[In vitro contractility behavior of portal veins in normal rats and in rats with liver cirrhosis--effect of calcium antagonists and octreotide].

According to Poiseuille's law portal pressure is inversely related to r4. Thus, minor changes in radius dramatically influence intravascular pressure. Since the radius is actively regulated by contraction, this study elucidates in vitro contractility patterns of portal veins from healthy and liver cirrhotic rats. The results demonstrate that contractility amplitudes of portal veins from cirrhotic rats are increased in comparison to healthy animals. Calcium antagonists reduce amplitude and motility both in cirrhotic and healthy rats to the same degree. The same holds true for octreotide but significantly more in the cirrhotic group. Obviously, the maintenance of portal hypertension is supported by an active element of the portal vein, which can be controlled in vitro.