Sympathetic nervous control of intramural blood flow in the feline and human intestines

Intramural blood flow and flow distribution in the feline and human intestines were investigated by means of a recently developed inert gas elimination technique during electrical stimulation of the regional sympathetic nerve fibers. The results obtained in man and cat showed qualitative and quantitative similarities. Thus, observations made on man strongly suggested that the intestine exhibited an autoregulatory escape from the vasoconstrictor fiber influence in the same manner as was seen in the cat. During the steady state phase of vasoconstriction induced by nervous stimulation at 8 Hz, blood flow in the mucosa-submucosa and in the muscularis was decreased to the same extent as was total blood flow in the cat, implying that flow distribution to these two major portions of the bowel remained unaltered. In man, the vasoconstriction was somewhat more pronounced in the muscularis than in the mucosa-submucosa. Hence, in man a comparatively larger fraction of total blood flow was diverted to the mucosa-submucosa during nervous vasoconstriction.