Maturation-dependent changes of angiotensin receptor expression in fowl.
An angiotensin (ANG) receptor homologous to the type 1 receptor (AT1) has been cloned in chickens (cAT1). We investigated whether cAT1 expression in various tissues shows maturation/age-dependent changes. cAT1 mRNA levels detected in renal glomeruli [in situ hybridization (ISH)] and kidney extract (RT-PCR) are significantly (P < 0.01) higher in 19-day embryos (EB) than in chicks (CH, 2-3 wk) and pullets/cockerels (PL/CK, 14-16 wk). The levels in adrenal glands (concentrated in subcapsular regions) are high in EB and further increased in CH and PL/CK. cAT1 mRNA is also detectable in smooth muscle (SM)/adventitia of EB and CH aorta and in the adventitia, but not SM, from PL/CK aortas. The endothelia from small arteries and arterioles, but not from aorta, express cAT1 mRNA (ISH). In all age groups, ANG II induces profound endothelium-dependent relaxation of abdominal aorta, partly (37-47%) inhibitable (P < 0.01) by Nomega-nitro-l-arginine methyl ester (l-NAME, 10(-4) M), suggesting the presence of ANG receptor in endothelium. l-NAME-resistant ANG II relaxation, examined in a limited number of EB or CH aortas, was reduced by 125 mM K+ or apamin plus charybdotoxin. The results suggest that 1) cAT1 is present in kidney, adrenal gland, and vascular endothelium (heterogeneity exists among arteries) of EB, CH, and PL/CK, and in aortic SM/adventitia of EB/CH but only in adventitia of PL/CK; 2) levels of cAT1 gene expression change during maturation in a tissue-specific manner; and 3) ANG II-induced relaxation may be partly attributable to nitric oxide and potassium channel activation.
Nishimura
H
H
Dept. of Physiology, Univ. of Tennessee Health Science Center, 894 Union Ave., Memphis, TN 38163, USA. nishimur@physio1.utmem.edu
Yang
Y
Y
Hubert
C
C
Gasc
J-M
JM
Ruijtenbeek
K
K
De Mey
J
J
Boudier
H A J Struijker
HA
Corvol
P
P
D000311:Adrenal Glands / Q000196:embryology / Q000254:growth & development / Q000502:physiology*; D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D001012:Aorta, Abdominal / Q000196:embryology / Q000254:growth & development / Q000502:physiology*; D002642:Chick Embryo; D002645:Chickens; D018507:Gene Expression Regulation, Developmental; D017403:In Situ Hybridization; D007678:Kidney Glomerulus / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*; D012333:RNA, Messenger / Q000032:analysis; D044140:Receptor, Angiotensin, Type 1; D011945:Receptors, Angiotensin / Q000235:genetics*; D012084:Renin-Angiotensin System / Q000502:physiology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000502:physiology; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014664:Vasodilation / Q000187:drug effects
D012333:RNA, Messenger; D044140:Receptor, Angiotensin, Type 1; D011945:Receptors, Angiotensin; D014662:Vasoconstrictor Agents; D000804:Angiotensin II