Abstract
LONDON Royal Society, January 30. R. A. MCCANCE: Ex-perimental sodium chloride deficiency in man. Three subjects were subjected to a weighed diet containing minimal quantities of sodium chloride. Fluids were not restricted. The protein intake was augmented by incorporating ‘ashless' casein in the diet. Sweating was carried out in a radiant heat bath, and the sweat was collected quantitatively on mackintosh sheeting. Urine, faeces and insensible perspiration were also collected. The sodium, chloride, nitrogen and potassium balances were determined on two subjects. The deficiency, which was severe, led to a loss of 25-35 per cent of the body sodium. The symptoms were loss of the sense of flavour, considerable weakness and fatigue, a sense of constriction in the chest on the least exertion, and cramps. The subjects at first lost weight pari passu with sodium, but later the weight ceased to fall and thereafter fluctuated without reference to the sodium. Many of the symptoms and signs and also the blood changes closely reproduced clinical or experimental Addison's disease, but there were points of difference also, for example, no fall of blood pressure. As sodium chloride was restored, the weight rose, the nitrogen balance became positive, the blood urea fell, and health was regained. D. Y. SOLANDT: The measurement of accommodation in nerve. Experiments are outlined by which A. V. Hill's theory concerning the time constant of ‘accommodation’ in the electrical excitation of nerve is verified. The predicted linear relation between relative threshold and time-constant of exponential rise of current was found for certain motor nerves of frogs, fishes, crabs, lobsters and man. The slope of this line is the reciprocal of X, the time-constant of ‘accommodation’. Measures of X were thus obtained on a variety of nerves under various conditions. The sciatic nerves of normal ‘winter’ frogs showed an average value of X = 35 msec.; the average value for human ulnar nerve was 58 msec. Increasing the concentration of calcium or potassium in the environment of frog's nerve was found to lower X. Decreasing the calcium ion concentration raised X until, in the absence of calcium, it approached infinity. No other treatment (excepting changes in temperature) was found by which X could be raised. The effect of calcium on X is much greater than potassium. This shows that the time-constants of ‘accommodation’ and of ‘excitation’ are independent.
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Societies and Academies. Nature 137, 246–247 (1936). https://doi.org/10.1038/137246b0
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DOI: https://doi.org/10.1038/137246b0