Recent advances in endocrinology / by A.T. Cameron.

  • Alexander Thomas Cameron
Date:
1933
Catalogue details

Licence: In copyright

Credit: Recent advances in endocrinology / by A.T. Cameron. Source: Wellcome Collection.

    154/402 (page 140)
    liver glycogen formation, or retards it, or even reverses the action (52, 17, 145, 107). Cori’s experiments on rats suggest that under insulin action muscle tissue absorbs glucose so rapidly that none is available for liver glycogen formation, while blood sugar concentration also is a determining factor (37). Perhaps, however, the most important factor is the concentration of insulin itself. It has been shown that in starved rabbits, in which the liver glycogen had fallen to less than 0-2 per cent., injection of insulin in amounts insufficient to cause convulsions definitely increased liver glycogen (in eleven experiments the glycogen content varied from 0-6 to 3-8 per cent.). Similar results were obtained with dogs, using small doses of insulin. Larger (convulsive) doses caused disappearance of glycogen from the liver (54). It seems reasonable to assume, in spite of the contradictory nature of much of the experimental evidence, that under physiological conditions one of the most important actions of insulin is the facilitation of glycogen formation from glucose in both liver and muscle tissue. Whether this is the sole action, or whether insulin also facilitates direct oxidation of glucose, cannot be stated. If the latter be not the case, it obviously follows that glucose, to be oxidized, must be first transformed to glycogen. It has been conclusively demonstrated that when ordinary commercial preparations of insulin are injected intravenously into animals a distinct hyperglycaemia is produced within a few minutes, which subsequently gives place to the hypo- glycaemia usually associated with insulin injection (24, 85). This anomalous effect is not produced by crystalline insulin, and must therefore be attributed to impurities in the com¬ mercial insulin preparations (60). Extracts of pancreas have been shown to produce hyperglycaemia when injected intravenously (114, 62), and the effect, when produced bv insulin preparations, is probably due to traces of proteoses and peptones. With this illustration in mind the following comment (85)