LEVINE, BIOCHEMICAL STUDIES OF SELENIUM 393 



PANCREATIC LIPASE 



Sodium selenate and potassium selenocyanate had no effect on pan- 

 creatic lipase. Sodium selenite had a slight inhibitory effect, which was 

 proportional to the concentration. Experiments carried on with selenium 

 dioxid and with selenic acid showed a marked increase in acid content. 

 The high results can be attributed to the hydroh'^tic stimulation of these 

 selenium acids. 



ALCOHOLIC FERMEXTATIO^T 



Selenium dioxid in concentrations of 0.5% had marked inhibitory ac- 

 tion on alcoholic fermentation. In a 2.5% solution fermentation occurred, 

 but was suppressed entirely in a 3% solution. Sodium selenite (alkaline) 

 inhibited the evolution of carbon dioxid. Selenic acid, even in a con- 

 centration of 0.04% exercised an inhibitory influence over zymase. Very 

 little carbon dioxid was evolved with a 0.2% solution, while solutions 

 containing 0.5% or over gave no evidence of carbon dioxid formation. 

 Sodium selenate accelerated alcoholic fermentation. The effect produced 

 b}^ potassium selenocyanate seemed to be variable, although, in general, 

 the inhibition produced by concentrations lower than 2.5% was slight. 



Toxic Effects of Selenium Compounds 



Selenium compounds are toxic to both plants and animals. Even con- 

 centrations of 0.01% inhibit germination and growth. Sodium selenate 

 is the least toxic of the compounds investigated. Beginning with the 

 most poisonous the sequence of toxicity for animals is hydrogen selenid, 

 selenious acid, selenic acid, sodium hydrogen selenite, sodium selenite, 

 potassium selenocyanate, sodium selenate and free selenium. Potassium 

 selenocyanate is more toxic than the corresponding potassium sulfo- 

 cyanate. 



In very minute doses selenium compounds have no effect on blood 

 pressure. In comparatively larger doses a marked fall in blood pressure 

 is observed in the case of selenious acid, selenic acid, normal sodium 

 selenite, sodium hydrogen selenite and sodium selenate, although with 

 potassium selenocyanate a considerable rise in blood pressure is induced. 



Selenium compounds, even in small doses, have a marked effect on 

 respiration. Breathing becomes prolonged, deep and labored, and as the 

 dose is increased respiratory paralysis sets in even before the heart stops. 

 Pulmonary edema, accompanied by exudation of large volumes of yellow- 

 ish fluid, precedes death in the case of selenious acid, sodium hydrogen 

 selenite^ sodium selenite and selenic acid. 



