Capillary filtration in the small intestine of the dog.

The purpose of these studies was to determine the capillary filtration coefficient of the small intestine of anesthetized dogs by the gravimetric technique. Capillary filtration was produced by elevating venous pressure. Filtration rate increased as venous pressure was increased but the relation between the two was not proportional. At venous pressures greater than 10 mm Hg, filtration rate tended to reach a limit. As a consequence, the filtration coefficient decreased at higher pressures. Mean capillary pressure was estimated by the isogravimetric technique. When capillary pressure was 10 mm Hg, the filtration coefficient averaged 0.37 ml/min per 100 g and decreased to 0.11 when capillary pressure was elevated to 20 mm Hg. The reduction in filtration coefficient at high capillary pressures was apparently due to closure of precapillary sphincters. ADDITIONAL