Journal of Animal Science, Vol 75, Issue 11 3026-3037, Copyright © 1997 by American Society of Animal Science

JOURNAL ARTICLE

Effects of exogenous somatostatin and cysteamine on net nutrient flux across the portal-drained viscera and liver of sheep during intraduodenal infusion of starch hydrolysate and casein

K. R. McLeod, M. L. Bauer, D. L. Harmon, C. K. Reynolds and G. E. Mitchell Jr
Department of Animal Sciences, University of Kentucky, Lexington 40546-0215, USA.

We used eight Polypay wethers (36 +/- .6 kg BW) fitted with hepatic portal, hepatic venous, mesenteric arterial and venous, and duodenal catheters in a crossover design experiment to determine the influence of somatostatin (SRIF) on splanchnic metabolism. Each crossover period consisted of 14 d, with net flux of nutrients and hormones (venoarterial differences x blood flow) measured on d 14. Before flux measurements, wethers received an i.v. dose (0 h) of either 0 (vehicle) or 50 mg x kg BW(-1) x 10 min(-1) cysteamine (CSH, SRIF-depleting agent) followed by a continuous duodenal infusion (h 10 to 22) of a starch hydrolysate-casein solution. Six sets of arterial, portal, and hepatic blood samples were obtained (h 12 to 16), after which a primed (10 microg), continuous jugular infusion of SRIF-14 (5.0 microg x kg BW(-1) x h(-1)) was initiated and sampling protocol repeated (h 18 to 22). Cysteamine administration increased (P < .01, vs control) portal and hepatic blood flow in the absence of exogenous SRIF (CSH x SRIF, P < .01). Net portal-drained viscera (PDV) release of glucose, alpha-amino N, ammonia N, beta-hydroxybutyrate, and oxygen consumption were decreased (P < or = .10) and lactate release increased (P = .005) during SRIF infusion. The CSH increased (P < .05) PDV release of beta-hydroxybutyrate and insulin and increased (P = .09, CSH alone vs control) net release of glucose in the absence of exogenous SRIF. Exogenous SRIF increased (P = .10) and CSH decreased (P = .09) net hepatic glucose output, whereas liver oxygen consumption was decreased (P = .04) with exogenous SRIF and increased (P = .01) with CSH. Net total splanchnic alpha-amino N release and oxygen consumption were decreased (P < .10) with exogenous SRIF, but CSH increased (P < .05) insulin release and oxygen consumption. These data provide initial evidence for a regulatory involvement of SRIF in visceral metabolism in ruminants.

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