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PubMed1964

THE ELECTROOSMOTIC EFFECTS ARISING FROM THE INTERACTION OF THE SELECTIVELY ANION AND SELECTIVELY CATION PERMEABLE PARTS OF MOSAIC MEMBRANES.

It has been previously shown, theoretically and in model system experiments, that mosaic membranes composed of anion-selective (electropositive) and cation-selective (electronegative) parts interposed between electrolytic solutions of different concentrations give rise to local electrical circuits. In this work with model systems it is shown that these currents produce electroosmosis. In systems with permselective electronegative membranes and KCl solutions, the electroosmotic water transport was 16 moles/faraday. With the permselective electronegative membrane replaced by more porous electronegative membranes, the electroosmotic effects were about twice as high. With Li salts, the water transport was considerably larger. A system with a permselective electropositive membrane of 50 cm(2) effective area and an electronegative membrane of 120 cm(2) gave internally generated currents up to 20 ma. In extrapolating from the results with macromodels to effects with true mosaics, i.e. microsystems, it is stressed that current depends on the linear distance over which membranes interact. In true mosaic membranes, the current pathways will be of the same order as the dimensions of individual membrane microelements; the sum of all local microcurrents will be correspondingly larger than the current in the macromodel, and the electroosmotic effects will be proportionately greater. Electroosmotic effects with true charge-mosaic membranes may be of the same order or larger than the liquid transport by normal and anomalous osmosis which might occur across the individual parts of the charge-mosaic.

Biophysical Phenomena↗
PubMed1953

Osmotic homeostasis maintained by mammalian liver, kidney, and other tissues.

Osmotic pressure maintained by liver or kidney tissue measured by its water equilibrium with solutions of sodium chloride remains unchanged from 5 minutes up to 1(1/2) hours following removal of the tissue from the body. Then with autolytic increase of molecular concentration within the cytoplasm of cells it reaches a higher level. Osmotic pressure maintained by pancreas or submaxillary gland, as ascertained in the same way, remains unchanged during (1/2) hour and later increases. Liver tissue of rat, mouse, guinea pig, rabbit, and cat maintains an osmotic pressure greater than twice that of the blood, and kidney tissue maintains an osmotic pressure somewhat less than twice that of blood. Fasting throughout a period of 7 days has little influence upon osmotic pressure maintained by cells of liver or kidney. Low protein diet has been found to depress osmotic pressure of liver cells after about 4 weeks, and with degenerative changes in the parenchyma, notably fatty infiltration, this pressure has remained at a diminished level during approximately 90 days. Increase of pressure within the common bile duct and the changes following biliary obstruction are accompanied by depression of the osmotic pressure maintained by liver tissue and ligation of the ureter diminishes the osmotic pressure maintained by kidney tissue. In both instances osmotic pressure tends later to rise to its former level. The osmotic pressure maintained by liver or by kidney tissue preserves an approximately uniform level under normal conditions and may be little changed by conspicuous injury to the organ. When this osmotic homeostasis is impaired by severe injury the pressure maintained by the tissue returns to its former level with recovery from the injury.

Animals↗
PubMed1959

Electrokinetic membrane processes in relation to properties excitable tissues. II. Some theoretical considerations.

A quantitative theory is presented for the behavior of a membrane-electrolyte system subject to an electric current flow (the "membrane oscillator"). If the membrane is porous, carries "fixed charges," and separates electrolyte solutions of different conductances, it can be the site of repetitive oscillatory changes in the membrane potential, the membrane resistance, and the hydrostatic pressure difference across the membrane. These events are accompanied by a pulsating transport of bulk solutions. The theory assumes the superposition of electrochemical and hydrostatic gradients and centers round the kinetics of resistance changes within the membrane, as caused by effects from diffusion and electro-osmotic fluid streaming. The results are laid down in a set of five simple, basic expressions, which can be transformed into a pair of non-linear differential equations yielding oscillatory solutions. A graphical integration method is also outlined (Appendix II). The agreement between the theory and previous experimental observations is satisfactory. The applied electrokinetic concepts may have importance in relation to analyses of the behavior of living excitable cells or tissues.

Biological Transport↗