THE EFFECT OF TEMPERATURE ON THE CALORIGENIC ACTION OF DINITROPHENOL IN NORMAL AND THYROIDECTOMIZED PIGEONS

¹ From the Carnegie Institution of Washington, Station for Experimental Evolution, Cold Spring Harbor, N. Y.

Alpha-dinitrophenol has less calorigenic action at 15° than at 30°C. when measured on normal fasting doves and pigeons. A low temperature (15°) affects the calorigenic action of dinitrophenol in ring doves in the same direction but to a notably less extent than it was found in another study to affect the calorigenic action of two anterior pituitary hormones (thyreotropic and prolactin).

In a pigeon completely thyroidectomized eight months earlier two-thirds of the surely lethal dose of dinitrophenol only slightly increased (50 per cent) thermogenesis at the "critical temperature" (30°C.) of the pigeon; at 15°C. similar dosage had little (10 to 13 per cent) or no calorigenic action. In a control normal pigeon increases of 94-156 per cent were obtained at 15°, and of 178 to 320 per cent at 30°C.

The proved capacity of low temperature to abolish and even reverse the calorigenic action of certain substances (endogenous and exogenous in type) is a challenging fact which now has no adequate explanation. Some relationships of the thyroid to this general problem are discussed.