Hepatic denervation alters hemodynamic response to hemorrhage in conscious rats

We investigated the effect of liver denervation on cardiovascular homeostasis. Three days after surgical denervation of the liver, hemodynamic studies (radioactive microsphere method) were conducted in conscious rats. The efficacity of the liver denervation procedure was confirmed by a significant decrease in norepinephrine content in various lobes of the liver. Liver denervation did not affect either systemic or splanchnic resting hemodynamics. However, hemorrhage (2 ml per 100 gm body weight) induced a decrease in cardiac index which was significantly more marked in rats with liver denervation (-62 +/- 3%) than in sham-operated rats (-47 +/- 5%; p less than 0.05). This more severe response to hemorrhage may be due to a lack of portal territory vasoconstriction since the fraction of cardiac output reaching portal territory did not decrease during hemorrhage in rats with liver denervation (16 +/- 1% to 14 +/- 1%) but significantly decreased in sham-operated rats (from 15 +/- 1% to 11 +/- 1%, p less than 0.05), this value being significantly lower, after hemorrhage, in sham-operated rats than in denervated rats. The results confirm the lack of tonic neural influence on hepatic circulation during physiological experimental conditions and indicate that hepatic nerve function has a significant contribution to the overall cardiovascular homeostasis.