Abstract
Nitro and dinitrophenols have been shown to stimulate the metabolic processes of many types of cells 1 , 2 and to produce a reversible block to the cell division of fertilized eggs of a number of marine invertebrates. The analogous dihalo and trihalophenols exhibit similar properties when tested on marine eggs, but are unable to cause metabolic stimulation in intact mammals and other animals. 3
Various tissues were subjected to treatment with 4,6-dinitro-o-cresol and a number of dihalo and trihalophenols at a series of environmental temperatures, oxygen consumption of the tissues being measured with Warburg microrespirometers. 4 The tissues included: fertilized eggs of Arbacia punctulata and Nereis limbata; a commercial baker's yeast (Anheuser-Busch), and various rat tissues.
From the data in Table I concerning the effect of various concentrations of 4,6-dinitro-o-cresol on Arbacia at 12°C., 20°C., and 27°C., and on Nereis at 13°C., 20°C., and 28°C., it may be seen in each case that the optimum concentration for oxidative stimulation does not vary greatly with temperature. At the respective optimum concentrations, the number of units of excess oxygen taken up by the treated eggs increased as the temperature was raised. However, because of the greater rate of increase in oxygen consumption by the control eggs, the percentage stimulation decreased with increasing temperature.
Similarly, it is shown in Table II, that the percentage stimulation of oxygen consumption in yeast is larger at 15°C., or 20°C., than at 25°C., or 30°C.
The data of Table III show that each of 4 phenol derivatives gave a larger relative stimulation of lactate oxidation by rat kidney tissue slices at 20°C. than at the approximately physiological temperature of37°C.
The experiments on yeast and rat tissues recorded here demonstrate that the metabolic stimulating effects of dihalophenols and trihalophenols, which are relatively insignificant in the higher temperature ranges, are more readily recognized at lower temperatures.
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