OSMOTIC AND IONIC REGULATION 241 



in Homarus muscle, and Kermack et al. (1955) rather more since they 

 included taurine, not determined by the former workers. Proline, glycine, 

 and taurine are the most abundant, followed by glutamine, valine, arginine, 

 and alanine. Trimethylamine oxide and betaine were found by Kermack 

 et al. in considerable quantities, and also a small amount of volatile base. 

 All these substances must contribute to the osmotic concentration of lob- 

 ster muscle. Approximate concentrations in mM/kg. were : amino-acids 

 221-285, mean 256, trimethylamine oxide 75, betaine 67, volatile base 8, 

 total about 406. 



TABLE 5. COMPOSITION OF NEPHROPS AIUSCLE 



mg. ions (mM) /kg. H.O mE/kg. H^O 



Sodium 83.2 83.2 



Potassium 166.6 166.6 



Calcium 5.2 10.4 



Magnesium 19.1 38.2 



Chloride 109.9 109.9 



Sulphate 3.1 6.1 



Bicarbonate 2.2 2.2 



Inorganic phosphate 19.1 30.8*-21.5 



Arginine phosphate 74.2 76.4*-74.2 



Adenosine triphosphate 12.1 44.8*-38.7 



Remaining acid-soluble P, 



mostly hexose monophosphate 15.1 29.3*-21.7 



Lactatet 7.8 7.8 



Total cations 274.1 298.4 



Total anions 243.5 307.3*-282.1 



Amino acids 496.0 



Trimethylamine oxide 72.0 



Total mg. ionst 1,085.6 



Plasma 1,100.0 



Sea water 1,094.0 



* Assuming intracellular pH of 7.0 ; second figure pH 6.0. 

 fBoyland (1928) iov Homarus. 



t If concentration of betaine is as high as 90 mAI, found by Kermack et al. (1955) 

 in Homarus, total concentration would be 1,176 mg. ions/kg. water. 



An analysis of the muscle of Ncphrops norvcgicus, the Norway lobster, 

 is shown in Table 5 (Robertson, unpublished). The organic phosphate 

 compounds make up half the total anions and over 10% of the osmotic 

 concentration. Amino acids account for nearly half the concentration, and 

 trimethylamine oxide for about 7%. If betaine is present in the concentra- 

 tions found by Kermack et al. in Homarus, about 90 mM per kg. water, 

 the total concentration would exceed that of the plasma by 7%. It w^ould 

 be premature to discuss the inference that some of the base and perhaps 

 some of the phosphate must be bound until the concentration of betaine is 

 determined. It is almost certain, however, that most of the intracellular 

 calcium and magnesium is in the form of unionized complexes. 



