Glycemic and glycosuric responses in white sturgeon (Acipenser transmontanus) after oral administration of simple and complex carbohydrates

The ability of white sturgeon to utilize different carbohydrates was studie d by using a technique combining esophageal intubation, dorsal aorta cannul ation, and urinary catheterization. Seven groups of five fish each were int ubated with 1 g kg(-1) body weight of gelatin (sham), glucose, maltose, cor n dextrin, potato dextrin, raw corn starch, or raw potato starch 48 h post- operation. The observed plasma glucose concentrations peaked at 6 h post-in tubation of different carbohydrates and was the highest (10.2 +/- 0.5 mmol l(-1), mean +/- SEM, n = 5) in the glucose group. The glycemic index, which was measured for the first time in fish, was higher (P < 0.05) in the gluc ose group than in all other groups except for the maltose group. Urinary gl ucose excretion accounted for less than 1% of the total intubated dosage an d it was significantly higher in the glucose group (5.16 +/- 1.25 mg kg(-1) 24 h(-1)) than in the sham (0.41 +/- 0.32 mg kg(-1) 24 h(-1)) and potato s tarch groups (0.31 +/- 0.23 mg kg(-1) 24 h(-1)). The first order kinetic fu nction showed that complex carbohydrates delayed plasma glucose concentrati ons peak time and prolonged glucose efflux but did not affect glucose influ x rate. The higher glucose efflux rate helped to alleviate the hyperglycemi a in the glucose group. The present technique overcame some limitations of the previous oral challenge test and provided a more accurate description o f carbohydrate utilization by white sturgeon. Glycemic index appeared to be a sensitive index to complement apparent digestibility coefficient determi nation and growth trials in evaluating carbohydrate utilization by white st urgeon. (C) 2001 Elsevier Science B.V. All rights reserved.