| Abstract: | Namdaran, Kiarash, Deanna P. Bracy, D. Brooks Lacy, JaniceL. Johnson, Jennifer L. Bupp, and David H. Wasserman. Gut andliver fat metabolism in depancreatized dogs: effects of exercise andacute insulin infusion. J. Appl.Physiol. 83(4): 1339-1347, 1997. Excessivecirculating fat levels are a defining feature of poor metabolic controlin diabetes. Splanchnic adipose tissue is a source of free fatty acids(FFA), and the liver is a key site of FFA utilization and the solesource of ketones. Despite the role of splanchnic tissues in fatmetabolism, little is known about how these tissues respond to diabetesunder divergent metabolic conditions. Therefore, splanchnic fatmetabolism was studied in poorly controlled diabetes under twoconditions. First, it was studied during exercise, a stimulus thatenhances FFA flux. Second, it was studied while insulin was beingacutely infused to achieve levels normally present during exercise, atreatment that may be expected to inhibit lipolysis. For this purpose,liver and gut arteriovenous differences were used during rest and 2.5 h of treadmill exercise in insulin-deficient(n = 6) and acutely insulin-infused(n = 4) depancreatized (PX) dogs. Thedata show that 1) exercise, ininsulin-deficient PX dogs, leads to an increase in net FFA release frommesenteric fat that is equal in magnitude to the response innondiabetic dogs; 2) net hepaticfractional FFA extraction is increased twofold during exercise in bothinsulin-deficient PX dogs and nondiabetic control dogs;3) during exercise, ~40 and 75%of the FFA consumed by the liver is effectively transferred from fatstores mobilized from splanchnic adipose tissue in insulin-deficient PXand nondiabetic dogs, respectively;4) hepatic ketogenic efficiency iselevated during rest three- to fourfold in insulin-deficient PX dogscompared with nondiabetic control dogs and remains elevated duringexercise; and 5) surprisingly, acuteinsulin replacement is ineffective in normalizing net gut, hepatic, orsplanchnic FFA or ketone body balances in PX dogs. |
