56 ELECTROLYTES IN BIOLOGICAL SYSTEMS 



and to overcome this difficulty presumably a high concentration in the external 

 medium would be advantageous. But on the other hand, too high an outside 

 concentration of a normally occurring intracellular component might have 

 detrimental efifects on the cell. Thus the ideal situation probably represents a 

 balance between these two opposing factors. In the experiments described here 

 a compromise was attempted by adding the ATP in small amounts at short 

 intervals. Since the potassium and sodium regulating mechanisms responded 

 differently in the other experiments it should not be surprising that they behave 

 differently here. 



Action of Phenyl Urethane and its Reversibility: Ulva. The presence of 

 io~^ m/1. phenyl urethane in the sea water around the cells caused a marked 

 progressive loss of potassium and gain of sodium over a 48-hour period (figs. 

 15 and 16). At 36 hours, when the cellular sodium was 275% of the original 

 value and the potassium 38%, some samples were transferred to running 

 sea water to determine the reversibility of these ion shifts. At 48 hours, when 

 these samples were removed, the cellular sodium concentration had been 

 restored to the normal level, while 78% of the potassium which had been lost 

 was reaccumulated. In other experiments, where potassium reaccumulation 

 was followed over a longer period, it was observed to be complete (to the 

 control level). 



The precise mechanism of action of the urethane series of narcotics has not 

 yet been clearly defined. Cornman (7) has recently reviewed the effects of these 

 narcotics with special reference to cell-division inhibition. Lamanna and 

 Campbell (21) have presented data which indicate that urethane inhibits 

 yeast-cell respiration by a surface action. But since these agents do inhibit cell 

 respiration the action of phenyl urethane was investigated here. The most 

 striking feature of this disturbance of cation regularity is its complete reversi- 

 bility. Experiments with metabolic inhibitors frequently are not shown to be 

 completely reversible as regards electrolyte disturbances; hence such experi- 

 ments are open to the criticism that the potassium loss and/or sodium gain 

 observed with inhibitors represents merely a general deterioration of the cell 

 with a resulting non-specific movement of cations with their concentration 

 gradients. The experiments presented here allow no such interpretation, for 

 certainly some active process must be involved in the restoration of potassium 

 and sodium to normal values after removal of the inhibitor. 



Influence of phenyl urethane: Valonia. The presence of io~'* m 1. phenyl 

 urethane in the sea water in the dark results in a loss of potassium and gain 

 of sodium. In 75 hours the cells have lost approximately 50% of their potassium 

 whereas the sodium content has increased 60%. At the time the ceils are trans- 

 ferred to light and running sea water a gradual reaccumulation of potassium 

 and secretion of sodium out of the cells begins and continues for approximately 

 75 hours, after which time the cells have reestablished essentially their normal 



