[Effect of alcohol on organ microcirculation: its relation to hepatic, pancreatic and gastrointestinal diseases due to alcohol].

Although alcohol is well recognized as a systemic toxin, the enteric manifestations of alcohol abuse have only recently begun to be elucidated at the cellular and microvascular levels. Since the microvascular mechanism of the toxicity of alcohol has progressively been revealed, clinical applications of this research field should increase the availability of therapeutic options for alcohol-induced injuries of liver, pancreas and gastrointestinal (GI) tract. A high concentration of ethanol reduces GI and pancreas blood flow. Ethanol-induced GI hemorrhage, GI ulcer, and pancreatitis are initiated by the microcirculatory disturbance of GI mucosa and pancreas. Ethanol administration induces an increase in vasoactive agents such as endothelin and nitric oxide and oxidative stress. They appear to be involved in ethanol-induced GI and pancreatic injury. Regarding the effects of ethanol on the liver, small amount of ethanol increases hepatic blood flow, and prevents gut ischemia/reperfusion (I/R)-induced hepatic microvascular dysfunction and subsequent liver injury. While large amount of ethanol itself causes hepatic microvascular dysfunction, and aggravates the gut I/R-induced hepatic microvascular dysfunction and subsequent liver injury. Vasoactive agents and oxidative stress also appear to be involved in the liver injury. In endotoxemic animals, even small amount of ethanol causes hepatic microvascular dysfunction. Chronic ethanol consumption aggravates endotoxin-induced hepatic microvascular dysfunction. Chronic ethanol consumption aggravates gut I/R-induced leukostasis in the liver and hepatocellular injury associated with an enhanced expression of adhesion molecules, while it prevents the gut I/R-induced sinusoidal perfusion injury. Thus, effects of chronic ethanol consumption on the I/R injury are still controversial.