loading, respectively (P less than 0.05). Insulin response per mg of glucose was 83.2 +/- 12.2 microunits under control conditions. Twenty minutes after glucose loading this figure rose to 173.4 +/- 41.7 microunits/mg glucose and at 60 min 207.9 +/- 49.2 microunits/mg glucose.