Vanscheeuwijck P, Van de Velde E, Fraeyman N
Heymans Institute of Pharmacology, University of Ghent Medical School, Belgium.
Eur J Pharmacol. 1989 Oct 17;172(4-5):373-80. doi: 10.1016/0922-4106(89)90018-7.
beta-Adrenoceptor density and ligand affinity, basal adenylate cyclase activity and cAMP synthesis upon stimulation with forskolin, fluoride, guanine nucleotides (GTP or guanylyl imidodiphosphate (GppNHp) or isoproterenol in the presence of the nucleotides were studied in membranes prepared from lungs of young (aged 2-3 months) and of old (aged 24-25 months) male Wistar rats. There was a significant (P less than 0.05, 21%) increase in beta-receptor density and a significant (P less than 0.05, 38%) decrease in the percentage of high-affinity binding sites for isoproterenol. Both basal adenylate cyclase activity and that after stimulation with guanine nucleotides or isoproterenol in the presence of nucleotides were unaltered with age. Forskolin stimulation of cAMP synthesis was significantly reduced (by 24%, P less than 0.05) in tissues from older animals. It is suggested that the age-dependent changes in properties of beta-receptors in rat lungs are compensatory, in order to ensure equal cAMP production for equal agonist stimulation.
在从年轻（2 - 3个月龄）和老年（24 - 25个月龄）雄性Wistar大鼠肺组织制备的膜中，研究了β - 肾上腺素能受体密度和配体亲和力、基础腺苷酸环化酶活性以及在用福斯高林、氟化物、鸟嘌呤核苷酸（GTP或鸟苷酰亚胺二磷酸（GppNHp））刺激时或在核苷酸存在下用异丙肾上腺素刺激时的cAMP合成。β - 受体密度显著增加（P < 0.05，21%），而异丙肾上腺素高亲和力结合位点的百分比显著降低（P < 0.05，38%）。基础腺苷酸环化酶活性以及在核苷酸存在下用鸟嘌呤核苷酸或异丙肾上腺素刺激后的活性均不随年龄变化。老年动物组织中福斯高林刺激的cAMP合成显著降低（降低24%，P < 0.05）。有人提出，大鼠肺中β - 受体特性的年龄依赖性变化是一种代偿，以确保在同等激动剂刺激下产生等量的cAMP。
