Alpha and beta-adrenoceptors in hypertension. I. Cardiac and renal alpha 1-, beta 1-, and beta 2-adrenoceptors in rat models of acquired hypertension.
To determine whether adrenoceptor changes in genetic hypertension occur primary or secondary to blood pressure elevation, we measured cardiac and renal alpha 1- (by [125I]Be 2254 binding) and beta 1- and beta 2-adrenoceptors (by (-)-[125I]iodocyanopindolol binding) densities in various rat models of acquired hypertension (Dahl S rats on a high-sodium diet, 1-clip-1-kidney (1C-1K) renal hypertensive and DOCA-salt hypertensive rats) in comparison with genetically identical age-matched untreated rats. In addition, alpha 1-adrenoceptors were assessed in spontaneously hypertensive rats (SHR) and in SHR treated with the immunosuppressant cyclosporin A. In heart, no clear pattern of changes in alpha 1- or beta 1- and beta 2-adrenoceptors was obtained. In kidney, however, beta 1- and beta 2-adrenoceptors were increased in all models of hypertension, and a good correlation between renal beta-adrenoceptors and systolic blood pressure was found. In contrast, renal alpha 1-adrenoceptors were only increased in SHR but not in any form of acquired hypertension. Thus, renal beta-adrenoceptor increases probably occur secondary to blood pressure elevation, whereas alpha 1-adrenoceptor increases appear to be associated with genetic hypertension. Because renal alpha-adrenoceptors are linked to tubular sodium reabsorption, we suggest that an increase in renal alpha 1- (and alpha 2)-adrenoceptors may be a very early step in the development of genetic hypertension.
Michel
M C
MC
Medizinische Klinik and Poliklinik, Division of Renal and Hypertensive Diseases, University of Essen, F.R.G.
Kanczik
R
R
Khamssi
M
M
Knorr
A
A
Siegl
H
H
Beckeringh
J J
JJ
Brodde
O E
OE
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D001835:Body Weight; D003524:Cyclosporins / Q000494:pharmacology; D004195:Disease Models, Animal; D005260:Female; D006973:Hypertension / Q000139:chemically induced / Q000503:physiopathology*; D007668:Kidney / Q000032:analysis*; D008297:Male; D009206:Myocardium / Q000032:analysis*; D009929:Organ Size; D051381:Rats; D011918:Rats, Inbred SHR; D011919:Rats, Inbred Strains; D011942:Receptors, Adrenergic, alpha / Q000032:analysis*; D011943:Receptors, Adrenergic, beta / Q000032:analysis*; D012965:Sodium Chloride
D003524:Cyclosporins; D011942:Receptors, Adrenergic, alpha; D011943:Receptors, Adrenergic, beta; D012965:Sodium Chloride