Glucose turnover in fast-growing, lean and in slow-growing, obese swine.

Glucose turnover and associated measurements were compared in genetically obese, slow-growing feral pigs (Ossabaw) and domestic lean, fast-growing (Yorkshire) pigs. Five Ossabaw and five Yorkshire pigs 8 wk of age were prepared with indwelling arterial catheters to facilitate injection of tracer and serial sampling of blood. After a 14-h fast, pigs were administered 100 muCi of glucose-6-3H in a single injection; 12 blood samples were obtained over the subsequent 4-h period to obtain tracer dilution curves. Plasma glucose concentrations were the same in both strains (88 mg/100 ml) prior to tracer injection and remained constant for the duration of the 4-h sampling period. Ossabaw pigs exhibited a smaller minimal glucose mass (144 vs 179 mg/kg body weight, P less than .01) and space (16 vs 20%, P less than .01) when compared with Yorkshire pigs. Glucose replacement rate was greater for Ossabaw pigs than for Yorkshire pigs (3.96 vs 2.97 mg.min-1.kg-1 body weight, P less than .001). Minimal transit time was less in Ossabaw pigs than Yorkshire pigs (36 vs 60 min, P less than .001), which reflected the greater rate of irreversible disposal of tracer from the glucose pool of Ossabaw pigs. In conclusion, under these experimental conditions and at similar fasting glucose concentrations, glucose turnover and metabolic clearance rates were greater in Ossabaw than Yorkshire pigs. The results suggest a greater rate of fasting liver gluconeogenesis during short-term fasting in the young Ossabaw than the Yorkshire pig.