The metabolism of 1-¹⁴C-palmitic acid in the testis of the rat

Abstract

The metabolism of 1-¹⁴C-palmitic acid was studied in rat testis at various intervals after intratesticular injection and after a 2 hr incubation period. Significant catabolism occurred as evidenced by production of¹⁴CO₂ in both in vivo and in vitro experiments. Of the¹⁴C activity retained in the injected testis, less than 15% remained as free fatty acid after 2 hr and less than 5% by the end of 2 weeks. Activity of¹⁴C appeared in phosphatides faster than in the triglyceride fraction, and with time (1–2 weeks) the activity in phosphatides decreased relative to that in triglycerides. In phosphatides of these experiments ca. 80% of the¹⁴C was in the palmitic acid fraction and the balance predominantly (98%) in palmitate with the balance in stearate and oleate. By the first and second weeks almost half of the¹⁴C-palmitate present in the testes had been newly synthesized from¹⁴C-acetyl CoA resulting from oxidation of the administered 1-¹⁴C-palmitate. In the incubated samples the only fatty acid with¹⁴C activity in any lipid fraction was palmitate. In these experiments ca 90% of the¹⁴C was in the free fatty acid fraction, 7% in the phosphatides and 2% in the triglycerides.