52 ABSORPTION AND RETENTION OF POTASSIUM 



water. We hoped to avoid this effect and produce more nearly 

 physiological conditions by the use of gum arable in the perfusion 

 solution, employing, in short, a modified Bayliss solution. Gum 

 arable, purified by six alcohol precipitations from dilute hydrochloric 

 acid solution, and showing by analysis an amount of potassium less 

 than 0.01 percent was used. The solution contained the following : 



NaCl 6.5 gm. 



CaClj 0.25 " 



NaHCO, 0.20 " 



Gum arabic 45 " 



Phenol-sulphonephthalein a few drops. 



Water 1 liter. 



It had apH of approximately 7.3; 700 cc. of the solution were per- 

 fused in 6f hours through both legs. The muscles of the left leg were 

 stimulated through the lumbar plexus with maximal tetanizing induc- 

 tion shocks lasting 1 second each, given by an automatic stimulator at 

 30 second intervals during the first half of each hour with half hour 

 rest periods intervening. These muscles, then, made 360 contractions 

 lasting 1 second each. The muscles of both legs showed, at the end 

 of the experiment, good though not equal irritability. The average 

 potassium content of the muscles of the stimulated leg was 0.229 per 

 cent, of the muscles of the other leg, 0.228 per cent. Both of these 

 figures are lower than the percentages of potassium found in normal 

 frog muscle. Both legs showed, however, some swelling in spite 

 of the gum arabic. To determine the effect of contraction on the 

 potassium content it seemed necessary to compute it in relation 

 to the solids of the muscle. A further experiment for this purpose 

 was undertaken. 900 cc. of potassium-free Ringer solution were 

 perfused through both legs in 8| hours. Gum arabic because of the 

 labor involved in making it potassium-free was not used. The muscles 

 of one leg, stimulated by the method described for the preceding 

 experiment, gave 480 contractions, of 1 second each. The muscles of 

 both legs showed good irritability at the end of the experiment. The 

 average potassium content of the muscles of the stimulated leg was 

 0.203 per cent, of the muscles of the other leg, 0.230 per cent, but 

 computed as percentages of the solids: 1.86 per cent for the former 

 and 1.85 per cent for the latter. No especial loss of potassium due to 

 stimulation was shown. 



