REGIONAL VASCULAR AND CARDIAC RESPONSES TO SYSTEMIC NEUROPEPTIDE-Y INNORMAL AND DIABETIC RATS

Diabetes is associated with altered autonomic activity, and both the p eripheral and central nervous content of NPY is altered in diabetes su ggesting that part of the cardiovascular dysfunction of diabetes may b e associated with altered responses to NPY. We evaluated the mean arte rial pressure (MAP), heart rate (HR) and regional blood flow (BF) in r esponse to NPY in normal and diabetic rats. Male Wistar rats were made diabetic using streptozotocin and maintained without insulin treatmen t for 28-30 days. Normal and diabetic animals were anesthetized, the f emoral artery cannulated, and flow probes placed around the iliac, ren al and superior mesenteric arteries. Dose dependent responses to NPY i nfusion were determined for MAP, HR and BF. Conductance was calculated from BF/MAP. In normal rats NPY increased the MAP in a dose-dependent fashion but did not alter the HR. NPY decreased the BF in the iliac a rtery in a dose-dependent fashion while the renal BF was decreased onl y at the highest dose, and the superior mesenteric BF was not affected . The conductances in all vascular beds were decreased dose dependentl y. NPY in diabetic rats also increased MAP and did not affect HR. In d iabetic rats NPY also decreased BF in the iliac and renal arteries but contrastingly increased BF in the superior mesenteric artery. Again c onductances in all three vascular beds were decreased by NPY. When com paring diabetic response to NPY to normals we noted that the MAP respo nse was less in the diabetic, but the IIR and regional BF were not dif ferent. The vascular conductances in response to NPY were attenuated i n the diabetic vessels especially the iliac and superior mesenteric. W e conclude that systemic NPY increases MAP as a result of decreased va scular conductance and this vasopressive effect of NPY is diminished i n diabetics. (C) 1997 Elsevier Science Inc.