The Biochemistry of Ferritin 209 



binding capacity. From these two values the degree of saturation of 

 the plasma iron-binding protein could be calculated. 



Fourteen dogs were bled by a standard procedure for inducing hemor- 

 rhagic shock. Of these, 9 died within 24 hours after terminating the 

 experiment by retransfusion of all the blood previously withdrawn. 

 Analyses of the last blood sample gave the following values: 



(a) Total iron: 287 (173-534) % of the original. 



(b) Iron-binding capacity: 15 (6-25) % of the original. 



(c) Saturation of iron-binding protein: 90 (80-97) % as contrasted 

 with 20 to 40 % for control values. 



Of the remaining 5 dogs in this series, one survived beyond 24 hours 

 but died subsequently, with values for the last blood sample similar 

 to those noted above. The remaining 4 dogs which survived showed 

 less marked changes for final plasma samples: 



(a) Total iron: 171 (142-216) % of original. 



(6) Iron-binding capacity: 46 (38-58) % of original. 



(c) Saturation of iron-binding protein: 70 (55-84) %. 



In contrast to these alterations, changes were barely evident in 

 another series of dogs pretreated with the adrenergic blocking agent 

 Dibenzyline* and then subjected to hemorrhagic hypotension of an 

 equivalent degree and duration. Dogs pretreated with Dibenzyline 

 usually survive this hemorrhagic procedure. There is evidence that 

 Dibenzyline exerts its protective effect by virtue of its blunting action 

 on the intense peripheral vasoconstriction which normally accompanies 

 hemorrhage, thus maintaining a better blood flow through the liver and 

 other splanchnic organs. Six dogs treated in this manner had plasma 

 values for the last sample as follows: 



(a) Plasma iron: 100 (50-150) % of original. 



(b) Iron-binding capacity: 86 (54-133) % of original. 



(c) Saturation of iron-binding protein: 40 (18-67) %. 



These results confirm the reality in vivo of the more labile ferrous 

 linkage to ferritin and emphasize the fact that in the reduced state 

 ferritin can liberate its iron for passage into the plasma, to be bound 

 by the plasma iron-binding protein. This process was readily demon- 

 strated in vitro by dialysis of partially purified plasma iron-binding 

 protein against several ferritins, each treated in such a way that they 

 contained differing quantities of ferrous iron (Table 10) . The greatest 

 quantity of ferritin iron was transported for binding by the iron-binding 



* N-Phenoxyisopropyl-N-benzyl-/3-chlorethylamine, manufactured by Smith, 

 Kline and French, Philadelphia. 



