B2 bradykinin receptor-like binding in rat renomedullary interstitial cells

A particulate fraction from cultured rat renomedullary interstitial cells (RRIC) was prepared for bradykinin (BK) binding studies. Incubation of three radiolabeled BK analogs, 125I-Tyr1]kallidin, 125I-Tyr5]-BK, and 125I-Tyr8]-BK, with the particulate fraction resulted in degradation of these peptides. Assay conditions which prevented hydrolysis of these radiolabeled kinins were determined. Under these conditions, direct binding studies were performed with 125I-Tyr1]kallidin (TlK) as the radioligand. BK binding affinity, apparent Kassoc. = 1.3 X 10(9) M-1, and specificity, determined with 51 BK analogs, were consistent with those expected of a B2 BK receptor.