[Theory of microcirculation. 2. Problems of microcirculation from the viewpoint of the new theoretical concept]

Abstract

By means of network analysis and the use of a model which stimulates continuous blood supply to the tissue the basis of Starling's hypothesis of microcirculation is challenged. Contrary to the Starling's conception, we found that the microcirculation in the tissue is a stable process, whereby the interstitial hydraulic pressure (IHP) depends on the intracapillary blood pressure, on the permeability of the capillary wall, on the colloid-osmotic pressure and on the static pressure in the vessels and form a characteristic gradient along the capillary wall. The main effect of the colloid-osmotic pressure cannot be regarded as counteracting to the blood pressure, but instead consists in reduction of the IHP. Based on a theoretical conception about elastic interactions in the tissue a new method for measurement of the capillary filtration coefficients (CFC) is developed. Applying the method on the rabbit skeletal muscle the CFC is found to be 0.130 ml/min.mm Hg.100 g. This value is substantially higher than the values obtained from similar experiments reported in the literature (0.008 ml/min.mm Hg.100 g). The lymphatic fluid is not a result of a disbalance between filtration and resorption across the capillary wall, but it is a consequence of the protein recirculation in the following manner: blood vessels--interstitial space--lymphatic vessels--blood vessels. This recirculation is essential for the vital function of the tissue cells.