Our objectives were to test whether or not prostaglandin E 2 (PGE 2 ) relaxes equine isthmic circular smooth muscle in vitro, and to determine the effects of surgery, time postexcision, and source of tissue on isthmic responsiveness to PGE 2 . Oviducts were surgically collected after general anesthesia from four research herd mares on Day 5 postovulation, after stunning and exsanguination from four research herd mares on Day 5, and from seven slaughterhouse mares during diestrus. Circular smooth muscle contractions were measured in vitro with an isometric force transducer. Tissues were precontracted with 2 |iM histamine and then were treated with PGE 2 (0, 0.1, 1, 10, 100, or 1000 nM). Histamine treatment significantly (p < 0.001) increased tissue tension (500.0 ± 0.0 to 818.9 ± 47.9 mg) and contractile frequency (13.3 ± 0.4 to 29.8 ± 1.6 contractions/min), and decreased contractile amplitude (69.7 ± 11.9 to 23.7 ± 4.2 mg). PGE 2 treatment significantly (p < 0.001) decreased tissue tension and contractile frequency and significantly (p < 0.001) increased contractile amplitude of histamine-precontracted tissue in a dose-dependent manner. Tissue obtained from mares anesthetized on Day 5 was significantly (p < 0.05) less responsive to PGE 2 than tissue obtained from mares killed on Day 5. Responsiveness to PGE 2 of tissue from mares killed on Day 5 did not decrease significantly after 12 h of storage at 4°C. These results support the hypothesis that PGE 2 relaxes isthmic circular smooth muscle, and indicate that anesthetic agents reduce isthmic responsiveness to PGE 2 .
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.