A comparative study of the effect of drugs on activating and vasomotor responses evoked by midbrain stimulation: atropine, pentobarbital, chlorpromazine and chlorpromazine sulfoxide.
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Biomedical subjects
Publications and source records attributed to W R MARTIN.
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Sodium and potassium exchange has been studied in the blood of the sheep, dog, cow, and man. The potassium exchange rate in human cells is practically unaltered by increasing the plasma potassium concentration approximately threefold. Comparing the results in different species the exchange rate for potassium shows a rough correlation with the intracellular amount of the element. Expressed in per cent of the cellular content sodium tends to exchange more rapidly than potassium. In three instances the specific activity curves deviate from the simple exponential behavior of a two compartment system. In the exchange of potassium in canine blood the deviation is caused by the presence of a rapidly exchanging fraction in the buffy coat cells. Such an effect does not account for the inhomogeneity of sodium exchange in human blood.
The exchange of potassium between cells and plasma of heparinized human blood has been studied in vitro using the radioactive isotope K(42). The changes in cell and plasma specific activity are characteristic of a simple two-compartment system. The mean of seven determinations of the exchange rate at 38 degrees C. is 1.8 per cent of the cellular potassium per hour. The results indicate that at 38 degrees C. the rate is relatively insensitive to oxygenation or reduction of the hemoglobin, and to 1200 r of gamma radiation. With varying temperature the rate follows pseudo first order kinetics with a Q(10) of 2.35. Below 15 degrees C. the rate of loss of potassium exceeds the rate of uptake.