Endothelium -Dependent and Endothelium -Independent Relaxant Pathways in Uterine Artery of Buffaloes (Bubalus Bubalis)
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Date
2018-06-06
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U.P. Pandit Deen Dayal Upadhyaya Pashu-Chikitsa Vigyan Vishwavidyalaya Evam Go Anusandhan Sansthan, (DUVASU), Mathura – 281001
Abstract
Present study was undertaken to unravel the endothelium-dependent and endotheliumindependent relaxant pathways in uterine artery of buffaloes collected from local abattoir and mounted in organ bath in MKHS maintained at 37 ± 0.5 oC. Micrometrical measurements show that width of tunica interna, lumen and arterial diameter increased while width of tunica media decreased during pregnancy along with increase in the width of tunica externa and arterial wall thickness during early pregnancy and decrease during mid pregnancy as compared to non-pregnancy state. Following an equilibration period of about 1 hr, uterine arterial rings were pre-contacted with 60 mM KDS and thereafter pre-contracted with endothelin 1 to induce vasoconstriction. Endothelium intactness was ascertained by ACh-induced vaso-relaxation. Uterine artery collected from the animals in late phase of di-estrus with straight and smooth blood vessels responded best. Passive tension and pre-contractile agonist’s studies revealed that, endothelin 1 was the best precontractile agent and 2 g passive tension was optimum for uterine arterial rings in MKHS. Uterine artery of the early pregnancy stage buffaloes was most sensitive to endothelin 1. Uterine arterial rings of non-pregnant buffaloes exhibited significantly higher basal tension or tonicity and archived lower maximal tension to 60 mM KDS than the uterine artery of pregnant buffaloes. Acetylcholine-induced relaxation in uterine artery of buffaloes was endothelium-dependent in both non-pregnant and pregnant buffaloes. Non-pregnant buffaloes uterine artery was most sensitive to vaso-relaxant effect of ACh. L-NAME at 300 µM, but not at 100 µM, blocked the release of NO in uterine artery of non-pregnant buffaloes. Both L-NMMA (100 µM) and PTIO (100 µM) failed to block ACh-induced vasorelaxation in non-pregnant buffalo uterine artery. Indomethacin (10 µM) alone failed to block ACh-induced vasorelaxation but when use in combination with L-NAME at 100 µM and 300 µM caused significant inhibition of ACh-induced relaxation in nonpregnant buffaloes uterine artery. ACh-induced relaxation in non-pregnant buffaloes uterine artery was significantly reduced in the presence of 60 mM KDS and it was decreased as the pregnancy advanced. Both Tram 34 (1 µM) and apamin (100 nM), alone and in combination, significantly reduced the AChinduced relaxation in non-pregnant buffalo uterine artery. Indomethacin (10 µM) alone and in combination with L-NAME (100 µM) resulted in significant rightward shift of the DRC of ACh with significant attenuation in pD2 value of ACh while L-NAME (100 µM) alone failed to significantly reduce ACh-induced relaxation in early-pregnancy stage uterine artery. In the presence of L-NAME (100 µM) and indomethacin (10 µM) respectively, the DRC of ACh was significantly shifted towards right and left with significant reduction and potentiation of the maximal responses respectively, while in the combined presence of L-NAME (100 µM) and indomethacin (10 µM) the DRC was superimposed over the DRC of ACh in uterine artery of mid-pregnancy stage buffaloes. SNP caused dose-dependent relaxation in buffalo uterine artery, and the DRC of SNP was significantly shifted towards left with significant increase in potency during pregnancy. In the presence of ODQ, the DRC of SNP was significantly shifted towards right with significant reduction in the potency without much change in the maximal relaxation. Amongst the different antagonists used, only combination of LNAME (100 µM/300 µM) and indomethacin (10 µM) cause marked increase in basal tone of nonpregnant buffalo uterine artery. PCR, western blot and immunohistochemistery studies revealed the presence of eNOS, COX-1, and IKCa in the endothelium, BKCa in the smooth muscle and SKCa in both the endothelium and smooth muscle of buffalo uterine artery and their expression is differently regulated during pregnancy. Gene sequencing of eNOS, COX1 and SKCa genes in uterine artery of buffaloes showed more than 93% structural similarity with ovine (Ovis aries), caprine (Capra hircus) and Indian cow (Bos indicus). From the results of present study, it is conclude that both endotheliumdependent (EDHF and EDRF) and endothelium-independent (sGC-cGMP) relaxant pathways are present in buffalo uterine artery and they differently contribute to vasorelaxation during non-pregnant and pregnancy states.
Description
Endothelium -Dependent and Endothelium -Independent Relaxant Pathways in Uterine Artery of Buffaloes (Bubalus Bubalis)
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