| 15569273 |
Luo G, Xu CB, Cao YX, Edvinsson L: Transcriptional up-regulation in expression of 5-hydroxytryptamine2A and transcriptional down-regulation of angiotensin II type 1 receptors during organ culture of rat mesenteric artery. Basic Clin Pharmacol Toxicol. 2004 Dec;95(6):280-7.
The purpose of this study was to investigate in rat mesenteric artery if there is up-regulation of 5-hydroxytryptamine (5-HT) receptors and angiotensin II receptors and the potential role of protein kinase C activation in the smooth muscle cells during organ culture. Angiotensin II, 5-HT and potassium induced contraction of ring segments without endothelium, monitored by a sensitive in vitro pharmacology method. After the culture of the arterial ring segments for 24 hr, the concentration-contraction curves induced by 5-HT slightly shifted towards to the left with pEC (50) from 6.64+/-0.11 to 6.84+/-0.11 and a significant increase in E (max) from 147+/-11% to 246+/-15% (P <0.05), compared with that obtained in fresh segments. In contrast, the angiotensin II concentration-contraction curve only showed a significant decrease in E (max) from 99+/-10% to 37+/-8%. Specific antagonists for the 5-HT type 2A receptors (5-HT (2A)) and angiotensin II type 1 receptors (AT (1)) demonstrated that the contractions occurred via 5-HT (2A) and AT (1) receptors, respectively. Real-time PCR revealed that the 5-HT (2A) receptor mRNA was up-regulated in parallel with the contractile response while there was a down-regulation of AT (1) receptor mRNA. Transcriptional inhibitor actinomycin D and specific protein kinase C inhibitor Ro31-8220 demonstrated that it was a transcriptional mechanism with involvement of protein kinase C that regulated the enhanced expression of 5-HT (2A) receptors in the mesenteric artery. |
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