Effect of 2-4 Dinitrophenol on Oxygen Consumption of the Rabbit Lens.

Abstract

Recent findings suggest that the therapeutic use of 2-4 dinitrophenol (DNP) in the treatment of obesity is followed in a small percentage of cases by the development of cataract., Since the etiology of cataract is obscure and since metabolic disturbances in the lens may play a part, an investigation of the action of this metabolic stimulant on the oxygen consumption of the lens was undertaken. Young white rabbits about 1 kg. in weight were used throughout. These were killed by a blow on the back of the neck and the lenses rapidly removed, care being taken to avoid injury to the capsules. Excised lenses were placed at once in small (6 ccm.) vessels belonging to a set of 4 differential Barcroft microrespirometers. The suspension medium was mammalian Ringer's solution containing 0.2% glucose, buffered at pH 72 with M/150 phosphate. The vessels were then filled with oxygen and immersed in a water bath at 30° ± 0.01 °C. The respirometer shaker was operated at a rate of 110 round trips per minute, with an excursion of 5 cm. Lenses were equilibrated for an hour under these conditions before measurement of respiration was commenced. These values of temperature and rate of shaking were maintained throughout. A total of 144 lenses was used in the 36 runs made. Each lens served as its own control for a 60-minute period. DNP (as sodium dinitrophenoxide) was then added from the sidearms to the experimental vessels, Ringer's to the controls. In no case did such addition result in significant change of pH. The oxygen consumption of the lens is relatively low. In cmm. oxygen (N.P.T.) per gm. wet weight per hour (QO2) the mean of 44 runs was 32.1 for the first hour of measurement.