THE INFLUENCE OF COLD ON THE CALORIGENIC ACTION OF DINITROPHENOL

¹ From the Department of Physiology, Stanford University, California

1. In anesthetized cats submerged in cold baths until their body temperatures were reduced, shivering is greatly decreased or abolished by injection of dinitrophenol, in spite of the continuation of the conditions normally evoking shivering. The drug therefore depresses the mechanism for chemical defense against cold.

2. The intensity of the calorigenic action of dinitrophenol, whether measured by the ratio of post-injection to pre-injection levels, or by the peak in metabolic rate, is greatest in the body temperature range of 33 to 35°C. Below 33°, though the absolute intensity is less, the proportional increase is of the same magnitude as at normal temperatures. The fall in absolute intensity is more than accounted for by the van't Hoff effect.

3. The method of calculation of the intensity of the drug's calorigenic action in the cold used by previous workers seriously underestimated this action, because of their use of a pre-injection control value including the oxygen cost of chemical defense, an item absent from the post-injection period.