Direct identification of the rat hepatocyte arginine8 vasopressin receptor with a radiolabelled V1-selective antagonist.
We compared [3H] arginine8 vasopressin (AVP) and [3H] 1-beta-mercapto-beta, beta-cyclopentamethylene propionic acid, O-methyl tyrosine2, arginine8 vasopressin (d(CH2)5 Tyr(Me)AVP), a selective V1 receptor antagonist, as radioligands for the rat hepatocyte V1 receptor. Both radioligands bound with high affinity to a site in partially purified membranes prepared from Long Evans rat hepatocytes. The binding site concentrations obtained with either radioligand, 608 +/- 101 fmol/mg protein (n = 5) with [3H] AVP and 603 +/- 62 fmol/mg protein (n = 5) with [3H]d(CH2)5 Tyr(Me)AVP, were not significantly (p greater than 0.5) different. Furthermore, the rank order of potency of a series of synthetic vasopressin analogs and related peptides were identical in competition studies using either radioligand and were consistent with a V1 receptor interaction. Our results demonstrate that [3H] d(CH2)5 Tyr(Me)AVP is a suitable radioligand to study the V1 receptor subtype.
Cornett
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Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205.
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D000818:Animals; D001127:Arginine Vasopressin / Q000031:analogs & derivatives* / Q000037:antagonists & inhibitors* / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D008099:Liver / Q000032:analysis*; D008274:Magnesium / Q000494:pharmacology; D008297:Male; D011869:Radioligand Assay; D051381:Rats; D011945:Receptors, Angiotensin / Q000032:analysis*; D017483:Receptors, Vasopressin
D011945:Receptors, Angiotensin; D017483:Receptors, Vasopressin; D001127:Arginine Vasopressin; C025043:vasopressin, 1-(1-mercaptocyclohexaneacetic acid)-2-(O- methyl-L-tyrosine)-8-L-arginine-; D008274:Magnesium