Springer Online Journal Archives 1860-2000
Chemistry and Pharmacology
Summary A densimeter technique was used to measure the rate of exit of thiourea from erythrocytes of various species of mammals. The cells were first equilibrated with a 200mm thiourea solution in 1% NaCl. An aliquot of these cells was added to 1% NaCl containing 4.6–23.1mm thiourea. Facilitated diffusion was demonstrated in each case. Using exit times or initial rates, calculations of half-saturation constants (ϕ) inmm and maximum transport rates (K) in isotones per min were made by three different methods. The following values were obtained: human −ϕ=60, 42, 35;K=1.2, 2.9, 0.9; rabbit −ϕ=46, 33, 32;K=0.8, 2.1, 0.8; mouse −ϕ=46,40, 30;K=3.4, 8.5, 3.2; rat −ϕ=65, 42, 23;K=6.1, 15.3, 3.7; ox −ϕ=107, 63, 88;K=0.6, 1.4, 0.4; sheep −ϕ=56, 38, 56;K=0.9, 2.2, 0.6; and pig −ϕ=110, 64, 49;K=1.6, 3.6, 1.1.
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