Effect of Venous Pressure on Mean Capillary Pressure and Vascular Resistance in the Intestine.

• It is well known that capillary pressure depends to a considerable degree upon venous pressure. Bayliss and Starling pointed out the importance of this reationship in 1894, but few studies have dealt with its quantitative aspects. Krogh et al. found that capillary filtration in the human forearm was influenced greatly by venous pressure, although changes of the latter were quantitatively less effective than an equivalent change of plasma colloid osmotic pressure. Pappenheimer and SotoRivera" observed with the gravimetric technique applied to the hind limbs of dogs and cats that a pressure change applied from the venous side appeared to be five to ten times more effective in changing capillary pressure than was a similar change of pressure when applied from the arterial side. It appears from their data that approximately 80% of a venous pressure increment is transmitted to the capillaries. In studies of capillary filtration in skin and muscle it is generally assumed that the figure of 80% applies. Folkow et al. have assumed that 85% of the venous pressure increment is transmitted to the capillaries in the intestine.