Proximal tubular alpha 2-adrenoceptor density in the spontaneously hypertensive rat.
In the kidney of the spontaneously hypertensive rat (SHR), alpha 2-adrenoceptors are increased and may be related to hypertension. We measured alpha 2-adrenoceptor density and characteristics in a proximal tubule suspension with the alpha 2-adrenoceptor antagonist, 3H-rauwolscine. SHR had a significantly greater density of alpha 2-adrenoceptors when compared to their normotensive controls, the Wistar-Kyoto (WKY) rats (146 +/- 13 v 58 +/- 7 fmol/mg protein; P less than .001). Competition experiments determined the alpha 2-adrenoceptor to be an alpha 2B-subtype. Agonist competition curves were shallow and exhibited pseudo-Hill slopes of less than 1, indicating that they bind to both high and low affinity receptor sites. In summary, alpha 2-adrenoceptors are increased in the proximal tubule of SHR and appear to be of the alpha 2B-subtype. An increase in alpha 2-adrenoceptors may be related to abnormalities in hypertension.
Stanko
C K
CK
Department of Pharmacology & Therapeutics, University of Manitoba, Winnipeg, Canada.
Smyth
D D
DD
D000818:Animals; D006973:Hypertension / Q000378:metabolism*; D007687:Kidney Tubules, Proximal / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D011869:Radioligand Assay; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D011942:Receptors, Adrenergic, alpha / Q000378:metabolism*
D011942:Receptors, Adrenergic, alpha