Year: 2018
Type: dissertation
Abstract: A limited number of ß-adrenergic agonists (ß-AA) are currently used for\nredirecting dietary energy from adipose tissue accretion towards muscle growth. At the\nend of typical feedlot finishing, cattle have depressed insulin sensitivity, similar to type\nII diabetes in humans. The objective of this study was to compare the effects of a known\nβv3-AA (BRL 37344) to a novel ß-AA (Experior) on muscle metabolism in vitro. We\nhypothesized that Experior would attenuate insulin insensitivity by promoting glucose\nmetabolism in muscle. The M. longissimus lumborum (LL) was removed from the 9th to\n11th rib from four steers. From the LL samples, muscle strips were dissected parallel to\nmuscle fiber orientation. The conversion of glucose to glycogen, COv2, and lactate was\ntested in muscle strips incubated for 90 min with 50 μM Experior, 50 μM BRL 37344,\nor no β-AA (Control), and different insulin concentrations. Incubation time was\nestablished by a preliminary experiment that determined the effect of different\nincubation times (30 min, 60 min, 90 min) on glycogen, COv2, and lactate production.\nThere were no (P > 0.05) insulin concentration x treatment effects, insulin concentration\neffects, and no significant effect of treatment on lactate production. There was a\nsignificant treatment effect of conversion of glucose to glycogen (P < 0.001) and COv2 (P\n= 0.018). BRL 37344 caused 62% lower glycogen production compared to Control\nsamples, and 50% lower glycogen production compared to Experior samples. Control\nsamples produced 4.3 nmol/100 mg·90 min, Experior samples produced 3.1 nmol/100\nmg·90 min glycogen, while BRL 37344 samples produced 1.6 nmol/100 mg·90 min.\nBRL 37344 elicited 23% more COv2 than Experior, and 41% more COv2 than Control\nsamples. Control samples produced 171.3 nmol/100 mg·90 min COv2, Experior samples\nproduced 222.9 nmol/100 mg·90 min COv2, while BRL 37344 samples produced 292.6\nnmol/100 mg·90 min COv2. Experior did not have a consistent effect on glycogen or COv2\nproduction. We discovered the presence of ßv3- AR in muscle, since there was a distinct\nresponse of the muscle strips to BRL 37344. The relative insensitivity of bovine muscle\nto insulin is consistent with insulin resistance observed in feedlot cattle.
Author: Jillian Taylor Jobe
Language: English
Subfield: Animal Science and Zoology
Domain: Life Sciences
Open Access status: green
Funder: Elanco Animal Health
OpenAlex ID: W3202724292