X. PHARMACOLOGY 377 



X. Pharmacology 



A. T. MILHORAT 



A. HEART 



A physiologic role of inositol in cardiac function is suggested by the 

 demonstration of the cyclitol in the heart muscle of rabbit, dog, sheep, 

 pig, and ox.^-^ The ventricle of the ox heart was found by Winter^ to con- 

 tain from 85.7 to 134.8 mg. of inositol per 100 g. of tissue, and the auricle 

 contained from 77.1 to 92.2 mg. Less inositol was found in the bundle of 

 His than in tissue from another part of the same ventricle. The inositol 

 content of the Purkinje fibers was 53 mg. per 100 g. of tissue. Winter^ 

 found the survival changes in the heart muscle of the dog to be accom- 

 panied by an increase in the inositol content and, therefore, postulated the 

 existence of a combined from of inositol, in addition to the free substance. 

 Moreover, since a combined form of inositol could not be detected in the 

 hearts of herbivorous animals such as the sheep and ox or in the heart of 

 the carnivorous pig, it appeared unlikely that the combined form in the 

 heart of the carnivorous dog was a substance such as phytin and had been 

 derived from plant sources in the food. His evidence for the presence of a 

 combined form of inositol in heart muscle is reminiscent of the experi- 

 ments of Rosenberger,^ who reported on the presence of both free and com- 

 bined inositol in the white mouse. Rosen berger's determinations were made 

 on the entire carcass after removal of the stomach and intestines (see also 

 reference 6). Whether the function of inositol in heart muscle is similar to 

 that in striated muscle, as postulated by Portmann, cannot be stated in a 

 definitive way at the present time. Portmann^ found that the fin muscles 

 of fish, and especially of the shark, contain large amounts of inositol. Since 

 the liver of these fish contains no glycogen or other reserve carbohydrate, 

 Portmann believed that the inositol probably is a reserve carbohydrate 

 that is formed from glucose and is stored in the fins to serve as an available 

 source of glucose for the blood by the reopening of the inositol ring. Sug- 

 gestive support of this hypothesis is furnished by the success of Grosheintz 

 and Fischer^ in the cyclization of glucose to inositol by purely chemical 



' J. Needham, Biochem. J. 17, 422 (1923). 



2 L. B. Winter, Biochem. J. 28, 6 (1934). 



3 L. B. Winter, Biochem. J. 34, 249 (1940). 



' L. B. Winter, /. Physiol. {London) 103, 27P (1944). 



5 F. Rosenberger, Z. physiol. Chem. 64, 341 (1910). 



« A. Taylor, M. A. Pollack, and R. J. Williams, Univ. Texas Publ. 4237, 41 (1942); 



V. H. Cheldelin and R. J. Williams, Univ. Texas Publ. 4237, 105 (1942). 

 ^ A. Portmann, quoted by H. O. L. Fischer, Harvey Lectures 40, 156 (1944-1945). 

 « J. M. Grosheintz and H. O. L. Fischer, Harvey Lectures 40, 156 (1944-1945). 



