Two renal. cap alpha. /sub 2/-adrenergic receptor sites revealed by of-aminoclonidine binding

Journal Article · Sun Feb 01 00:00:00 EST 1987 · Am. J. Physiol.; (United States)

OSTI ID:5445290

Sripanidkulchai, B; Dawson, R; Oparil, S; Wyss, J M

(/sup 3/H)p-aminoclonidine (/sup 3/H)PAC, a specific ..cap alpha../sub 2/-adrenergic agonist, was used to characterize ..cap alpha../sub 2/-adrenoceptor binding in rat renal membranes. Rosenthal plots demonstrated two binding sites with K/sub dS/ of approx. 1.7 and 14.2 nM and B/sub max/S (maximum binding) of 47.3 and 218.8 fmol/mg protein for the high- and low-affinity sites, respectively. These characteristics were confirmed by estimate of K/sub d/ parameters based on association and dissociation experiments. Pseudo-Hill coefficients generated from drug inhibition experiments were all less than unity, suggesting differential binding at two ..cap alpha../sub 2/-adrenoceptor binding sites. Specific ..cap alpha../sub 2/-adrenergic agonists exhibited greater binding affinity to both sites than did nonspecific drugs, and all drugs displayed greater affinity for the high- than the low-affinity binding site. Both guanyl nucleotides and sodium chloride inhibited (/sup 3/H)PAC binding more at the high-affinity than at the low-affinity site. Renal denervation resulted in significant upregulation of receptor density only at the high-affinity sites with no change in receptor affinity at either site, suggesting that a majority of the ..cap alpha../sub 2/-adrenoceptors in the kidney are postsynaptic. Thus all lines of evidence in this study indicate that two ..cap alpha../sub 2/-adrenoceptor binding sites exist in the rat kidney.

• Research Organization: Univ. of Alabama, Birmingham
• OSTI ID: 5445290
• Journal Information: Am. J. Physiol.; (United States), Vol. 252:2
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
CELL MEMBRANES
CONFIGURATION INTERACTION
SYMPATHOMIMETICS
TRITIUM COMPOUNDS
BIOCHEMICAL REACTION KINETICS
INHIBITION
KIDNEYS
NUCLEOTIDES
RATS
RECEPTORS
TIME DEPENDENCE
ANIMALS
AUTONOMIC NERVOUS SYSTEM AGENTS
BODY
CELL CONSTITUENTS
DRUGS
KINETICS
LABELLED COMPOUNDS
MAMMALS
MEMBRANE PROTEINS
MEMBRANES
ORGANIC COMPOUNDS
ORGANS
PROTEINS
REACTION KINETICS
RODENTS
VERTEBRATES
550201* - Biochemistry- Tracer Techniques