Abstract
The methods of basolateral membrane isolation from rat kidney and ³H-AVP receptor assay using this basolateral membrane preparation were established. Then, the effects of analogues and drugs on AVP-receptor binding were studied. Specific ³H-AVP binding was inhibited by LVP, dDAVP and oxytocin in that order. Among the various agonistic or antagonistic drugs to AVP (fluoride, cyclophosphamide, mechlorethamine, chlorpropamide), only chlorpropamide inhibited ³H-AVP binding to the membrane. The Kd value calculated by Scatchard analysis was 1.30±0.28 nM (n＝4, M±SD), and it was increased to 2.69±0.32 nM (n＝5, M ±SD) by adding 1mM of chlorpropamide, while BMAX was unchanged. Our data show that 1 mM chlorpropamide decreases receptor affinity for AVP, and alters AVP-receptor binding in a competitive manner.
