血管紧张素Ⅱ对大鼠主动脉平滑肌细胞心钠素合成、分泌和基因表达的影响

Effects of angiotensin Ⅱ on synthesis, secretion and gene expression of atrial natriuretic factor in cultured aortic smooth muscle cells from rats

培养的自发性高血压大鼠（ＳＨＲ）及其对照ＷＫＹ大鼠的主动脉平滑肌细胞（ＡＳＭＣ）能合成和分泌心钠素（ＡＮＦ）。ＳＨＲ的ＡＳＭＣ合成和分泌的ＡＮＦ量分别为０．８１±０．０５和０．４０±０．０３ｎｇ／１０６ｃｅｌｌｓ，而ＷＫＹ大鼠为１．００±０．０７和０．７０±０．０３ｎｇ／１０６ｃｅｌｌｓ，前者明显低于后者（Ｐ＜０．０１）。应用ＲＴ－ＰＣＲ方法检出ＡＳＭＣ中存在特异的ＡＮＦｍＲＮＡ．１０－１１～１０－５ｍｏｌ／Ｌ血管紧张素Ⅱ（ＡｎｇⅡ）能明显刺激ＡＮＦ的合成和释放，有量效关系。结果提出：（１）ＡＮＦ可在ＡＳＭＣ中原位合成。（２）ＳＨＲ的ＡＳＭＣ合成和分泌ＡＮＦ量下降及ＡｎｇⅡ刺激下其ＡＮＦｍＲＮＡ表达降低可能在高血压发生的血管机制中起作用。

Abstract The effects of angiotensin Ⅱ (Ang Ⅱ) on the synthesis,secretion and gene expression of atrial natriuretic factor (ANF) were studied in cultured aortic smooth muscle cells (ASMC) from spontaneously hypertensive (SHR) and Wistar Kyoto (WKY) rats. It was found that ANF is present in cultured ASMC and medium from both strains, but the contents in both ASMC and the medium of SHR (0. 81 ±0. 05 and 0. 40±0. 03 ng/10￣6 cells) were lower than those of WKY rats (1. 00±0. 07 and 0. 70± 0. 03 ng/10￣6 cells) (P<0. 01). Incubation of ASMC with 10￣(-11)-10￣(-5)mol/L AngⅡ increased the synthesis and release of ANF in a dose-dependent manner. The effects of AngⅡ± on ANF mRNA expression was also examined by reverse transcription-poly-merase chain reaction (RT-PCR). A 24. 8 % increase of ANF mRNA expression to Ang Ⅱ (10￣(-10)mol/L) was shown in SHR ASMC, while a 41. 4 % increase in WKY rats.These data suggest that (1) ANF is synthesized in ASMC in situ; (2) the decrease of ANF synthesized in and secreted by ASMC from SHR as well as the lower ANF gene expression in response to exogenous Ang Ⅱmay be involved in the vascular mechanism of hypertension.