BKP-04

Total human liver blood flow represents approximately 25% of the cardiac output, up to 1500 ml/min. Hepatic flow is subdivided in 25-30% for the hepatic artery (500 ml/min) and the major part for the portal vein (1000 ml/min). Assuming a human liver weighs 1500 g, total liver flow is 100 ml/min per 100 g liver. Comparing this normalized flow rate to other species, it can be concluded that total liver blood flow is 100-130 ml/min per 100 g liver, independent of the species. The ratio of arterial:portal blood flow, however, is species-dependent. The hepatic artery originates directly from the descending aorta, and is therefore saturated with oxygen. It accounts for 65% of total oxygen supply to the liver. The hepatic artery also plays an important role in liver blood vessel wall and connective tissue perfusion. It also secures bile duct integrity. The blood from the portal vein is full of nutrients derived from the intestine and allows the hepatocytes to perform their tasks. Blood from the hepatic artery and the portal vein joins in the sinusoids. However, recent studies by others as well as our own observations, have revealed that there are both common and separate channels for arterial and portal blood. The hepatic artery perfuses the liver vascular bed in a ’spotty’ pattern, while the portal vein perfuses the liver uniformly. The liver is able to regulate mainly arterial flow by means of so-called sphincters, situated at the in- and outlets of the sinusoids. One of the most important triggers for sphincter function is the need for constant oxygen supply. If the rate of oxygen delivery to the liver varies, the sphincters will react and the ratio of arterial:portal blood flow alters.