Characterization of tachykinin receptors in endothelial cells of porcine artery.

The binding of iodine-labeled Bolton-Hunter substance P (125I-BHSP) to porcine endothelial cell membranes was examined. The endothelial cells had a single high-affinity binding site with a dissociation constant of 0.10 nM, and a maximum number of binding sites of 52.2 fmol/mg protein. The relative potencies of various tachykinins to displace the binding of 47 pM 125I-BHSP suggested that endothelial cells of porcine aorta contain the NK-1 subtype of tachykinin receptor. A GTP analogue, guanyl-5'-yl imidodiphosphate, induced marked reduction in the number of 125I-BHSP binding sites suggesting that these binding sites are coupled with GTP-binding protein.