The angiotensin II receptor of rabbit liver: characterization in isolated hepatocytes and effect of GTP.
A homologous population of specific angiotensin II receptors is present on the cell surface of isolated rabbit hepatocytes. The binding characteristics of [3H]angiotensin II to the cells were: association rate constant (K+1) 0.08 l/nmol per min and dissociation rate constant (K-1) 1.9/min, yielding a dissociation constant (Kd) of 24 nmol/l. A very similar Kd (32 nmol/l) has been derived from saturation binding data which indicate a maximal binding capacity of about 200,000 sites/cell. Analysis of the association binding data to purified liver plasma membranes indicated a Kd of 6 nmol/l in the absence and 30 nmol/l in the presence of GTP. Dissociation was clearly dependent upon the presence of the nucleotide, which shifted the K-1 from 0.12/min to 0.42/min. The studied binding sites are very likely to be involved in the glycogenolytic action of angiotensin II, since a highly significant correlation was established between the biological activity (activation of glycogen phosphorylase) and the binding affinity of a series of agonistic analogues. The reported characteristics of the rabbit hepatic angiotensin II receptors show much similarity with those of rat liver.
Vandekerckhove
A
A
Afdeling Biochemie, Fakulteit Geneeskunde, Katholieke Universiteit Leuven, Belgium.
Keppens
S
S
De Wulf
H
H
D000804:Angiotensin II / Q000378:metabolism*; D000818:Animals; D002478:Cells, Cultured; D006160:Guanosine Triphosphate / Q000494:pharmacology*; D007700:Kinetics; D008099:Liver / Q000378:metabolism*; D011817:Rabbits; D011945:Receptors, Angiotensin / Q000187:drug effects / Q000378:metabolism*; D013997:Time Factors
D011945:Receptors, Angiotensin; D000804:Angiotensin II; D006160:Guanosine Triphosphate