NEUROPEPTIDE-Y AND Y-1-RECEPTOR AGONISTS INCREASE BLOOD-FLOW THROUGH ARTERIOVENOUS ANASTOMOSES IN RAT TAIL

The purpose of this study was to characterize neuropeptide Y (NPY)-ind uced vasodilation in the rat tail. Sterile surgical technique was used (with pentobarbital sodium anesthesia) to equip rats with a jugular c atheter and a blind-ended thermocouple reentrant tube next to the caro tid artery. Tail skin and core temperature were measured with thermoco uples during experiments. Tail skin blood flow was monitored with a la ser Doppler flowmeter, and tail total blood flow and volume were measu red with plethysmography. After baseline data were collected, saline, NPY (16, 32, 64, and 128 mu g/kg), [Leu(31) Pro(34)]NPY (63.25 mu g/kg ), or NPY[13-36] (44.7 mu g/kg) was administered intravenously. Tail t otal blood flow volume, and tail skin temperature increased, whereas t ail skin blood flow and core temperature decreased in response to both NPY- and the Y-1-receptor agonist [Leu(31) Pro(34)]NPY but not in res ponse to saline or NPY[13-36]. Studies conducted with the use of color microspheres demonstrated that arteriovenous anastomoses are involved in this NPY-induced vasodilation.