Some observations on 'autoregulatory escape' in cat intestine.

1. ;Autoregulatory escape' (Folkow, Lewis, Lundgren, Mellander & Wallentin, 1964a) in which intestinal blood flow escapes from the constrictor influence of splanchnic nerve stimulation, was investigated in the cat. Measurements were made of intestinal blood flow, movements and portal venous pH and oxygen content.2. ;Autoregulatory escape' was observed with sympathetic nerve stimulation and noradrenaline infusion. It did not occur during haemorrhage.3. The recovery of flow during noradrenaline infusion could not be explained by changes in intestinal motility or loss of effect of noradrenaline due to changes in portal venous hydrogen ion concentration.4. During a noradrenaline infusion there was a reduction in oxygen consumption associated with a fall in blood flow. During the period of ;autoregulatory escape', however, oxygen consumption increased. The significance of these observations is discussed.