100 



Mr. E. Ponder. The Hemolytic 



The Protective Action of Histamine. 



It has been shown that histamine possesses the accelerating action on the 

 haemolysis produced by sodium glycocholate, being in this respect similar to 

 the action of the serum albumin solution dealt with in the beginning of the 

 paper. It remains to be shown whether or not it has the protective action of 

 the serum albumin solution (Table IX). 



This is a simple matter, in view of the information conveyed in Table XIII. 

 The following experiment illustrates this : — 



To 1 c.c. of an active standard blood suspension, add 0T c.c. of 1 in 500 

 histamine. Allow this tube to stand for 5 minutes. 



If 0"2 c.c. of this suspension be added to glycocholate and histamine in a 

 tube, it will carry with it a small amount of additional histamine. For instance, 

 if 0*4 c.c. of glycocholate have added 0'2 c.c. of this suspension, and also 

 0'4 c.c. of 1 in 5000 histamine, the final dilution of histamine in the tube will 

 be 1 in 8330, instead of 1 in 12,500, which it would have been if instead of 

 this suspension containing histamine, a standard suspension had been used. 

 Consulting Table XIII, it will be seen that if 1 in 500 glycocholate be 

 employed for haemolysis, this slight increase in the histamine concentration is 

 of little consequence, altering the hfemolytic time only by 1 or 2 seconds. 

 Therefore the effect of a dilution of 1 in 500 glycocholate on the standard 

 suspension, before and after it has had histamine added in this quantity, will 

 decide whether or not the histamine has caused a protection of the blood 

 cells. 



To two tubes, then, add 0'4 c.c. of a 0*5 per cent, solution of sodium glyco- 

 cholate ; add in the ease of one tube, - 2 c.c. of standard suspension, and in 

 the case of the second, - 2 c.c. of the suspension containing histamine, as 

 prepared above ; after a 5 seconds' interval, add - 4 c.c. of 1 in 5000 histamine. 

 The tube containing the standard suspension hsemolyses in 30 seconds, that 

 containing the suspension, plus histamine, in 3|- minutes. This demonstrates 

 that the histamine has a protecting effect on the cells against hcemolysis by 

 the glycocholate-histamine system. 



If the cells of this suspension plus histamine be washed in saline in the 

 centrifuge, the suspension resulting from adding them to the appropriate 

 amount of saline is still slow in being hsemolysed by these quantities of glyco- 

 cholate and histamine. This demonstrates that, as in the case of the 

 protection conferred by serum albumin solution, the protection conferred by 

 the histamine is not due merely to the presence of the latter in the saline 

 surrounding the red cells, but due to some change produced in the cells 

 themselves. 



