The Significance of Respiratory Chain Oxidations 635 



Both substances appeared to increase the amount of glucose metabohzed by 

 the gland by way of the oxidative steps of the pentose phosphate pathway 

 and it is suggested that this occurred by an increased rate of reoxidation of 

 TPNH, either by electron transport via the phenazine compound, or by the 

 increased reductive lipogenesis in the case of insulin. It will be recalled that 

 insulin has a closely similar effect in increasing the C-1 oxidative decarb- 

 oxylation of glucose in adipose tissue; so marked is this effect that it has been 

 made the basis of an extremely sensitive assay method for the determination 

 of levels of insuhn in human blood by Martin, Renold and Dagenais (1958). 

 Recently Ball, Martin and Cooper (1959) have confirmed these results and 

 found a graded response on the CO^ output between 10"^ to 10"^ units of 

 insulin per ml (normal serum averages 10^ units of insulin per ml). These 

 authors attribute the large release of extra COg to the synthesis of fat from 

 glucose, coupled with increased activity of the oxidative pentose cycle, as 

 described above. 



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