EFFECT OF ARTERIALLY INFUSED CATECHOLAMINES AND INSULIN ON PLASMA-GLUCOSE AND FREE FATTY-ACIDS IN CARP

Common carp (Cyprinus carpio L.), kept at 20 degrees C, were fitted wi th an indwelling PE-50 cannula in the dorsal aorta. Hormones dissolved in Ringer saline were arterially infused at a rate of 1 mu g . kg(-1) . min(-1) for epinephrine (Epi), 2 mu g . kg(-1). min(-1) for norepine phrine (NE), and 1.33 mu g . kg(-1). min(-1) for insulin. Infusion of bovine insulin in carp resulted in a long lasting (24 h) decrease of p lasma free fatty acids (FFA; -0.41 +/- 0.06 mM) and glucose levels (-3 .14 +/- 0.25 mM) compared with preinfusion levels at t = 0. Both Epi a nd NE induced a marked hyperglycemia although Epi was more potent (+8. 2 +/- 0.9 and +6.9 +/- 0.8 mM, respectively). Plasma FFA levels increa sed by 0.25 +/- 0.03 mM compared with preinfusion levels on Epi infusi on. In contrast, during NE infusion, plasma FFA levels decreased signi ficantly by -0.21 +/- 0.03 mM. Plasma insulin titers did not significa ntly change during infusion of NE or Epi. It is concluded that the rat io of NE to Epi is the major factor that determines the effect of cate cholamines on plasma FFA levels in carp. These results may explain spe cies-dependent different effects of hypoxia on FFA metabolism in fish.