Scientific research in molecular biology has made it possible to make a qualified advance considered by many as the most important of the 20th century for the treatment of dehydration, mainly for infectious diarrhea due to viruses or enteropathogenic bacteria. This advance was the discovery of the molecular mechanism of co-transport sodium glucose (SGLT), a protein present in the membrane of the intestine cells and responsible for the incorporation of sodium associated with glucose, since the sodium is the most important ion in the osmotic balance for incorporate water.
The intestine is able to absorb electrolytes like sodium thanks to three molecular mechanisms. However, two of them are affected by gastrointestinal diseases being SGLT1 the only active, despite the gastrointestinal condition present. Oral rehydration therapy (ORT) is based precisely on this mechanism, capable of introducing into the enterocyte (intestinal epithelial cell) sodium and glucose in a ratio of 1: 1 which facilitates not only the absorption of the ion but also that of the Nutrient. Once in the enterocyte the sodium and glucose are separated from the transporter and pass into the bloodstream through the basement membrane creating an osmotic imbalance compensated by the incorporation of water into the body.
For an optimum absorption, the composition of the oral rehydration solution is essential, since the amount of liquid absorbed depends on three factors: sodium concentration, glucose concentration and osmolality of the liquid. The maximum water uptake occurs with a sodium concentration of 40 to 90 mmol / L, a glucose concentration of 110 to 140 mmol / L (2.0 to 2.5 g / 100 ml) and an osmolality of approximately 290 mOsm / L equal to the osmolality of body fluids. Increasing sodium beyond 90 mmol / L may produce hypernatremia; increasing the glucose concentration above 200 mOsm/L or increasing the osmolality of the solution can result in a net loss of water.