PHYSIOLOGY AND BIOCHEMISTRY OF SHOCK 429 



the administration of the second dose of antigen into sensitized guinea 

 pigs, protects the animals against anaphylactic shock. The effect of 

 potassium chloride in liberating adrenalin is antagonized by calcium 

 chloride; however, calcium chloride itself is reported to liberate 

 adrenalin (Katz and Katz, 1937). A synergism between calcium and 

 adrenalin is reported (Fenn, 1940) to exist. This synergistic effect 

 may, therefore, be of significance in explaining the protection afforded 

 to anaphylactic animals by calcium and epinephrine, the latter liberated 

 by the action of the former. 



Calcium appears to play a part in decreasing the permeability of the 

 cell membrane and the irritability of cells in general. In calcium 

 deficiency in higher animals a condition of hyperirritability develops 

 through an interference with the neuromuscular mechanism. Calcium 

 in excess, or in normal concentration, but in the absence of potassium, 

 lengthens systole at the expense of diastole, finally resulting in 

 calcium rigor. Potassium acts in a reverse manner if in excess or un- 

 balanced by calcium. Gradually the cardiac cycle becomes diastolic, 

 and heart ultimately comes to rest in the completely relaxed state. 

 Thus, for the normal beat of the heart, calcium increases contractility 

 and prolongs systole, and potassium, having a reverse effect, reduces 

 contractility and favors relaxation. These relationships may play a 

 significant role in the inhibition of the heart in anaphylactic re- 

 actions. 



c. Acidosis in Anaphylactic, Histamine, and Peptone Shock. 

 Eggstein (1921), and Hirsch and Williams (1922) reported that 

 acute anaphylactic shock in dogs is associated with an immediate 

 (within two to three minutes following the injection of antigen) and 

 progressive acidosis. The acidosis appears before the onset of recogniz- 

 able clinical symptoms of shock. When the carbon dioxide combining 

 capacity of the blood plasma falls below 25 volumes per cent the animal 

 usually dies. In a later study, Eggstein (1924) found also that the 

 alkali reserve of the blood plasma is greatly decreased in shocks pro- 

 duced by the intravenous injection of toxic 'proteoses and typhoid 

 vaccines in dogs and in human cases. A definite relationship between 

 the decrease in the alkali reserve of the plasma and the lowered blood 

 pressure in toxemia was noted. The animal's life was in danger when 

 the alkali reserve of the blood fell below 30 volumes per cent. 



Eppinger, et al. (1928) determined muscle lactic acid and the 



