Abstract
Summary
Maximal growth of Earle's Strain L cells is obtained by using 15-20% horse serum with a medium containing 0.5% lactalbumin hydrolysate. Rate of lactate formation decreases as pH decreases but remains constant if the suspension is adequately buffered with bicarbonate. Respiration continues as a straight line function with time even though pH decreases. Sera from different horses affects growth rate of tissue cultures differently and as a consequence a culture in one horse serum may contain more rapidly dividing cells than another culture in another horse serum. Young, rapidly growing tissue cultured cell strains respire and glycolyze at a greater rate than old ones. This difference in metabolic rate occurs even though the cells are washed free of culture medium and resuspended in balanced saline solution before the metabolic determination is made. Metabolic rate is related to growth rate. This can be easily demonstrated by simply growing the cells at 31°C even though the actual determination is made at 37.5°C. Metabolic quotients obtained on tissue cultures grown in serum, have little quantitative significance when considered alone, because serum is not chemically definable.
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