Angiotensin II receptors in the rat lung are of the AII-1 subtype.
In the rat lung [3H]angiotensin II ([3H]AII) recognizes a single class of binding sites with an equilibrium constant (KD) of 2.8 +/- 0.9 nM. The corresponding receptor density (Bmax) was 704 +/- 60 fmol/mg protein. Equilibrium of [3H]AII binding was reached after 60 min. The dissociation of the radioligand was strongly influenced by mono- and divalent cations and the non-hydrolyzable GTP analog 5'-guanylyl-imido-diphosphate (Gpp[NH]p), indicating the interaction with a G protein. Specific binding of [3H]AII to rat lung preparations was inhibited by different agonists and antagonists and sensitive to DuP 753 (2-n-butyl-4-chloro-5-hydroxymethyl-1-[(2'-(1H-tetrazol-5-yl)bi phe nyl-4-yl) methyl]imidazol, potassium salt) but insensitive to PD 123177 (1-(4-amino-3-methyl-benzyl)-5-diphenylacetyl-4,5,6,7-tetrahydro-i midazo [4,5-c]pyridine-6-carboxylic acid) two non-peptide AII antagonists selective for either the AII-1 or AII-2 subtype. Furthermore, specific [3H]AII binding was inhibited by dithiothreitol. It is concluded that in the rat lung [3H]AII binds to receptors of the AII-1 subtype which are coupled to a G protein. These receptors may be involved in the regulation of pulmonary perfusion and resistance.
Entzeroth
M
M
A Biochemical Research, Dr. Karl Thomae GmbH, Biberach/Riss, F.R.G.
Hadamovsky
S
S
D000804:Angiotensin II / Q000037:antagonists & inhibitors / Q000378:metabolism*; D057911:Angiotensin Receptor Antagonists; D000818:Animals; D001667:Binding, Competitive / Q000187:drug effects; D006165:Guanylyl Imidodiphosphate / Q000494:pharmacology; D066298:In Vitro Techniques; D007700:Kinetics; D008168:Lung / Q000378:metabolism*; D008274:Magnesium / Q000494:pharmacology; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D011945:Receptors, Angiotensin / Q000378:metabolism*; D012964:Sodium / Q000494:pharmacology
D057911:Angiotensin Receptor Antagonists; D011945:Receptors, Angiotensin; D000804:Angiotensin II; D006165:Guanylyl Imidodiphosphate; D012964:Sodium; D008274:Magnesium