Blood supply and O2 consumption of the small intestine in low flow

Blood flow and O2 consumption of the small intestine were studied anaesthetized cats in two series of experiments. Two-step haemorrhagic shock was applied in the first one; the intestinal vascular bed was locally hypoperfused in the other. Resistance to blood flow decreased in both haemorrhage and hypoperfusion. Intestinal blood flow was 12.6 ml/min . 100 g in haemorrhage (blood pressure 60 mm Hg) and 13.3 ml/min . 100 g at 50% perfusion. O2 consumption was only slightly reduced (93% and 89% of the control, respectively). Decrease in resistance showed a similar character to the "autoregulatory escape" phenomenon. Two types of regulation of O2 supply took place during low flow. The first one tended to maintain O2 supply to the gut in the face of flow reduction; in the other O2 consumption depended upon blood upon blood flow. The lower was blood flow, the more dominant became the second mechanism.