56 P-AMINOBENZOIC ACID 



histamiiie-resistant patients. This effect occurred following either oral or 

 parenteral administration of PABA. 



4. Nervous System 



PABA may exert a mild sedative effect in certain autonomic nervous, 

 extrapyramidal, Parkinsonian, and choreic syndromes, tics, and epilepsy, 

 according to a recent report by Morpurgo and Fachini.'" 



5. Muscle 



Torda and Wolff'^^ observed no effect of PABA on acetylcholine sen- 

 sitivity of muscle. Survival of frog muscle and nerve after somatic death 

 was found by Sollman^^ to be prolonged by PABA. 



6. Enzyme Systems 



a. Cholinesterase 



In physiologic concentrations, PABA inhibited serum cholinesterase by 

 10 to 30 %, according to Zeller.^° This may account for the acetylcholinergic 

 action of PABA reported by Danielopolu.'*^ The weak effect of PABA on 

 serum cholinesterase of humans was confirmed by Paget and Dhellemmes.'*- 

 However, Koelle*^ reported no protective action by PABA against inactiva- 

 tion of brain cholinesterase by diisopropyl fluorophosphate. 



b. Tyrosinase 



The in vitro destruction of epinephrine by tyrosinase w^as shown by 

 Martin et al.^^ to be inhibited by PABA. 



c. Phosphatase 



PABA apparently depresses phosphatase in certain locations but stim- 

 ulates in others. Tamayo and Cuellar'*^ and Javier de Elio and Felix Sanz 

 Sanchez^^ reported inhibition of serum phosphatase, and Silver and Gold- 



" E. Morpurgo and G. Fachini, Acta Vituminot. 4, 210 (1950). 



38 C. Torda and H. G. Wolff, Am. J. Physiol. 145, 608 (1946). 



^^T. Sollman, J. Pharmacol. Expll. Therap. 90, 1-4 (1947). 



•'0 E. A. Zeller, Helv. Chim. Acta 25, 216 (1942). 



" D. Danielopolu, Ada Med. Scand. 118, 1 (1944) [C. A. 39, 2563 (1945)]. 



« M. Paget and G. Dhellemmes, Compt. rend. 224, 503 (1947). 



" G. B. Koelle, J. Pharmacol. Exptl. Therap. 88, 232 (1946). 



^^ G. J. Martin, C. T. Ichniowski, W. A. Wisansky, and S. Ansbacher, Am. J. Physiol. 



136, 66 (1942). 

 «M. L. Tamayo and F. T. Cuellar, Analesfls. y. quim. (Madrid) 40, 1322 (1944). 



[C. A. 42, 7448 (1948)]. 

 ■"* F. Javier de Elio and F. Felix Sanz Sd,nchez, Farmacotcrap. actual (.Maitrid) 3, 



468 (1946). 



