Changes in the plasma concentration of free fatty acids in rabbits under fatigue-induced stress.

The effect of fatigue-induced stress and of alpha- and beta-adrenoceptor antagonists (phentolamine and propranolol) on plasma free fatty acids (FFA) level was studied in fed and 24 h fasted rabbits. The initial FFA level was significantly higher in the fasted animals than in the fed ones. In the fed control rabbits immediately after stress the FFA level did not change as compared with its initial level. In the fasted control animals directly after stress a marked decrease in the FFA level was observed as compared with its initial value. 15 and 30 min after fatigue-induced stress, both in the fed and fasted control rabbits, a decrease in the FFA level was recorded as compared to that immediately after stress. It was found that propranolol had no significant influence on the FFA level, both in the fed and fasted animals, and phentolamine produced a distinct increase in the FFA level in the fed rabbits only. Immediately after stress the FFA level in the fed propranolol-treated rabbits was unchanged, but in the fed phentolamine-treated animals it was markedly decreased. Directly after stress a decrease of the amount of FFA in the fasted adrenolytic-treated rabbits was recorded, 15 and 30 min after stress the FFA level decreased both in the fed and fasted adrenolytic-treated rabbits. However, this decrease was not as marked as in the fed and fasted control animals. The possible role of lactate and of catecholamines in the changes of plasma FFA concentration was discussed.