Effects of Epinephrine and Norepinephrine on the Hepatic Lipids of the Nurse Shark, Ginglymostoma cirratum[*]

Abstract

The lipid and fatty acid composition and the effect of epinephrine and of norepinephrine upon acetate-1-¹⁴C incorporation into liver lipids were studied in the nurse shark. The total lipid content varied between 3.5 and 12.8% of the fresh weight of the organ, an amount significantly lower than that found in the liver of other elasmobranchs. The triglycerides represented about 60% and the phospholipids about 10% of the total extractable lipids, whereas in mammals, these fractions represent 30% and 65% of the total lipid, respectively. Of the total fatty acid content, over 40% was represented by C:20 and C:22 fatty acids; 36% was represented by C:18, C:20 and C:22 polyunsaturated fatty acids. Epinephrine and norepinephrine caused a significant decrease in the total uptake of acetate-1-^l4C in the liver lipids, but their effects on the different lipid fractions were variable. The results are consistent with the notions that liver is an important organ for the storage of fat and that the catecholamines have a lipolytic role in elasmobranch fishes.

Key words

Liver Lipids - Shark - Epinephrine - Norepinephrine - Catecholamines - Lipolysis

1 Aided by Grant AM 06034 from the National Institutes of Health, US Public Health Service.

1 Aided by Grant AM 06034 from the National Institutes of Health, US Public Health Service.

2 Trainee, National Institutes of Health Diabetes Training Program