Effect of osmotic pressure,Na+/K+ ratio and medium concentration on the enzyme activity and growth of L cells in suspension culture

Summary The effect of changes in osmotic pressure and in the Na⁺/K⁺ ratio on the doubling time, maximum cell population, enzyme activity, and isoenzyme distribution pattern in suspension cultures of L cells was determined. The growth of viable cells is relatively flat over a rather wide range of osmotic pressures (220 to 440 mOsm per kg). The presence of extra salt or sucrose beyond that needed to reach the minimum osmotic pressure (220) is detrimental to cell growth as reflected by a delay in the onset of logarithmic growth, a slower growth rate, a decreased maximum population, and accelerated death phase. Excessive K⁺ ion is toxic, but the level at which it is toxic interacts with osmotic pressure of the medium. Enzyme activity and isoenzyme distribution patterns for those enzymes studied did not vary as a function of osmotic pressure, ionic ratios, or medium concentration.