Insulin secretion and sensitivity after partial hepatectomy in the rat

It is known that following partial hepatectomy in the rat hyperinsulinemia evolves, yet glucose intolerance exists. This pattern could be explained by peripheral insulin insensitivity and a compensatory insulin hypersecretion. In the present study, we examined in vivo insulin secretion and sensitivity in partially hepatectomized rats. We found that the increase in plasma insulin levels during i.v. infusion of glucose (10 mg/min) was exaggerated at 1 and 3 days after partial (68%) hepatectomy (P less than 0.001) compared with that in sham-operated controls. In contrast, at days 7 and 14 the plasma insulin response to glucose was not different from that in controls. To study the in vivo insulin sensitivity, a 3-h i.v. infusion of adrenaline, propranolol, glucose, and variable amounts of insulin were given at 3 days after partial hepatectomy. In this model, the ensuing glycemia, being stable during the 3rd hour of infusion, depends on the plasma insulin levels and insulin sensitivity. It was found that the relation between plasma insulin and plasma glucose levels was not different between partially hepatectomized and sham-operated rats. This indicates the same peripheral sensitivity to insulin in these two groups. We conclude that insulin hypersecretion is already evident even at day 1 after partial hepatectomy, whereas after 7 days this hypersecretion has vanished. Furthermore, the study shows that insulin sensitivity is not altered by partial hepatectomy.