Abstract
The stimulating action of the dinitrophenols on the oxygen consumption of cells and tissues is generally thought to reside in an acceleration of metabolic processes involving 4 primarily the oxidation of carbohydrate. Dodds and Greville 1 showed that the extra oxygen uptake induced by 4,6-dinitro-o-cresol (DNC) in kidney slices had a R.Q. of 1. Ehrenf est and Ronzoni 2 demonstrated an increased oxidation of carbohydrate in yeast treated with dinitrophenol (DNP). Later 3 they demonstrated that DNP was without effect in iodoacetate poisoned muscle. Clowes and Krahl 4 showed that the R.Q. of sea urchin eggs in the presence of DNC remained at the level characteristic of untreated eggs, viz., 0.93 to 0.95. Field and Tainter 5 present data to show that the stimulation of respiration in yeast by DNC is maximal in the presence of glucose.
In view of the fact that most of the work dealing with the effects of dinitrophenols has been done on biological systems whose normal fuel is in the main carbohydrate, it seems advisable to investigate the effects of DNP and DNC† on the oxidative metabolism of the grasshopper embryo (Melanoplus differentialis) where metabolism is predominantly at the fat level. 6 This paper will present preliminary facts relating to the stimulating effects of DNP and DNC on respiration together with a description of the influence of carbon monoxide and cyanide on the increased oxygen uptake.
The method of preparing the embryos for experiments has been described previously. 7 O2 uptake was measured in the Barcroft-Warburg apparatus for a period of from 1 to 3 hours in order to obtain a normal rate of oxygen consumption, DNP was then added to the manometer contents from the side bulb and the effect of the addition noted for a second period of from 1 to 3 hours.
Get full access to this article
View all access options for this article.