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Diarrhea reduces the rates of cardiac protein synthesis in myofibrillar protein fractions in rats in vivo

Hunter, Ross V. and Patel, Vinood B. and Miell, John and Wong, H. John and Marway, Jaspaul and Richardson, Peter and Preedy, Victor R. (2001) Diarrhea reduces the rates of cardiac protein synthesis in myofibrillar protein fractions in rats in vivo. Journal of Nutrition, 131 (5). pp. 1513-1519. ISSN 0022-3166

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Official URL: http://jn.nutrition.org/cgi/content/full/131/5/151...

Abstract

Although chronic diarrhea affects heart function and morphology, the pathogenic mechanisms are unknown. It was our hypothesis that diarrhea imposes metabolic stress to inhibit the synthesis of new contractile proteins. To test this hypothesis, we investigated the effects of lactose-induced diarrhea in rats. The groups were: 1) freely fed controls, 2) rats with lactose-induced diarrhea or 3) pair-fed rats. After 1 wk, hearts from the rats were subjected to subcellular fractionation techniques to isolate the major protein fractions, including myofibrillar proteins. The rates of protein synthesis were measured with concomitant assay of cardiac composition and plasma analytes. In comparison with the control group, diarrhea induced the following changes (P < 0.05): a decrease in heart weight, reduced RNA and mixed protein contents and a reduction in the fractional rate of mixed protein synthesis. There was a reduction in the content of all protein fractions. The fractional synthesis rate was reduced only for the myofibrillar fraction. Plasma insulin-like growth factor-I, but not corticosterone, was reduced. Plasma cholesterol and triglyceride concentrations were also reduced. In comparison with the pair-fed group, diarrhea induced the following changes (P < 0.05): a reduction in heart weight and fractional rate of mixed protein synthesis, reduced myofibrillar absolute synthesis rate and increased sarcoplasmic/myofibrillar fractional synthesis rate ratio. Plasma bicarbonate, triglyceride and urea concentrations were reduced, with an increase in albumin. Diarrhea impaired cardiac biochemistry, including a reduction in protein content and synthesis. A substantial proportion of these changes is due to anorexia, but the selective reduction in the synthesis of contractile proteins is a feature exclusive to the diarrhea group and may be due to reductions in plasma insulin-like growth factor-I.

Item Type:Article
Additional Information:Online ISSN 1541-6100
Uncontrolled Keywords:Diarrhea, heart, protein synthesis, rats, insulin-like growth factor
Research Community:University of Westminster > Life Sciences, School of
ID Code:411
Deposited On:17 Aug 2005
Last Modified:07 Jun 2010 12:47

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