title: Ontogeny of renal alpha-1 and alpha-2 adrenoceptors in the spontaneously hypertensive rat.
abstract: Renal alpha-1 and alpha-2 adrenoceptors were characterized during the development of the spontaneously hypertensive rats (SHR) and age-matched Wistar-Kyoto rats through Scatchard analysis of [3H]prazosin and [3H]yohimbine binding to kidney membrane preparations in an attempt to correlate biochemical changes with the reported functional changes occurring in hypertension development in the SHR. Renal alpha-1 and alpha-2 receptor density was higher in SHR than in Wistar-Kyoto rats at all ages tested. In contrast to Wistar-Kyoto rats, in which the number of alpha-1 and alpha-2 receptors remained relatively constant with age, the number of renal alpha-1 adrenoceptors in the SHR was lowest at the 4th week of age (61 fmol/mg) increasing transiently at 5 weeks and then again at 8 week reaching a plateau at that time. The maximum number of binding sites for [3H]yohimbine binding in the SHR was also age dependent. The number of renal alpha-2 adrenoceptors in the SHR was lowest at 4 weeks of age (125 fmol/mg) increasing to 220 fmol/mg at 5 weeks of age and to 260 fmol/mg at 8 weeks of age. Adult levels (308 fmol/mg) were reached by 18 weeks of age. Unlike receptor densities, affinity constants were not significantly altered during postnatal development. The changes in alpha-1 and alpha-2 adrenoceptors in the kidneys of SHR may suggest an important developmental role which is not yet understood.
mesh_terms: D000367:Age Factors; D000818:Animals; D006973:Hypertension / Q000209:etiology* / Q000503:physiopathology; D007668:Kidney / Q000032:analysis*; D007700:Kinetics; D008297:Male; D011224:Prazosin / Q000378:metabolism; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D011942:Receptors, Adrenergic, alpha / Q000032:analysis*; D013564:Sympathetic Nervous System / Q000502:physiology; D014316:Tritium; D014655:Vascular Resistance; D015016:Yohimbine / Q000378:metabolism
chemical_list: D011942:Receptors, Adrenergic, alpha; D014316:Tritium; D015016:Yohimbine; D011224:Prazosin