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.
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.
McLeod
K R
KR
Department of Animal Sciences, University of Kentucky, Lexington 40546-0215, USA.
Bauer
M L
ML
Harmon
D L
DL
Reynolds
C K
CK
Mitchell
G E
GE
D020155:3-Hydroxybutyric Acid; D000641:Ammonia / Q000378:metabolism; D000818:Animals; D002364:Caseins / Q000008:administration & dosage / Q000494:pharmacology*; D003543:Cysteamine / Q000494:pharmacology*; D005947:Glucose / Q000378:metabolism; D006885:Hydroxybutyrates / Q000378:metabolism; D007328:Insulin / Q000378:metabolism; D007773:Lactates / Q000378:metabolism; D008099:Liver / Q000098:blood supply; D008297:Male; D009584:Nitrogen / Q000378:metabolism; D010101:Oxygen Consumption / Q000502:physiology; D011168:Portal System / Q000502:physiology*; D011897:Random Allocation; D012756:Sheep / Q000378:metabolism* / Q000502:physiology; D013004:Somatostatin / Q000494:pharmacology*; D013213:Starch / Q000008:administration & dosage / Q000494:pharmacology*; D014781:Viscera / Q000098:blood supply*
D002364:Caseins; D006885:Hydroxybutyrates; D007328:Insulin; D007773:Lactates; D013004:Somatostatin; D003543:Cysteamine; D000641:Ammonia; D013213:Starch; D005947:Glucose; D009584:Nitrogen; D020155:3-Hydroxybutyric Acid