208 



PRINCIPLES OF GENERAL PHYSIOLOGY 



ising the injurious effect of the pure sodium chloride (Fig. 62). A solution capable 

 of maintaining the heart beat at a satisfactory height for a considerable time was 

 thus obtained, but, from what has been said in the previous pages of the present 

 chapter, it is not surprising to find, as Ringer himself did, that the addition of a 

 small amount of sodium bicarbonate was beneficial. The investigator himself 

 pointed out that this addition had the effect of producing a slight alkalinity 

 similar to that of the blood, and of neutralising acid produced in the contractions 

 of the heart muscle (see 1882-83, 2, p. 223). The amount used was 5 c.c. of a 1 

 per cent, solution to 100 c.c. of the circulating fluid. 



Although the electrolytic dissociation theory was unknown at the time these 

 experiments were made, it was clearly recognised by Ringer that the effects of 

 calcium and potassium salts were due to the calcium and potassium components of 

 the salts added. He himself used indifferently carbonate, sulphate, phosphate and 

 chloride of calcium. 



In view of the fundamental importance of these facts, the simplest way of demonstrating 



&A.+ 



4- 4- 



Fig ft C. 



FIG. 62. ANTAGONISM OF CALCITM AND POTASSIUM. 



13. .4, Normal beats. 



!::./>'. Effect of adding calcium. The first three beats show the prolongation of the systole. 



At the arrow, 3 minims of 1 per cent, potassium chloride were added to the solution. The calcium effect 



is partially abolished. 

 13.C, Addition of a further 2 minims of potassium chloride solution. The beat becomes quite normal. 



(Ringer, 1882-83, 1.) 



them may be described. The heart of the frog or the tortoise is tied on to a cannula inserted 

 into the ventricle through the auricle by the method of Symes (1911). The way in which 

 the effect of different electrolytes can be shown will best be understood from the description 

 of an actual experiment. A tortoise heart was used and a tracing taken, by a lever attached 

 to the apex of the ventricle, before any perfusion fluid was introduced (Fig. 63). The beats were 

 small, as frequently happens, a. Perfusion was then commenced with a solution containing 

 0'75 per cent, sodium chloride and OK)1 per cent, sodium bicarbonate, b. The beats were not 

 improved, and would probably have ceased, if the perfusion with this solution had been 

 continued. Portions of the tracing are omitted for want of space. At c, a solution consisting 

 of 100 c.c. of the previous one, to which 3 c.c. of decimolar calcium chloride had been added, 

 was perfused. This contained a sb'ght excess of calcium above the normal one. An immediate 

 improvement is to be noticed, but relaxation is incomplete, as shown by the gradual risi- in 

 the level of the diastolic position. 6 c.c. of decimolar potassium chloride were then added 

 to the solution already containing sodium and calcium. The tonic action of the calcium was 

 removed, and, after a minute or two, the tracing d was obtained, showing a regular, powerful 

 beat, which would have continued for a long time. At e, the solution containing sodium alone 

 is returned to ; the small irregular beat reappears. At /, potassium chloride, in the same 

 proportion as before, is added. No improvement in the beat results, but the characteristic 

 relaxing effect of potassium in the fall of the diastolic position is observed. At y, calcium 

 chloride is added to the mixture in the same proportion as before, and we see the powerful 

 regular beat produced by the normal Ringer solution, containing sodium, potassium, and 

 calcium. In order to observe the effect of calcium in a more marked way, at h, another 



