Location: Forage-animal Production ResearchTitle: Bovine lateral saphenous veins exposed to ergopeptine alkaloids do not relax Author
Submitted to: Joint Meeting of the ADSA, AMSA, ASAS and PSA
Publication Type: Abstract Only
Publication Acceptance Date: 3/8/2013
Publication Date: 7/8/2013
Citation: Klotz, J.L., Pesqueira, A., Branco, A.F., Harmon, D.L. 2013. Bovine lateral saphenous veins exposed to ergopeptine alkaloids do not relax. J. Anim. Sci. Vol. 91, E-Suppl. 2:92. Interpretive Summary:
Technical Abstract: The ergot alkaloid, ergovaline has demonstrated a persistent binding and sustained contractile response in several vascular models. It was hypothesized that different alkaloids isolated from tall fescue (Lolium arundinaceum) will contribute to this response differently. The objective was to compare contractile-response patterns of single additions of 1x10-4M lysergic acid (LSA), lysergol (LYS), ergonovine (ERN), ergotamine (ERT), ergocristine (ERS), ergocryptine (ERP), ergocornine (ERO) and 1x10-6M ergovaline (from a tall fescue seed extract; EXT). Lateral saphenous veins were collected from 6 Holstein steers (397 ± 28 kg) immediately after slaughter, sliced into cross-sections, and suspended in myograph chambers containing oxygenated Krebs-Henseleit buffer (95% O2/5% CO2; pH = 7.4; 37°C). Treatments were added at 0 min and buffer was replaced in 15-min intervals for a 120-min incubation. Time to reach maximum tension and percent relaxation and rate of relaxation were determined following maximum tension for each treatment. Data were normalized to a reference addition of 1x10-4 M norepinephrine and analyzed as a CRD with repeated measures using mixed models of SAS. All compounds tested produced significant contractile responses (P<0.05). Ergoline alkaloids, LSA, LYS, and ERN reached maximum response in less time the remaining compounds (P<0.05) and began to relax immediately with LSA having the greatest percent relaxation (P<0.05). The EXT and ergopeptine alkaloids, ERT, ERS, ERP, and ERO all had slower contractile responses with a longer interval until maximum tension was achieved. Maximal responses to these alkaloids, however, all persisted for the 120-min duration with negligible relaxation occurring. Persistence of contractile response is thought to be the primary contributing factor to vasoconstriction in animals demonstrating signs of fescue toxicosis.