The action of insulin and dibutyryl cyclic AMP on the biosynthesis of polyunsaturated acids of alpha-linolenic acid family in HTC cells.

Incubation of HTC cells (7288 C) with 114C-alpha-linolenic acid in Swim's 77 medium during 24 hours converted the fatty acid to octadeca-6,9,12,15-tetraenoic acid, eicosa-11,14,17-trienoic acid, eicosa-8,11,14,17-tetraenoic acid, eicosa-5,11,14,17-tetraenoic acid, eicosa-5,8,11,14,17-pentaenoic acid and unsaturated acids of 22 carbons. The existence of two pathways was recognized: one initiated by a delta6-desaturation and the other by an elongation of alpha-linolenic acid. Incubation of the cells with insulin and dibutyryl cyclic AMP modified both pathways in different ways. HTC cells were sensitive to insulin which enhanced the desaturating route increasing eicosapentaenoic acid synthesis and depressed the elongating route decreasing eicosatrienoic acid. In an opposite way, dibutyryl cyclic AMP decreased eicosapentaenoic acid synthesis and increased eicosatrienoic acid.