METABOLISM 



10. METABOUSM OF PANTOTHENIC ACID 

 Blood Concentration 



The concentration of pantothenic acid in normal human blood was 

 stated by Stanbery et al.^ to vary from i8 to 34 /xg. per 100 ml., with 

 an average of 20 /xg, per 100 ml., and by M. J. Pelczar and J. R. Porter ^ 

 to be between 3 and 9 [xg. per 100 ml. H. Mcllwain and F. Hawking ^ 

 reported a value of 20 to 40 fig. per 100 ml. for whole human blood or 

 plasma, and values of 40 to 80 ixg. per 100 ml. for rat blood and 200 

 to 400 fjig. per 100 ml. for mouse blood. The pantothenic acid con- 

 centration of chicken blood and plasma was found to be 43-6 and 51-6 

 fxg. per 100 ml. on an adequate diet and slightly lower on a less 

 adequate diet ; * about 86 % of the pantothenic acid was present in 

 the plasma. 



Following the intravenous injection of sodium or calcium panto- 

 thenate, normal human subjects immediately began to excrete panto- 

 thenic acid in the urine, and the blood concentration rose by 50 % 

 in three hours. ^ In patients suffering from pellagra, beriberi or ribo- 

 flavine deficiency, however, the concentration in the blood decreased. 

 When pantothenic acid was injected into normal subjects the ribo- 

 flavine as well as the pantothenic acid level of the blood increased and, 

 conversely, administration of ribofiavine increased the pantothenic 

 acid, as well as the ribofiavine, concentration of the blood. R. H. 

 Silber and K. Unna ^ confirmed the rapid increase in the blood con- 

 centration that followed the intravenous injection into dogs of 4 mg. 

 per kg. of bodyweight and noted that the value fell to normal within 

 two hours. They were unable to find any change, however, in the 

 blood ribofiavine concentration following pantothenate injection or in 

 the pantothenic acid concentration following injection of ribofiavine. 

 The amount of pantothenic acid in the blood of rabbits decreased 20 

 to 30 % after administration of 5 to 10 g. of glucose. "^ Most of the 

 pantothenic acid in the blood was present in the combined form, the 

 complex being thrown down by protein precipitants.^ 



Pantothenic Acid in Tissues and Body Fluids 



The pantothenic acid contents of different human tissues varied 

 considerably, the following values being recorded by Nielsen et al. : ^ 

 muscle, 4 ; liver, 40 ; kidney, 30 ; spleen, 20 ; nerve, 3 ; pancreas, 7 ; 

 adrenals, 5 and pylorus, 10 /ag. per g. of dry matter. Free ^-alanine was 

 only found in the liver (150 ^g. per g.) and pancreas (7-5 /xg. per g.). 



According to R. H. Silber,^^ the tissues, as well as the blood, of 

 depleted dogs contained less pantothenic acid than the tissues of 

 controls dosed with the vitamin but, compared with normal dogs, 



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