Increased density of (3H)-yohimbine binding sites in spontaneously hypertensive rat mesenteric artery.
Specific binding of (3H)-prazosin and (3H)-yohimbine to plasma membrane vesicles of mesenteric arteries from SHR and WKY rats at 16-18 weeks was compared. The radioligand binding was carried out in Mg-MOPS buffer at 25 degrees C for 25 min. There was no change in the density or the affinity of (3H)-prazosin binding in SHR vessels (Bmax 188 +/- 33 fM/mg protein, Kd 1.26 nM) compared with WKY (Bmax 211 +/- 28 fM/mg protein, kd 1.24 nM). However, the Bmax of (3H)-yohimbine binding was moderately, but significantly, increased in SHR arteries (Bmax 323 +/- 22 fM/mg protein) compared with WKY (Bmax 252 +/- 17 fM/mg protein) without any change in the sensitivity (Kd 26 nM versus 25.9 nM). These results suggest that postsynaptic alpha 2-adrenoceptors density is increased in hypertensive rat mesenteric arteries. The role of this increased number of receptors in the pathogenesis of hypertension is not known.
D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D008297:Male; D008638:Mesenteric Arteries / Q000032:analysis* / Q000378:metabolism; D011224:Prazosin / Q000378:metabolism; D011869:Radioligand Assay; D051381:Rats; D011918:Rats, Inbred SHR / Q000378:metabolism*; D011919:Rats, Inbred Strains / Q000378:metabolism*; D011921:Rats, Inbred WKY; D011942:Receptors, Adrenergic, alpha / Q000032:analysis* / Q000378:metabolism; D014316:Tritium; D015016:Yohimbine / Q000378:metabolism*
D011942:Receptors, Adrenergic, alpha; D014316:Tritium; D015016:Yohimbine; D011224:Prazosin