Distribution and aging changes of αィイD21ィエD2-adrenoceptor subtype mRNA in human renal artery.

This study was intended to quantify the amounts of the α D21 -adrenoceptor subtype mRNAs inhuman renal artery，and demonstrate the distribution of receptor subtype responsible for the contraction of renalartery. RNase protection assay showed that the mean amount of α D21a - mrna was much more thanthat of α D21b D2- or α D21d D2- mrnas in both the main and branch renal arteries. However，the abundance of α D21a D2-mRNA in human renal artery was much less than our previous data in theprostate. By in situ hybridizationall α - D21 - D2 subtype mRNAs were localized in the smooth muscle cells of the tunica media of theartery,and the distribution pattern of these three mRNAs in the main artery was the same as in the branchartery . however,the intensity of signals for α - D21d - 2 and α - D21b - 2 antisense RNAs probes were than thatfor α - D21a - D2 antisense RNA probe. In the functional study，concentration-response curves to noradrenaline pretreated with KMD-3213，an α - D21A/L -adrenoceptor selective antagonist，seemed to be biphasic curves. Chloroethyclonidine failed to inactivate thenoradrenaline-induced contraction and prazosin showed relatively low affinity with a pA - 22 - D2value of 8.8. These data suggest that the α - D21A/L -adrenoceptor primarily mediates thoseresponses to noradrenaline in this artery. The other α D21 -adrenoceptor subtypes could alsomediate the secondary contractile response to noradrenaline in this artery。

This study was intended to quantify the amounts of the αィイD21ィエD2-adrenoceptor subtype mRNAs in human renal artery, and demonstrate the distribution of receptor subtype responsible for the contraction of renal artery. RNase protection assay showed that the mean amount of αィイD21aィエD2-mRNA was much more than that of αィイD21bィエD2- or αィイD21dィエD2-mRNAs in both the main and branch renal arteries. However, the abundance of αィイD21aィエD2-mRNA in human renal artery was much less than our previous data in the prostate. By in situ hybridization, all αィイD21ィエD2 subtype mRNAs were localized in the smooth muscle cells of the tunica media of the artery, and the distribution pattern of these three mRNAs in the main artery was the same as in the branch artery. However, the intensity of signals for αィイD21dィエD2 and αィイD21bィエD2 antisense RNAs probes were lower than that for αィイD21aィエD2 antisense RNA probe. In the functional study, concentration-response curves to noradrenaline pretreated with KMD-3213, an αィイD21A/LィエD2-adrenoceptor selective antagonist, seemed to be biphasic curves. Chloroethyclonidine (CEC) failed to inactivate the noradrenaline-induced contraction and prazosin showed relatively low affinity with a pAィイD22ィエD2 value of 8.8. These data suggest that the αィイD21A/LィエD2-adrenoceptor primarily mediates those responses to noradrenaline in this artery. The other αィイD21ィエD2-adrenoceptor subtypes could also mediate the secondary contractile response to noradrenaline in this artery.