Afiatpour Parviz, Latifpour Jamshid, Takahashi Wataru, Yono Makoto, Foster Harris E, Ikeda Kazuyoshi, Pouresmail Mehdi, Weiss Robert M
Section of Urology, Yale University School of Medicine, P.O. Box 208041, New Haven, CT 06520-8041, USA.
Naunyn Schmiedebergs Arch Pharmacol. 2003 May;367(5):462-72. doi: 10.1007/s00210-003-0715-6. Epub 2003 Apr 17.
The effect of aging on functional, biochemical, anatomical and molecular properties of endothelin (ET) receptors in bladder smooth muscle of the 3-week-, 3-month- and 22-month-old rats was examined using isolated muscle bath techniques, radioligand binding on membrane particulates and slide mounted tissue sections, and real-time reverse transcription polymerase chain reaction (RT-PCR). ET-1 induced significantly larger contractile responses in bladder dome muscle strips from 3-week- than from 3-month- and 22-month-old rats. The expression level of total ET receptors, determined by saturation binding experiments with [(125)I]ET-1, was higher in detrusor from 3-week- than 22-month-old rats. Inhibition studies with BQ123, a selective ET(A) receptor antagonist, indicated the predominance of the ET(A) receptor subtype and a similar proportion of ET(A) to ET(B) receptor subtypes in the rat detrusor at all ages studied. Autoradiographic data support the age-dependent decrease in the density of ET receptors and also indicate that the ET(A) receptor subtype is primarily located in the smooth muscle layer, whereas the ET(B) receptor subtype is located in both the urothelial and smooth muscle layers. Determined by real-time RT-PCR, ET 1, ET-3, ECE-1 and ET receptor subtype (ET(A) and ET(B)) mRNAs were shown to be higher in bladders of 3-week- compared to 3-month- or 22-month-old rats. This study indicates age-dependent alterations in the ET receptor system at both gene transcript and protein levels in the Fischer rat detrusor.
采用离体肌槽技术、膜微粒的放射性配体结合及载玻片固定组织切片技术，以及实时逆转录聚合酶链反应（RT-PCR），研究了衰老对3周龄、3月龄和22月龄大鼠膀胱平滑肌中内皮素（ET）受体的功能、生化、解剖学及分子特性的影响。ET-1诱导3周龄大鼠膀胱顶部肌条产生的收缩反应显著大于3月龄和22月龄大鼠。通过用[（125）I]ET-1进行饱和结合实验测定，3周龄大鼠逼尿肌中总ET受体的表达水平高于22月龄大鼠。用选择性ET(A)受体拮抗剂BQ123进行的抑制研究表明，在所有研究年龄的大鼠逼尿肌中，ET(A)受体亚型占主导地位，且ET(A)与ET(B)受体亚型的比例相似。放射自显影数据支持ET受体密度随年龄下降，且表明ET(A)受体亚型主要位于平滑肌层，而ET(B)受体亚型位于尿路上皮和平滑肌层。通过实时RT-PCR测定，与3月龄或22月龄大鼠相比，3周龄大鼠膀胱中ET-1、ET-3、ECE-1和ET受体亚型（ET(A)和ET(B)）的mRNA水平更高。本研究表明，Fischer大鼠逼尿肌中ET受体系统在基因转录和蛋白质水平上均存在年龄依赖性改变。
