Colonic blood flow in cat and man as analyzed by an inert gas washout technique

An inert gas elimination technique for studying blood flow and flow distribution in the colon was developed on the cat and applied to patients during abdominal surgery. The method involves recording of the elimination of intra-arterially injected 85Kr from a colonic segment whereby the gamma- and beta-radiation of the tracer is registered simultaneously by a scintillation detector and Geiger-Muller tube, respectively. Total blood flow was determined from the recording of gamma-radioactivity using a modification of Zierler's formula, and muscularis blood flow as calculated according to Kety from the mono-exponential elimination recorded by the Geiger-Muller tube. The relative weights of the muscularis and mucosa-submucosa were determined from dissections or histological sections. With these weights and total and muscularis blood flows, flow in the mucosa-submucosa was calculated. Total colonic blood flow was 18 +/- 2 ml per min and 100 g of colonic tissue (mean +/- SE; n = 21). In the muscularis layer blood flow amounted to 11 +/- 1 ml per min and 100 g of muscularis tissue (n = 12), and flow in the mucosa-submucosa was calculated to be 28 +/- 5 ml per min and 100 g of mucosal-submucosal tissue. A major fraction (66 +/- 6%) of total blood flow was distributed to the mucosa-submucosa. As total colonic blood flow was enhanced the increase in flow was diverted only to the mucosa-submucosa. The feline and human large bowel exhibited great qualitative and quantitative circulatory similarities.