The effect of veratrine on the heat production of medullated nerve

Abstract

Graham and Gasser (1931) have recently investigated the effect of veratrine upon the electrical response of frog's medullated nerve. The prolonged after-potentials which they observed led Professor Gasser to suggest that it would be interesting to examine also the effect on the heat production. In muscles (Hartree and Hill, 1922) the prolonged veratrine contracture is associated with a prolonged evolution of heat of the same order of size as in a tetanus developing the same force. It has been found that in nerve also, when fully veratrinized, a prolonged production of heat occurs in response to a single shock, and that the total amount of this heat may be many hundreds of times as great as that in the response of a normal nerve. Graham and Gasser used R. pipiens , I have used autumn Hungarian R. esc . They made up their veratrine in solutions of suitable strength and applied it to the nerve with a brush. The necessity of thermal equilibration demanded that my nerves should be soaked. I have used veratrine hydrochloride in Ringer's solution hundreds with phosphate to P h 7.2, of concentration about 1/50,000, and the nerves were usually soaked in this on the thermopile for about 1 hour.