Effect of changes in vascular tone on the haemodynamic characteristics of the portal vascular bed of the isolated perfused rat liver.

Abstract

The effect of altered vascular tone on the haemodynamic characteristics of the intrahepatic portal vascular bed was studied in the isolated perfused rat liver preparation. The relationship between portal venous inflow (Q) and portal perfusion pressure (P) was determined in the presence of a maximally effective concentration of a vasoconstrictor agent (noradrenaline, NAmax, 3 x 10(-5)mol/L), an intermediate concentration (NAmed, 1 x 10(-6)mol/L) or a vasodilator agent (papaverine, PAP, 6 x 10(-4)mol/L). At flow rates greater than 20 mL/min, the pressure-flow relationship could be regarded as linear (P < 0.001), with mean values for the extrapolated intercept with the pressure axis (Po) of 6.8..