Vascular Reactions in the Small Intestine of the Cat during Hemorrhage

H aglund , U., Vascular reactions in the small intestine of the cat during hemorrhage. Acta physiol. scand. 1973. 59. 129–141. The reactions within the consecutive vascular sections of the cat small intestine during and after 2.5 h hemorrhagic hypovolemia was studied using a plethysmographic technique. The cats were bled 20 or 35 per cent of their estimated total blood volume. The animals bled 35 per cent were divided into a “shock” and a “non‐shock” group according to the level of blood pressure prior to retransfusion. Upon bleeding a moderate increase in intestinal blood flow resistance was observed but during the latter half of hypovolemia flow resistance decreased markedly in the “shocked” animals and was not normalized upon retransfusion. The capillary surface area available for exchange remained unchanged during the hypovolemia except in the “shocked” cats where a small increase was recorded. Tissue volume decreased rapidly upon bleeding due to a venoconstriction but late in the hypovolemia and after retransfusion a continuous tissue volume increase was often seen, partly due to a certain “pooling” of blood but mainly caused by transcapillary transfer of fluid. A great part of this fluid was found in the intestinal lumen at postmortem examination, which also revealed hemorrhagic lesions in the mucosa of most of the animals.