A study on the effect of nicotine on hepatic regulations

吸烟对人体健康的影响主要是通过对肺部和心血管疾病的研究而得到普遍认可的。然而，吸烟对肝脏生理和病理生理调节的影响尚不清楚。研究了烟碱对大鼠肝循环的影响。用氨基甲酸乙酯麻醉大鼠，用压力传感器和激光多普勒血流仪测量肝门静脉压力和肝血流。术后状态稳定后，分别在腹腔和腹腔内给予尼古丁。门静脉内尼古丁输注诱导剂量依赖性门静脉压和肝血流升高。内皮素-1抗体预处理可消除肝循环的改变，内皮素- a或内皮素- b预处理可部分逆转肝循环的改变。此外，内皮素- a和内皮素- b联合预处理完全阻断门静脉内尼古丁输注对门静脉压力和肝血流的影响。脑内注射尼古丁也会引起剂量依赖性的门静脉压和肝血流升高。肝交感神经切除术或6-羟多巴胺预处理可消除这些肝脏循环的变化，但肝迷走神经切开术不能消除这些变化。

It is generally accepted that smoking affects human health mainly by studies on pulmonary and cardiovascular diseases. However, a little is known about an influence of smoking on hepatic physiological and pathophysiological regulations. An effect of nicotine on hepatic circulation was studied in rats. Rats were anesthetized with urethane and hepatic portal vein pressure and hepatic blood flow was measured by pressure transducer and laser Doppler flowmeter. Nicotine was administered intraportally and intracisternally after the stabilization of post-surgical state. Intraportal nicotine infusion induced dose-dependent increase portal pressure and hepatic blood flow. These changes of hepatic circulation were abolished by pretreatment of endothelin-1 antibody, and partially reversed by endothelin-A or endothelin-B pretreatment. Furthermore, combination pretreatment of endothelin-A and endothelin-B completely blocked the effects of intraportal nicotine infusion on portal pressure and hepatic blood flow. Intracisternal injection of nicotine also induced dose-dependent increase portal pressure and hepatic blood flow. These changes of hepatic circulation were abolished by hepatic sympatectomy or 6-OHDA pretreatment, but not by hepatic vagotomy.