Autoradiographic localization and characterization of angiotensin II receptor subtypes in the rat thymus.
Angiotensin II (ANG II) receptors were present in the thymus of newborn rats (179 +/- 34 fmol/mg protein). In newborns, binding was predominantly localized in the trabecula, and was selectively displaced by the AT2 ligand CGP 42112A (83-85%) and to a lower extent by the AT1 antagonist losartan (15-17%), indicating a marked predominance of AT2 receptors. Angiotensin II binding was very low in the cortical and medullary areas in the thymus of newborn rats and was no longer detected in the thymus of 4- and 8-week-old rats. No detectable binding for the ACE inhibitor [125I]351A was observed in the thymus of the rat, regardless of the age studied. Our results indicate a possible role for circulating ANG II during development of the thymus with no clear correlation to lymphocyte maturation.
Corrêa
F M
FM
Section on Pharmacology, National Institute of Mental Health, Bethesda, MD 20892.
De Oliveira
A M
AM
Viswanathan
M
M
Saavedra
J M
JM
D000818:Animals; D001345:Autoradiography; D008297:Male; D007703:Peptidyl-Dipeptidase A / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011945:Receptors, Angiotensin / Q000032:analysis* / Q000378:metabolism; D013950:Thymus Gland / Q000737:chemistry* / Q000254:growth & development
D011945:Receptors, Angiotensin; D007703:Peptidyl-Dipeptidase A