Capillary size and density in the cerebral cortex of rats with a porto-caval anastomosis

Morphometric investigation by automatic image analysis of alkaline phosphatase positive brain capillaries was performed in control rats and in rats with a 30 days old porto-caval anastomosis. Rats with a porto-caval anastomosis showed an increased capillary diameter D_i and as a consequence of this a decreased capillary surface-to-volume ratio S_i/V_i. The free capillary distance was increased and the capillary length per unit brain volume L_Vi was decreased in the shunted rats compared to the controls. There was no difference in the percentage of the projected capillary area\(A_{A_i }\)% between the two groups. It is suggested that the dilatation of the capillaries in rats with a porto-caval anastomosis is caused by the altered haemodynamic properties with a low mean blood pressure although the cardiac output is increased and that the alteration in free capillary distance and length per unit brain volume L_Vi is caused by dispersion by cortical edema induced by the porto-caval anastomosis.