MUCOPOLYSACCHARIDES OF CONNECTIVE TISSUE 337 



does occur. As noted, however, hyaluronic acid does appear to be correlated 

 with the higher water content of the skin of young rats [52]. Further study 

 is necessarv to appreciate fully the effect of this shift on physical structure 

 of ground substance and the consequent influence on the metabolism of 

 cells imbedded therein. 



This method of analysis has been used to study further the effect of 

 insulin on the svnthesis of acid mucopolysaccharides. The turnover 

 studies discussed previously indicated that alloxan diabetes effects a 

 decrease in turnover rate of both hyaluronic acid and the chondroitin 

 sulphuric acid fraction. Analysis of skin from these animals confirmed a 

 suspected decrease in concentration of these substances. Table V indicates 



TABLE V 



Effect of Insulin on Mucopolysaccharide 

 Content of Rat Skin 



the results of these experiments. Noteworthy is the marked decrease in 

 hyaluronic acid concentration and a less striking decrease of chondroitin 

 sulphuric acid in contrast to heparin. The latter compound is actually 

 increased in the diabetic animals. This may be due to a relative decrease in 

 total ground substance. As in the turnover experiments, these effects were 

 reversed by insulin. It seems possible that this defect of mucopolysac- 

 charide metabolism in diabetes mav plav a role in the delayed wound 

 healing, decreased resistance to infection and accelerated degenerative 

 changes which occur in diabetes melitus. 



Of particular interest has been the study of the effects of thyroid 

 hormone on mucopolysaccharide metabolism. For this purpose propyl- 

 thiouracil was employed to inhibit synthesis of thyroid hormones in rats. 

 Table VI illustrates the results of such experiments. In contrast to previous 



