Pancreatic islet blood flow in conscious rats during hyperglycemia and hypoglycemia

Anesthesia affects general hemodynamics and regulation of organ perfusion. We used colored microspheres to measure pancreatic islet blood flow in cons cious rats at two time points, during either hyperglycemia or hypoglycemia. This method, using black and green microspheres, was validated by comparis on with previous microsphere experiments and by lack of effect of a nonmeta bolizable glucose analog, 3-O-methylglucose, on islet perfusion. Basal and glucose-stimulated islet blood flow levels were similar in pentobarbital so dium-anesthetized and conscious rats. However, the basal distribution of pa ncreatic blood flow was altered by anesthesia (fractional islet blood flow 5.8 +/- 0.4% in conscious rats, 7.9 +/- 0.8% in pentobarbital-anesthetized rats, P<0.05). Insulin-induced hypoglycemia significantly increased whole p ancreatic blood flow in conscious rats, whereas islet blood flow remained u nchanged and fractional islet blood flow was decreased (5.8 +/- 0.5% in the basal state, 4.2 +/- 0.4% during hypoglycemia, P< 0.001). Methylatropine p retreatment significantly increased islet blood flow during hypoglycemia by 181%. This result suggests that prevention of hypoglycemia-induced increas e in islet perfusion may be mediated, at least in part, by a cholinergic, v agal muscarinic mechanism.