Early changes in blood-brain barrier permeability after porto-caval shunt and liver ischaemia

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Abstract
Brain edema, distribution space (DS) and brain uptake index (BUI), of L-glucose, inulin, vitamin B12 and of 3 polypeptide hormones of increasing MW (angiotensin-I, gastrin and insulin) were measured in the rat after sham operation, portocaval shunt (PCS) or liver ischemia. At an early stage following PCS or liver ischemia, brain edema was not constant and was only demonstrable after liver ischemia in a large number of animals. Substances without an active transport and with a low diffusion coefficient such as L-glucose and inulin had a very low BUI, unchanged even if the 3H2O brain content or the DS were modified. Vitamin B12, DS and BUI were very high and did not change after liver ischemia or PCS. Insulin DS and BUI were low in the 3 groups of animals, whereas it decreased after PCS for gastrin. A significant increase of BUI and and DS (without any cerebral edema) was demonstrated for angiotensin-I, a polypeptidase hormone of 1300 MW. This polypeptidic marker is in the same MW range as the preliminary, recently recognized medium-sized molecules which may be involved in the pathogenesis of encephalopathy during experimental acute liver failure. Not only the MW, but the nature of such polypeptides may be of importance in the genesis of this limited impairment of BBB [blood-brain barrier] permeability.