Blood Lipids Affect Rat Islet Blood Flow Regulation

26 27 Pancreatic islet blood perfusion varies according to the needs for insulin secretion. We 28 examined the effects of blood lipids on pancreatic islet blood flow in anesthetized rats. Acute 29 administration of intralipid to anesthetized rats increased both triglycerides and free fatty 30 acids, associated with a simultaneous increase in total pancreatic and islet blood flow. A 31 preceding abdominal vagotomy markedly potentiated this and led acutely to a 10-fold 32 increase in islet blood flow associated with a similar increase in serum insulin concentrations. 33 The islet blood flow and serum insulin response could be largely prevented by pretreatment 34 with propranolol and the selective β3-adrenergic inhibitor SR59230A. The nitric oxide 35 synthase inhibitor L-NAME prevented the blood flow increase, but was less effective in 36 reducing serum insulin. Increased islet blood flow after intralipid administration was also seen 37 in islet and whole-pancreas transplanted rats, i.e. models with different degrees of chronic 38 islet denervation, but the effect was not as pronounced. In isolated vascularly perfused single 39 islets intralipid dilated islet arterioles, but this was not affected by SR59230A. Both the 40 sympathetic and parasympathetic nervous system are important for the coordination of islet 41 blood flow and insulin release during hyperlipidemia, with a previously unknown role for β342 adrenoceptors. 43 44