Osmotic Homeostasis Maintained by Mammalian Liver, Kidney, and Other Tissues

Abstract

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 1½ 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 ½ 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.

Bile duct epithelial tight junctions and barrier function

“…Similar to other organ systems, liver maintains osmotic homeostasis 11 . Obstruction of common bile duct leads to disruption of osmotic pressure in the liver.…”

The Relation of Urea to the Movement of Water in Liver Tissue

“…The medium is hypotonic for liver tissue but when its molar concentration is increased two-fold by addition of sodium chloride isotonicity may be maintained during one or two hr. 4 Water movement measured in per cent of weight before immersion varies widely with oxygen supply to the medium. With abundant oxygen under conditions that promote its diffusion throughout the medium and into the tissue, water enters rapidly during about one hr but later is lost and within 2 or 3 hr may be less than that before immersion.…”

Osmotic Activity of Tissues During Fetal and Postnatal Growth

“…The isotonicity of the maternal liver during pregnancy varied from 0.244 to 0.331 molar sodium chloride, the average being 0.285 molar. This figure is less than that of the normal adult liver (1,2).…”

“…When the tissues are immersed in solutions of sodium chloride of graded concentration from 0.I to 0.5 molar water movement quickly reaches an equilibrium which is maintained during a period of approximately 15 minutes; later, doubtless as the result of injury, there is increased permeability of the tissue. Water movement during 10 minutes of immersion has been found to be constant in tissues tested from 5 to 90 minutes following their removal from the living body (2).…”