Some observations on ‘autoregulatory escape’ in cat intestine

Abstract

''Auto-regulatory escape'' (Folkow, Lewis, Lundgren, Mellander and 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 O2 content. ''Autoregulatory escape'' was observed with sympathetic nerve stimulation and noradrenaline [norepinephrine] infusion. It did not occur during haemorrhage. The recovery of flow during norepinephrine infusion could not be explained by changes in intestinal motility or loss of effect of norepinephrine due to changes in portal venous hydrogen ion concentration. During a norepinephrine infusion there was a reduction in O2 consumption associated with a fall in blood flow. During the period of ''autoregulatory escape'', however, O2 consumption increased. The significance of these observations is discussed.