THE METABOLISM OF VOLUNTARY MUSCLE. L: THE EFFECT 

 OF PROLONCEL) EXCITATION OF MOTOR NERVES ON 

 THE CREATINE C(JNTEXT oV LIMB MUSCLES. By 

 W. n. Thomi'Son. (From the Physiology Laboratory, Trinity 

 College, Dublin.) 



{Received for -publication 2\si October U)1G.) 



Notwithstanding the amount of research that has been devoted to a 

 study of the changes produced by work in the creatine content of voluntary 

 muscles, it cannot be said that the matter is finally settled. 



Of the earlier investigators, Liebig (1847) (1), Sarakow (1863) (2), 

 Sczelkow (1806) (3), and Monari (1887) (4) all found an increase of 

 creatine after prolonged activit3\ On the other hand, Nawrocki (1865) (5) 

 found no increase in the tetanised muscles of the frog or fowl ; while Voit 

 (1868) (6) observed a decrease in those of the frog. Sczelkow drew his 

 conclusions from one experiment, while Nawrocki 's results were in- 

 constant; one of three experiments on frogs showed a marked increase 

 in the excited muscle. The methods employed by the earlier workers 

 were, moreover, defective. 



The results of recent workers are more uniform. Thus Mellanby 

 (1908)(7),vonFurthandSchwarz(1911)(8),andalsoScaffidi(1913)(9), 

 could find no change, while Graham Brown and Cathcart (1909) (10) 

 obtained in isolated frog's muscle a slight increase after tetanic excita- 

 tion. They found, on the contrary, a slight decrease in both the frog 

 and the rabbit, with the circulation intact. Lastly, Pekelharing and 

 Hoogenhuyze(1910)(ll) observed in the rabbit a decrease after section 

 of the limb nerves, whereas an increase was seen after section of the 

 posterior nerve roots. In the frog a decrease was obtained on tetanisation 

 of the limb muscles (deprived of circulation) ; on the other hand, an 

 increase with opening and closing shocks at the rate of 24 per minute. 



The problem has also been attacked from another side, namely, by 

 observing the effect of muscular work on the output of creatine and 

 creatinine in the urine. 



Of workers on these lines, K. B. Hofmann (1869) (12) observed no 

 effect from moderate exercise, while Grocco (1886) (13) found a marked 

 increase in the case of soldiers after a strenuous march. Gregor (14) 

 also observed an increase after strenuous work, as did Moitessier (1891) 

 (14a) on a constant diet after long walks. Both these findings were 

 VOL. XI., NO. 3. — 1917. 15 



