FUNCTION OF HEPARIN 



were killed and skinned, and as much subcutaneous connective tissue as possible 

 was scraped off. Representative tissue spreads were examined histologically 

 for mast cells, the remaining subcutaneous tissue (about 60 g.) in each group 

 being then pooled and assayed for histamine and heparin as previously de- 

 scribed (Cass et al, 1954) except that on this occasion we used the thiocyanate 

 method (Snellman et al, 1948) for the initial extraction before finally purifying 

 the heparin by the method of Charles and Scott (1933). 



Compound 48/80 in the dosage used produced widespread degranulation 

 and disruption of the mast cells in the dermis of rats, and almost complete loss 

 of its tissue histamine — a drop from 26 to 1 -5 ^g./g- tissue (94 per cent loss). 

 On the other hand, the total heparin content fell only from 10-0 to 4-7 i.u./g. 

 (53 per cent loss). Thus the almost complete release of histamine from the 

 subcutaneous connective tissue of the rat by compound 48/80 was accompanied 

 by a loss of only half the associated heparin, and even then there was no sign 

 of the release of heparin into the circulating blood; the clotting time remained 

 normal and no metachromatic material appeared in the urine. That the heparin 

 extracted from the control series did in fact possess anticoagulant activity was 

 confirmed by its action on normal rat blood in vivo and in vitro. Another 

 histamine-liberator, diaminodecane, has been found to act in similar fashion 

 (Braunsteiner et al, 1957). 



So far as present evidence goes, both the rabbit and the guinea pig resemble 

 the rat in their failure to show changes in blood coagulability during anaphy- 

 lactic shock (Adams, 1953). The time has surely come for us to acknowledge 

 the slenderness of the argument which links the dramatic events of peptone and 

 anaphylactic shock in one particular species, the dog, to the function of heparin, 

 and hence, of the mast cells in general. 



Mast cells and the connective tissues 



The problem thus remains: what becomes of the 'heparin' which is released 

 from the tissue mast cells in species other than the dog? We have noted earlier 

 that some of the metachromatic material from disrupted mast cells may be 

 disposed of locally by macrophages and fibroblasts, some may adhere to 

 adjacent connective tissue fibrils or cells, while some may be bound by the basic 

 histamine-liberator itself. Pure heparin can be shown to interact with soluble 

 collagen protein in vitro, but the resulting fibrils do not closely resemble the 

 fibrils of natural collagen (Morrione, 1952). However, Higginbotham and 

 Dougherty (1956) have recently confirmed, by an elegant technique, that 

 metachromatic granules released into the tissues from mast cells are quickly 

 phagocytosed and digested by nearby fibroblasts (Maximow, 1904; Brodersen, 

 1928). These workers have thus supplied an important piece of evidence for 

 the hypothetical scheme of the 'dynamics of the connective tissues' which I 



139 



