A text-book of physiological chemistry : for students of medicine and physicians / by Charles E. Simon.

  • Charles Edmund Simon
Date:
1904
Catalogue details

Licence: Public Domain Mark

Credit: A text-book of physiological chemistry : for students of medicine and physicians / by Charles E. Simon. Source: Wellcome Collection.

Provider: This material has been provided by the Augustus C. Long Health Sciences Library at Columbia University and Columbia University Libraries/Information Services, through the Medical Heritage Library. The original may be consulted at the the Augustus C. Long Health Sciences Library at Columbia University and Columbia University.

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    This is, therefore, a vital or nltravital process, and there :s abundant evidence to show that this view, which is now quite generally acee])ted, is correct. Under ordinary conditions it is difficult to show that acid material is produced while the muscle is at work, as it is then removed by the circulation as rapidly as formed; but if this is prevented, the fact can readily be demonstrated. To this end, one sciatic nerve of a rabbit is divided and the animal poisoned with strychnin. If then the muscles of both legs are removed during the final convulsions of the animal, it will be noted that the reaction of those groups which had remained in connection with their nerve- supply is distinctly acid, w^hile the others, the nerve of which was severed, show a neutral reaction. Tliat the acid reaction in such cases is, in part at least, actually due to lactic acid, can be shown by extracting the rested and the tetanized groups with water and then with alcohol. On evaporating the resulting extracts and weighing the corresponding residue it will be noted that the weight of the alcoholic fraction is greater in the case of the worked muscle than of those that have rested, while the reverse holds good for the aqueous portions. Lactic acid is, however, produced by the muscle not only when at work, but also while resting. This has been shown by Zillessen and V. Frey. These observers found that on transfusing the muscles of the hindquarters of a dog, during three hours, an increase in the amount of lactic acid resulted, which, calculated for the entire amount of blood, corresponded to as much as 1.48 grammes of zinc lactate. The amount of lactic acid that may be isolated from dead muscles wdiile still rigid varies between 0.1 and 1.0 per cent., and it is note- worthy that for definite groups of muscles this amount is constant, no matter whether the formation of the acid is allowed to proceed rapidly or slowly. This, however, holds good only for correspond- ing muscles, and is different in different groups. In rabbits larger amounts can thus always be obtained from the muscles of the trunk than from those of the extremities. To the general rule that the acidity of corresponding muscles is always the same, there is one exception, viz., the heart, which is the only muscle of the body, moreover, that normally presents an acid reaction. Larger amounts of lactic acid are here always found in the left than in the right side. As regards the origin of lactic acid in muscle-tissue, it w^as long thought that the glycogen probably represented its principal source. There area number of facts indeed which favor such an assumption. I have pointed out already that after death tlie glycogen gradu- ally disappears, and we have just seen that lactic acid is then found. Glycogen is similarly decomposed during muscular activity in the living animal, where lactic acid is also constantly produced, and, as I have shown, the same also occurs in tlie muscle while at rest. Then again there is evidence to show that the decomposition of glucose in the muscle-tissue does not occur in the sense of a direct
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