Isotónico

Isotónico refers to a solution that has the same osmotic pressure as a biological fluid, such as blood plasma. This means that the concentration of solutes in the solution is equivalent to that found within cells or the bloodstream. This property is crucial for medical and scientific applications where maintaining cellular integrity and function is important.

In medicine, isotonic solutions are commonly used for intravenous fluid administration. Saline solutions, specifically 0.9% sodium chloride (normal saline), and Lactated Ringer's solution are classic examples of isotonic fluids. These are administered to patients to rehydrate them, correct electrolyte imbalances, or as a vehicle for delivering medications, without causing significant shifts in water movement across cell membranes. If a hypotonic solution (lower solute concentration) were administered, water would move into cells, potentially causing them to swell and burst. Conversely, a hypertonic solution (higher solute concentration) would draw water out of cells, causing them to shrink.

Beyond medical uses, the concept of isotonicity is important in cell culture, where the surrounding medium must be isotonic to the cells being grown to maintain their viability. In sports and exercise physiology, "isotonic drinks" are beverages designed to replenish fluids and electrolytes lost through sweat. While often labeled isotonic, their actual osmotic pressure relative to body fluids can vary. These drinks aim to provide carbohydrates for energy and electrolytes like sodium and potassium to aid in rehydration and muscle function.