Substrate oxidation by isolated ovine enterocytes is increased by phlorizin-induced glucosuria

Abstract

. 2001. Substrate oxidation by isolated ovine enterocytes is increased by phlorizin-induced glucosuria. Can. J. Anim. Sci. 81: 585-588. Intestinal cells harvested from wethers injected with phlorizin were utilized to determine the effects of decreased glucose availability on glucose, glutamine, and butyrate oxidation by ovine intestinal cells. Phlorizin injection increased (P = 0.002) conversion of substrates to CO 2 by isolated enterocytes but not by colonocytes (P = 0.098).Key words: Enterocytes, colonocytes, ruminant, glucose Beaulieu, A. D., Overton, T. R. et Drackley, J. K. 2001. La glycosurie induite par la phlorizine accroît l'oxydation des substrats par les entérocytes isolés des ovins. Can. J. Anim. Sci. 81: 585-588. Les cellules intestinales prélevées chez des béliers castrés à qui on avait inoculé de la phlorizine ont servi à déterminer les effets d'une baisse de la quantité disponible de glucose sur l'oxydation du glucose, de la glutamine et du butyrate dans les cellules intestinales des ovins. L'injection de phlorizine accroît (P = 0,002) la conversion des substrats en CO 2 par les entérocytes mais pas par les colonocytes (P = 0,098). Mots clés: Entérocytes, colonocytes, ruminants, glucoseHigh-producing dairy cows experience an immediate and dramatic increase in demand for glucose at the onset of lactation. The mammary gland requires 60-85% of total glucose used by the body, and glucose supply to the mammary gland is a major determinant of milk yield (reviewed by Reynolds et al. 1994). Glucose needs are met via hepatic gluconeogenesis (Huntington 1990) as net absorption of glucose from the portal-drained viscera provides minimal or no (Reynolds et al. 1994) glucose supply to peripheral tissues.The portal-drained viscera influence the supply of nutrients to the liver and mammary gland. Moreover, the gut accounts for a disproportionately high rate of O 2 consumption relative to its mass (Huntington 1990). Enterocytes isolated from the jejunum of rats utilized glutamine and glucose at comparable rates for oxidative metabolism (Fleming et al. 1997). Limited evidence, however, suggests that glucose is quantitatively more important than glutamine as an energy source for enterocytes from lactating cows (Okine et al. 1995). Few data are available on patterns of substrate use by ruminant colonocytes.Phlorizin, a plant glycoside, is a competitive inhibitor of Na + -dependent glucose transport and prevents the reabsorption of glucose in the renal tubules and small intestine (reviewed by Amaral-Phillips et al. 1993). Phlorizininduced glucosuria in growing wethers has been used as a model to examine hepatic adaptations to increased glucose demand in ruminants (Overton et al. 1998). Phlorizin injections decreased concentrations of glucose and insulin in plasma from lactating cows (Amaral-Phillips et al. 1993). Consistent with metabolic adaptations to an increased glucose demand, phlorizin injection did not affect daily dry matter intake, milk production, or milk composition in dairy cows (Amaral-Phillips et al. 1...

Supplementation of 1% l-Glutamine to Milk Replacer Does Not Overcome the Growth Depression in Calves Caused by Soy Protein Concentrate

“…Glutamine (Gln) is a major fuel for intestinal enterocytes in mammals (Reeds and Burrin, 2001), including ruminants such as cattle (Okine et al, 1995) and sheep (Beaulieu et al, 2001), and is involved in maintenance of intestinal mucosal integrity (Potsic et al, 2002). The unique roles of Gln have stimulated interest in its potential ability to modulate intestinal injury, promote healing, or lessen the impact of diarrhea (Reeds and Burrin, 2001).…”