Smooth Muscle and Molecular Pharmacology Laboratory, Department of Veterinary Pharmacology and Toxicology, College of Veterinary Science and Animal Husbandry, U.P. Pandit Deen Dayal Upadhyaya Pashu Chikitsa Vigyan Vishwavidyalaya Evam Go-Anusandhan Sansthan (DUVASU), Mathura, 281001, India.
Naunyn Schmiedebergs Arch Pharmacol. 2020 Feb;393(2):225-241. doi: 10.1007/s00210-019-01726-y. Epub 2019 Sep 7.
Present study was undertaken to unravel the endothelium-dependent and endothelium-independent relaxant pathways in uterine artery of non-pregnant buffaloes. Isometric tension of arterial rings was recorded using data acquisition system based polyphysiograph. Acetylcholine (ACh) produced endothelium-dependent vasorelaxation by releasing nitric oxide (NO), and inhibition of nitric oxide synthase (NOS) by L-NAME (300 μM) significantly (P < 0.05) reduced the NO release and thereby the vasorelaxant effect of ACh. However, L-NMMA, another NOS inhibitor, and PTIO, a NO scavenger, did not have any additional inhibitory effect on NO and ACh-induced vasorelaxation. Cyclooxygenase (COX) inhibitor (indomethacin) alone did not have any inhibitory action on vasorelaxant response to ACh; however, simultaneous inhibition of COX and NOS enzymes significantly (P < 0.05) attenuated the relaxant response indicating the concurrent release of these two mediators in regulating ACh-induced relaxation. Besides NOS and COX-derived metabolites (EDRF), small (SK) and intermediate (IK) conductance K channels being the members of EDHF play predominant role in mediating ACh-induced vasorelaxation. Using different molecular tools, existence of eNOS, COX-1, andIK in the endothelium, BK in vascular smooth muscle, and SK in both endothelium and vascular smooth muscle was demonstrated in buffalo uterine artery. Gene sequencing of COX-1 and SK genes in uterine artery of buffaloes showed more than 97% structural similarity with ovine (Ovis aries), caprine (Capra hircus), and Indian cow (Bos indicus). Endothelium-independent nitrovasodilator, sodium nitroprusside (SNP), produced vasorelaxation which was sensitive to blockade by soluble guanylate cyclase (sGC) inhibitor (ODQ), thus suggesting the important role of cGMP/PKG pathways in uterine vasorelaxation in buffaloes. Taken together, it is concluded that both endothelium-dependent (EDHF and EDRF) and endothelium-independent (sGC-cGMP) relaxant pathways are present in uterine arteries of non-pregnant buffaloes, and they differently contribute to vasorelaxation during non-pregnant state.
本研究旨在揭示非妊娠水牛子宫动脉中的内皮依赖性和非内皮依赖性舒张途径。使用基于多生理记录仪的数据采集系统记录动脉环的等长张力。乙酰胆碱（ACh）通过释放一氧化氮（NO）产生内皮依赖性血管舒张，而一氧化氮合酶（NOS）抑制剂 L-NAME（300μM）显著（P<0.05）抑制 NO 释放，从而抑制 ACh 的血管舒张作用。然而，另一种 NOS 抑制剂 L-NMMA 和 NO 清除剂 PTIO 对 NO 和 ACh 诱导的血管舒张没有任何额外的抑制作用。单独的环氧化酶（COX）抑制剂（吲哚美辛）对 ACh 引起的血管舒张反应没有任何抑制作用；然而，同时抑制 COX 和 NOS 酶显著（P<0.05）减弱了舒张反应，表明这两种介质的同时释放参与了调节 ACh 诱导的舒张。除了 NOS 和 COX 衍生的代谢物（EDRF）外，小电导（SK）和中间电导（IK）钾通道作为 EDHF 的成员，在介导 ACh 诱导的血管舒张中起主要作用。使用不同的分子工具，在水牛子宫动脉中证明了内皮中的 eNOS、COX-1 和 IK、血管平滑肌中的 BK 以及内皮和血管平滑肌中的 SK 的存在。对水牛子宫动脉中 COX-1 和 SK 基因的基因测序显示，与绵羊（Ovis aries）、山羊（Capra hircus）和印度牛（Bos indicus）的基因具有超过 97%的结构相似性。非内皮依赖性硝基血管扩张剂硝普钠（SNP）引起的血管舒张对可溶性鸟苷酸环化酶（sGC）抑制剂（ODQ）敏感，这表明 cGMP/PKG 途径在水牛子宫血管舒张中起重要作用。综上所述，结论是，非妊娠水牛子宫动脉中存在内皮依赖性（EDHF 和 EDRF）和非内皮依赖性（sGC-cGMP）舒张途径，它们在非妊娠状态下对血管舒张有不同的贡献。
