PHARMACOLOGY AND TOXICOLOGY OF SUPRARENALS 243 



Arey and Bigney describe this change as an expansion of the pigment 

 cells. 



The pigment cells of the frog's skin on the other hand are constricted 

 by epinephrin. This appears to be an effect similar to that caused in the 

 horned toad as it is due neither to anemia nor to a reflex (Lieben(&) ). 



The melanophore reaction of the horned toad has been carefully worked 

 out by Redfield(fr). He found that nervous excitement causes contraction 

 of the melanophores. This reaction is prevented in any area by a blocking 

 of the circulation or by removal of the suprarenals but not by severing 

 nervous connection. 



Response of Glands. Epinephrin stimulates secretion of the salivary 

 and lachrymal glands (Langley (a)). Denervation of the submaxillary 

 gland by cutting the chorda tympani and destroying the superior cervical 

 ganglion does not interfere with the reaction, therefore the point of stimu- 

 lation must be peripheral. Constriction of many seconds' duration pre- 

 cedes the dilatation which accompanies the secretion (Biedl(^r)). Atropin 

 in very large doses inhibits the secretion. 



Large doses of epinephrin excite secretion of the mucous glands of the 

 mouth, esophagus and trachea. A rise in blood pressure precedes the 

 secretion, which quickly reaches a maximum and gradually subsides 

 (Biedl). 



Langley says that epinephrin increases the output of a secreting pan- 

 creas but has little or no effect upon a quiescent organ. Mann and Mc- 

 Lachlin say that this hormone decreases pancreatic flow when any effect 

 is produced, even with doses which cause a fall in blood pressure. 



It is claimed that gastric secretion is also stimulated by epinephrin 

 (Yukawa). 



Respiratory Effects. Oliver and Schafer were the first to notice that 

 suprarenal extract causes either an arrest or a decrease in the amplitude of 

 the respirations. As shown later this was due to epinephrin. A first in- 

 jection causes a prolonged expiration which extends into a state of apnea 

 more or less persistent. The apnea is obtained more easily in anesthetized 

 than in conscious animals. Repeated injections of epinephrin at suffi- 

 ciently short intervals produce an action on the respiratory rhythm which 

 becomes less and less marked although the blood pressure response may 

 not change (Langley (a), Langlois and Garrelon). The decrease in the re- 

 spiratory effect is greater in an excess of oxygen. Section of the vagus 

 diminishes the duration of the apnea but does not suppress it. 



Of perhaps greater interest is the effect of physiological doses of 

 epinephrin. All of the earlier workers used large doses, far above any- 

 thing physiological. Nice, Rock, and Courtright using the contractions of 

 the diaphragm to indicate respiratory change made a study of this prob- 

 lem. They found that depressor doses as well as pressor doses up to a 

 certain point cause an increase in the depth of the respiration, the in- 



