title: Regulation of (3H) arginine8 vasopressin binding to the rat renal medulla by guanine nucleotides.
abstract: In rat renal medullary membranes, we have examined modulatory effects of guanine nucleotides on binding of arginine8 vasopressin (AVP) to its receptor. Equilibrium binding studies analyzed by an iterative curve fitting program revealed an interaction of (3H) AVP with a single class of binding sites with a dissociation constant of 1.4 +/- 0.2 nM and a binding site concentration of 201 +/- 37 fmol/mg protein (n = 6). With the addition of 100 microM guanylyl-imidodiphosphate (Gpp(NH)p), the binding site concentration was significantly (p less than 0.01) reduced to 151 +/- 36 fmol/mg protein with no change in receptor affinity. The nonhydrolyzable analogues, guanosine-5'-0-(3-thiophosphate) and Gpp(NH)p were the most potent inhibitors of (3H) AVP binding. Guanosine 5'-triphosphate and guanosine-5'-diphosphate were both relatively poor inhibitors. Guanosine-5'-monophosphate and adenosine 5'-triphosphate did not inhibit (3H) AVP binding at concentrations up to 100 microM. Furthermore, 100 microM Gpp(NH)p accelerated the dissociation of (3H) AVP from the receptor. We conclude that guanine nucleotides are important modulators of AVP binding to the V2 receptor subtype in the renal medulla.
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D001127:Arginine Vasopressin / Q000378:metabolism*; D005260:Female; D006150:Guanine Nucleotides / Q000494:pharmacology*; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D006165:Guanylyl Imidodiphosphate / Q000494:pharmacology; D066298:In Vitro Techniques; D007679:Kidney Medulla / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D011945:Receptors, Angiotensin / Q000187:drug effects / Q000378:metabolism; D017483:Receptors, Vasopressin; D013873:Thionucleotides / Q000494:pharmacology
chemical_list: D006150:Guanine Nucleotides; D011945:Receptors, Angiotensin; D017483:Receptors, Vasopressin; D013873:Thionucleotides; D001127:Arginine Vasopressin; D006165:Guanylyl Imidodiphosphate; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate; D000262:Adenylyl Cyclases