288 ASCORBIC ACID 



the dilated walls. ^''^ Nungester and Ames"^ obtained results which suggested 

 the possibility of capillary leakage. Intraperitoneal exudates obtained from 

 scorbutic guinea pigs invariably contained large numbers of red blood cells 

 whereas red cells were never found in exudates having a vitamin C content 

 of over 0.45 mg. per 100 ml. 



Another factor which may influence the strength of the capillaries is the 

 integrity of the membrane surrounding them. Chambers and Zweifach"^ 

 showed the presence of a mucopolysaccharide in the connective tissue sheath 

 of the capillaries, and Penney and Balfour" pointed out that any failure in 

 the formation of mucopolysaccharide might result in the weakening of the 

 sheath, thus leading to hemorrhages. Gersh and Catchpole^^ have suggested 

 that the strength of the capillaries is determined in part by the basement 

 membrane surrounding them. They report finding evidence that depoly- 

 merization of this glycoprotein (membrane) occurs in scurvy and may lead 

 to a weakening of the capillary wall. Further investigation of this aspect 

 of the blood vessel problem Avill be awaited with interest. 



The permeability of the capillaries of scorbutic and normal guinea pigs 

 was studied by Elster and Schock.^-" The blue dye (T-1824) was adminis- 

 tered intravenously, and no qualitative or quantitative differences could 

 be observed in its distribution in the tissue except for extravasation into 

 the periarticular soft tissues in the scorbutic but not in the control animals. 

 Since they saw no evidence of capillary leakage, they concluded that capil- 

 lary permeability was not altered by ascorbic acid deficiency in the guinea 

 pig. However, as previously stated, results of Follis'"" and Nungester and 

 Ames-^ suggest the possibility of capillary leakage. Chambers and 

 Zweifach^^' are of the opinion that the intercellular cement of the capillary 

 wall determines the permeability to diffusible substances whereas Landis'-* 

 and Cowie et al}- hold that capillary permeability depends on the state of 

 the entire endothelium. The latter investigators concluded from radioactive 

 tracer studies that "diffusion rather than filtration is the predominant proc- 

 ess in the exchange of substances across the capillary wall." Elster and 

 Schock agree that it is possible that the intercellular cement could be 

 affected in scurvy even though diffusion of the dye is still normal and 

 their experiments do not definitely establish or exclude alterations in func- 

 tion of the intercellular substance. It seems quite possible to the writer 

 that structural changes on a submicroscopic level, such as alterations in 

 molecular orientation and/or destroying of linkages in basic constituents, 

 particularly at cell surfaces, could be involved in a functional change caus- 



"8 R. Chambers and B. W. Zweifach, Physiol. Revs. 27, 436 (1947). 



120 S. K. Elster and J. A. Schock, A7n. J. Physiol. 161, 283 (1950). 



121 E. M. Landis, Ann. N. Y. Acad. Set. 46, 713 (1946). 



122 D. B. Cowie, L. B. Flexner, and W. S. Wilde, Am. J. Physiol. 158, 231 (1949). 



