378 INOSITOLS 



means, and by the demonstration by others that inositol in the organism 

 can be converted into glucose. Although Mayer^ had found no increase in 

 the amounts of liver glycogen of three rabbits given 10 g. of inositol, nor had 

 he observed an increase in urinary glucose of diabetic patients given as much 

 as 50 g., Greenwald and Weiss^" later found a small but unmistakable in- 

 crease in the urinary glucose : nitrogen ratio when inositol was administered 

 to dogs with phlorhizin diabetes. Perhaps pertinent to this problem are the 

 observations of Needham.^^ who found that the injection of glucose into 

 the fertilized unincubated egg causes a very large rise in the inositol con- 

 tent of the egg during its subsequent development. More recently, Stetten 

 and Stetten^^ demonstrated a transformation of weso-inositol into glucose 

 in the phlorhinized rat, when they found significant concentration of 

 deuterium in the urinary glucose after administration of deuterio-inos- 

 itol. The differences in the results and interpretations of the earlier 

 workers, using less definitive methods, are easily understood when one 

 considers that the data of Stetten and Stetten indicate a transformation 

 to glucose of only 7 % of the administered meso-inositol. Moreover, in this 

 experiment the inositol was administered by intraperitoneal injection, 

 whereas the earlier investigators used the oral route by which absorption is 

 incomplete. 



The original observations of Sachs^^ that inositol affects cardiac function 

 was confirmed by subsequent workers. Sachs perfused the frog's heart 

 with Ringer's solution and noted increased amplitude and rate of con- 

 traction when inositol in low concentrations was added to the perfusion 

 fluid. However, when an isotonic solution of inositol was substituted for 

 the Ringer's solution containing inositol, the heart immediately was stopped 

 in systole. Hewitt and de Souza^^ employed approximately the same con- 

 centrations of inositol in their perfusion studies on the frog's heart. The 

 heart responded rapidly to inositol by an increase in the force of its beat 

 and just as rapidly returned to its original state when the inositol was 

 replaced by Ringer's solution alone. In six of the twenty-five experiments, 

 inositol had no apparent effect on the heart, and in two its perfusion led 

 to diminution in force of beat. The rate of the heart, as a rule, was not 

 altered by inositol. The action of inositol was considered to be on the 

 heart muscle, since the effects were noted also in the atropinized heart. A 

 concentration of 6%, such as was employed by Sachs, was found to be 

 strongly toxic and soon stopped the heart in systole. Brissemoret and 



9 P. Mayer, Biochem. Z. 2, 393 (1907). 

 1" I. Greenwald and M. L. Weiss, /. Biol. Chem. 31, 1 (1917). 



11 J. Needham, Biochem. J. 18, 1371 (1924). 



12 R. Stetten and D. Stetten, Jr., J. Biol. Chem. 164, 85 (1946). 



13 F. Sachs, Pflugers Arch. ges. PMjsiol. 115, 550 (1906). 



"J. A. Hewitt and D. de Souza, J. Physiol. (London) 54, CXIX (1921). 



