ELECTROLYTES AND THEIR ACTION 



211 



that Ringer's solution of the following composition is the most satisfactory for 

 the heart of the frog : 



NaCl 

 KC1 

 CaCl 9 

 NaHtJO, 



0-65 

 0-014 

 0-012 

 0-02 



NaH 2 PO 4 

 (Glucose) 

 Water - 



0-001 

 (0-2) 

 to 100 



This solution has a hydrogen ion concentration of 10~ 83 . 



The osmotic pressure of the blood of warm-blooded vertebrates is higher than 

 that of the frog, so that the concentration of the salts must be slightly raised. 

 For the isolated mammalian heart, Locke (1900) found the following composition 

 to serve well : 



NaCl 

 KC1 



CaCL 



0-9 



0-042 



0-024 



NaHC0 3 

 (Glucose) 

 Water - 



0-01-0-03 

 (0-1-0-25) 

 to 100 



The addition of glucose is of advantage as a source of energy, unless there is 

 objection to its presence for other reasons. For mammals, this solution must 

 be thoroughly oxygenated, conveniently by blowing oxygen from a cylinder 

 of compressed gas through a Berkefeld filter immersed in the solution, as 

 suggested by Keith Lucas. The solution used by Locke should be called 

 Ringer- Locke's solution. 



Tyrode (1910) adds a small amount of a salt of magnesium and bicarbonate, 

 obtaining the following solution : 



NaCl - 0-8 NaH 2 PO 4 - 0-005 



KC1 0-02 NaHCO 3 0.1 



CaCl 2 - 0-02 Glucose - - O'l 



MgCl 2 0-01 Water to 100 



This solution is a good one for the intestine of the rabbit, but the addition 

 of magnesium does not appear to be of any advantage for the heart, as pointed 

 out by Locke (1900). The last solution may be called Ringer-Tyrode's solution. 



The addition of bicarbonate is of value in assuring that the solution shall be 

 only just on the alkaline side of neutrality, while possessing the capacity of 

 neutralising acid products formed by the 

 metabolism of the organ perfused. The 

 description of the bicarbonate and phos- 

 phate systems, given above, has shown us 

 how this may be done. 



The work of Clark (1913, 2) on the 

 heart of the frog has shown that con- 

 tinuous perfusion with renewed supplies 

 of a pure saline solution removes some 

 important constituent from the cells ; thus, 

 a small volume of Ringer's solution, which 

 has been repeatedly circulated through a 

 heart, is capable of reviving another heart, 

 whose beats are reduced owing to con- 

 tinuous perfusion (Fig. 64). The substance 

 in question seems to be of a lipoid nature, 

 since it has considerable power of lowering 

 the surface tension of water, and a sub- 

 stance having a similar action can be 

 extracted by ether from the residue left on 

 evaporation of blood serum. The residue left on evaporation of the ether has a 

 great effect in causing recovery of a heart which has become "hypodynamic" from 

 prolonged perfusion with Ringer's solution (Fig. 65). This power is also present 

 in lecithin. The interaction of calcium is necessary for the effect, which seems 

 to be due to a change in the colloidal constitution of the cell membrane, which, as 

 we have seen, undoubtedly contains a large proportion of lipoids. 



FIG. 64. 



A, Frog heart after perfusion for four hours with 

 Ringer's solution. At the gap, where 10' is 

 marked, 2 e.c. of Ringer's solution, which had cir- 

 culated for twelve hours backwards and forwards 

 through another heart, were added to the 2 c.c. 

 already circulating. The result shows that some 

 important substance is removed from the muscle 

 by continuous perfusion with saline solutions. 



(Clark, 1913, 2, p. 98.) 



