Adenosine A1 receptor and its gene expression in ventricles from spontaneously hypertensive rats.
We characterized the adenosine A1 receptor and the levels of its mRNA expression in the ventricles of 6- and 13-wk-old Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR). The binding of 2-chloro-[3H]cyclopentyladenosine ([3H]CCPA), an A1 agonist ligand, to ventricular membranes was saturable and reversible. The receptor density was significantly lower in SHR than in WKY at 13 wk. The dissociation constant values were not different among these groups. In Northern blot analysis using rat A1 receptor cDNA, levels of mRNA did not differ significantly in the two groups at 13 wk, but the level in SHR significantly exceeded that in WKY at 6 wk. Because plasma adenosine levels were reported to be increased at 13 wk in SHR and we found mRNA levels were similar at this age, the discrepancy between A1 receptor density and its mRNA levels might be related to the desensitization of A1 receptors. Although the implication of this decreased density of A1 receptors is not known, it may involve an increased susceptibility to ischemia.
Kobayashi
S
S
Second Department of Internal Medicine, Yokohama City University, School of Medicine, Japan.
Umemura
S
S
Toya
Y
Y
Hirawa
N
N
Hayashi
S
S
Uchino
K
K
Ishii
M
M
D000818:Animals; D015152:Blotting, Northern; D015870:Gene Expression; D008297:Male; D009206:Myocardium / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D011869:Radioligand Assay; D051381:Rats; D011918:Rats, Inbred SHR / Q000235:genetics* / Q000378:metabolism*; D011921:Rats, Inbred WKY / Q000235:genetics / Q000378:metabolism; D018047:Receptors, Purinergic P1 / Q000235:genetics* / Q000378:metabolism*; D016276:Ventricular Function
D012333:RNA, Messenger; D018047:Receptors, Purinergic P1