Abstract
The effect of injection of sodium benzoate and sodium hippurate on the circulation through the glomeruli of frogs' kidneys was studied by Richards's 1 method of direct observation. Sodium benzoate, .008 to .020 mil of a ten per cent. solution per gram frog, invariably causes increased circulation through the glomeruli, increasing both the number of functionating glomeruli, the number of active loops in each glomerulus, and the velocity of flow in each capillary. Sodium hippurate, .008 to .020 mil of a fourteen per cent. solution per gram frog, had the opposite effect. This harmonizes with the work of H. B. Lewis, 2 and F. B. Kingsbury and W. W. Swanson, 3 who demonstrated that sodium hippurate was excreted more slowly than sodium benzoate in the mammal.
This phenomenenon is of particular interest because Bunge and Schmiedeberg 1 demonstrated that hippuric acid is synthesized from benzoic acid and glycocoll in the kidney, while hippuric acid merely passes through it. It is interesting to speculate upon the possibility that the process of synthesis may bring about or be associated with a local vasodilation.
Among other drugs studied, nitroglycerine, one five-thousand solution, theobromine, one per cent. solution, and sodium indigo sulphonate, one per cent. solution, increased the glomerular circulation in a similar manner; and indigo sulphonate definitely stained the glomerular capsule blue. This shows that sodium indigo sulphonate is excreted through the glomeruli as well as through the tubules. Heidenhain 2 had demonstrated the excretion of this substance through the tubules but not through the glomeruli. 3
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