Tissue and organ distribution of14C-activity in dextrin-adapted Atlantic salmon after oral administration of radiolabelled14C1-glucose

Abstract

Accumulation of 14C in various tissues and organs was studied in three different groups of 0.8-kg Atlantic salmon Salmo salar force-fed with 14C1-glucose in order to evaluate if metabolism of glucose depended on adaptation to dietary carbohydrate level. The salmon had been fed diets supplemented with 0, 100 and 200 g maize dextrin kg−1 for 10 months before the experiment. The fish were force-fed 6.65 × 104 Bq of 14C1 glucose kg−1 BW, in gelatin capsules. Fish for analysis were obtained 16 h later. 14C was measured in blood plasma, gill, kidney, liver and white muscle, and in lipid extract of liver. The liver contained most 14C, followed by heart, blood plasma, gill and liver lipid extract, while kidney and muscle contained the least 14C per gram or millilitre tissue. The muscle contained most radioactivity, on an estimated total tissue basis, followed by liver, blood plasma, gill, liver lipid extract, kidney and heart tissue. Thirty-eight per cent of the orally administered 14C was recovered in the salmon adapted to the diet without dextrin after 16 h. This was significantly (P < 0.05) higher than the 30% and 32% recovered in the salmon adapted to diets with 10% and 20% dextrin. This effect on adaptation to dietary dextrin level in glucose uptake or metabolism was supported by a trend (P < 0.10) toward higher radioactivity per gram or millilitre of each individual tissue in the fish adapted to the diet without dextrin, when compared with the other two adaptation regimes.