The mode of action of hepatic nerves on the metabolism of carbohydrates was studied in the rat liver perfusedin sifu.
- 1Electrical stimulation of the nerve bundles around the hepatic artery and the portal vein resulted in an increase of glucose and lactate output, an enhancement of phosphorylase a activity and a decrease of portal flow.
- 2Sodium nitroprusside prevented the hemodynamic changes after nerve stimulation without affecting the metabolic alterations.
- 3Phentolamine or an extracellular calcium level below 300 μmol × 1−1 abolished both hernodynamic and metabolic changes after nerve stimulation, while propranolol or atropine were without effect.
- 4Norepinephrine infusion mimicked nerve stimulation only at the highly unphysiological concentration of 0.1 μM; it was not effective at a concentration of 0.01 μM, which might be reached in the sinusoidal blood due to an overflow from intrahepatic synapses.The present results suggest that, in rat liver, glycogen breakdown is regulated by α-sympathetic nerves directly rather than indirectly via hemodynamic changes or via norepinephrine overflow.
Hexokinase (EC 22.214.171.124)
glucose-6-phosphate dehydrogenase (EC 126.96.36.199)
lactate dehydrogenase (EC 1 .1.1 .27)
glycogenphosphorylase (EC 188.8.131.52)
3′:5′-cyclic-AMP phosphodiesterase (EC184.108.40.206)
6-phosphofructokinase (EC 220.127.116.11)