We aimed to characterize endothelin (ET) receptors in the swine intestinal vasculature and to determine ischemia-reperfusion (I/R) effects on these receptors. Saturation and competitive binding assays were performed on mesenteric artery protein membranes from 1- and 40-day-old animals, both control and those subjected to 1 h of partial ischemia followed by 6 h of reperfusion in vivo. Scatchard analysis of saturation binding with ¹²⁵I-labeled ET-1 in membranes from endothelium-denuded (E) vessels revealed that the maximum number of binding sites was greater in younger animals. Competitive ¹²⁵I-ET-1 binding was significant for a one-site model with ET-1, ET-3, and sarafotoxin S6c (S6c) in membranes from endothelium-intact (E⁺) and E vessels in both age groups. The maximum number of ET-1 binding sites was significantly greater in younger animals. In the presence of the ET_A receptor antagonist BQ-123, competitive ¹²⁵I-ET-1 binding was significant for a one-site model with ET-1 and S6c in membranes from E⁺ vessels in both age groups. The maximum number of ET-1 binding sites was significantly greater in younger animals. After I/R, the maximum number of ET-1 binding sites was unchanged. In the presence of BQ-123, specific binding by ET-1 and S6c was eliminated in both age groups after I/R. These results suggest that both ET receptor populations are expressed to a greater degree in younger animals and I/R significantly affects the ET_B receptor.