Overlapping distribution of receptors for atrial natriuretic peptide and angiotensin II in the kidney and the adrenal gland of the freshwater turtle, Amyda japonica.
The distribution of receptors for atrial natriuretic peptide (ANP) and angiotensin II (ANG II) in the kidney and adrenal gland of the freshwater turtle, Amyda japonica, was examined by quantitative in vitro autoradiography using 125I-labeled rat (r)ANP1-28 and 125I-labeled human ANG II as labeled ligands. Receptor subtypes were characterized by competition with des[Gln18,Ser19,Gly20, Leu21, Gly22] ANP(4-23) (C-ANP) as a selective ligand of the clearance receptors to specific 125I-rANP(1-28) binding, and with DuP 753 and PD 123319 as nonpeptide antagonists for ANG II receptors type 1 (AT1) and type 2 (AT2) subtypes, respectively, to 125I-ANG II binding. Specific 125I-rANP(1-28) binding with a single binding site was found overlying glomeruli of the kidney and the outer zone of the adrenal gland with dissociation constants (Kd) of 4.39 +/- 0.33 and 6.07 +/- 1.36 nM, respectively. C-ANP (10 microM) inhibited about 90% of the glomerular and adrenal 125I-rANP(1-28) binding. Specific 125I-ANG II binding was also localized in the glomeruli of the kidney and the outer zone of the adrenal gland with Kd of 1.02 +/- 0.22 and 0.37 +/- 0.04 nM, respectively. DuP 753 (10 microM) potently inhibited about 80% of glomerular and 90% of adrenal 125I-ANG II binding, whereas PD 123319 (10 microM) was very weak in competing for specific 125I-ANG II binding in both tissues. Therefore, these results indicate that specific ANP and ANG II receptors with high affinities have an overlapping distribution in glomeruli of the kidney and the outer zone of the adrenal gland of the freshwater turtle. They also suggest that biological and clearance ANP receptor-like subtypes coexist in both tissues, and the predominant ANG II receptor subtype in these tissues is the AT1-like receptor. The overlapping distribution of specific receptors for both peptides in these tissues provides the basis for possible receptor interactions to exert a functional antagonism between ANP and ANG II in the freshwater turtle.
Kim
S Z
SZ
Department of Physiology, Medical School, and Institute for Medical Sciences, Jeonbug National University, Jeonju, 561-180, Republic of Korea.
Kim
S H
SH
Cho
K W
KW
D000311:Adrenal Glands / Q000201:enzymology / Q000378:metabolism*; D000804:Angiotensin II / Q000378:metabolism*; D000818:Animals; D001345:Autoradiography; D003720:Densitometry; D005260:Female; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D007457:Iodine Radioisotopes; D007668:Kidney / Q000201:enzymology / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D011945:Receptors, Angiotensin / Q000378:metabolism*; D017461:Receptors, Atrial Natriuretic Factor / Q000378:metabolism*; D014426:Turtles / Q000378:metabolism*
D007457:Iodine Radioisotopes; D011945:Receptors, Angiotensin; D000804:Angiotensin II; D017461:Receptors, Atrial Natriuretic Factor