[3H]vasopressin binding to rat hippocampal synaptic plasma membrane. Kinetic and pharmacological characterization

Characterization of specific vasopressin binding sites to rat hippocampal membranes has been assayed using tritiated lysine-vasopressin labelled on the tyrosyl residue. At 30 degrees C specific [3H]vasopressin binding was saturable. The estimated equilibrium dissociation constant was 7.1 nM, the mean maximal binding capacity was 78 fmol/mg protein. Arginine-vasopressin has a high affinity (Kd = 2.8 nM) and dDAVP has a low affinity (Kd = 249 nM) for hippocampal synaptic membranes. (OH)AVP and Phe2Orn8VT are at least as active as AVP in inhibiting [3H]vasopressin binding. Adenylate cyclase was activated by VIP and inhibited by PIA, but not affected by lysine-vasopressin.