A Method for the Determination of Small Amounts of Lactic Acid

Hartree and A. V. Hill (1) have shown in the isolated frog’s muscle that the maximum rate of the recovery heat-production is proportional to the square of the total initial heat liberated by the stimulus. This relation has been amply confirmed by Hartree, in experiments hitherto unpublished on the isolated muscle of the tortoise. Hartree and Hill concluded that the speed of the recovery oxidation is at any moment proportional to the square of the concentration of the reacting bodies present at that moment, and suggested that a bimolecular reaction of some kind, possibly involving two lactic acid molecules, might be the determining agent in the velocity of the recovery oxidation. Up to the present it has not been shown that any substances other than lactic acid and oxygen are directly concerned in the recovery process in muscle, so the above relationship can be put in terms of these substances. Expressed in a formula, (rate of oxidation) ∝ (rate of lactic acid removal) = k (concentration of lactic acid) 2 , where k is a velocity constant. In a recent paper Meyerhof, Lohmann and Meier (2) have shown that isolated frog’s muscle perfused by, or suspended in, an oxygenated Ringer’s solution containing sodium lactate will cause a diminution in the amount of lactate in the perfusing fluid, with an uptake of oxygen and a synthesis of glycogen. In these experiments it was obvious that the lactate ion was the determining factor in exciting the oxidation by which the energy was supplied to effect the synthesis of the glycogen. Moreover, as Hartree and Hill have shown (3), a rise of hydrogen ion concentration alone does not increase, but rather decreases, the speed of the recovery process in muscle. It seemed obvious, therefore, that the lactate ion itself was to be regarded as the governing factor in the speed of oxidation.

“…Immediately after this the second blood sample was taken. The lactic acid was estimated by Clausen's method (6).…”

Section: Methodsmentioning

confidence: 99%

Muscular exercise, lactic acid, and the supply and utilisation of oxygen.—Part XIV. The relation in man between the oxygen intake during exercise and the lactic acid content of the muscles

1926

“…The method used throughout has been that detailed by Clausen (6). The proteins were first precipitated by the use of tungstic acid (Folin and Wu (26)).…”

Section: Estimation Of Lactic Acid In Bloodmentioning

confidence: 99%

“…is the extraction with ether. Clausen (6) details an apparatus for continuous extraction which I have tried, but which requires careful handling for its proper working. Another point to be noted is that the ether used for the extraction must be carefully purified : otherwise the impurities present yield bisulphite binding compounds when oxidised.…”

Section: Lactic Acid Inmentioning

confidence: 99%

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Muscular exercise, lactic acid, and the supply and utilisation of oxygen.—Parts ӏ-ӏӏӏ

Hill

Long

Lupton

1924

239

In a recent paper under the general title of this series A. V. Hill and Lupton (1) gave a preliminary account of experiments made on man, in an attempt to press to its logical conclusion the physico-chemical view of muscular contraction arrived at by the investigation of the isolated muscle. The present series of papers contains a more adequate account of these experiments, which are still in progress. ( a ) The “ Initial ” Process . In the isolated muscle the complete cycle of contraction and relaxation, as distinguished from recovery, appears to be accompanied by no chemical change of any importance, other than the conversion of glycogen into lactic acid, and the subsequent neutralisation of the latter (2) (4). These “ initial ” phases of muscular activity are entirely non-oxidative in character (3), and the following “ balance sheet ” (Table I) shows that, if any other chemical changes do actually occur, they are negligible from the energy standpoint.

“…permitting frequent samples to be taken by pricking the lobule of the ear. For lactic acid estimations by Clausen's method (6) blood was withdrawn from the median basilic vein, as also for the estimation of acetone bodies by Shaffer's (7) and van Slyke's (8) methods. These blood samples were taken before exercise, immediately after exercise, and at the end of recovery.…”

Section: Introductionmentioning

confidence: 99%

The metabolism of the diabetic individual during and after muscular exercise

1926

The work of Hill, Long and Lupton (1) on the effects of muscular exercise in normal men, and more recently that of Furusawa (2) on the carbohydrate metabolism during exercise, made it desirable to undertake a similar investigation of the reactions to exercise of a diabetic individual with his deficient power of utilizing carbohydrates. Furusawa’s results show that in normal men on an ordinary diet the respiratory quotient of the excess metabolism due to exercise is unity, for periods of moderate exercise up to about 20 minutes. For similar exercise of longer duration the respiratory quotient of the excess metabolism is lower. When the subject had been living for some time previous to the experiment on a diet consisting chiefly of fat, the respiratory quotient of the excess metabolism was still unity for exercise of very short duration, but fell below unity for efforts of much shorter duration than 20 minutes. In the diabetic the carbohydrate reserves are less than in a healthy man, and his diet is restricted as regards carbohydrate and contains an excess of fat to make up the requisite number of calories. The diabetic, therefore, under such conditions, might be expected to approximate, in regard to exercise, to a healthy man living on a diet largely composed of fat. In the present investigation the effect of muscular exercise has been studied in three diabetic patients on lines similar, to those adopted by the above authors. We hoped that by exercising these patients with and without injections of insulin, some conception might be formed of the rôle of insulin in the metabolic processes involved in muscle during and after exercise. Recent work by Himwich, Loebel and Barr (3), and by Doisey, Briggs, Weber and Koechig (4), has shown that in the diabetic animal the formation of lactic acid from the glycogen of muscle on exercise is independent of the presence of insulin. Our results on diabetic patients confirm this view. We desired also to ascertain the likelihood of the development of ketosis and diabetic coma as the result of exercise in diabetics, together with the modifications which insulin might have on this process; further, there was the question of restriction of exercise in such patients, if it acted deleteriously. We attempted, moreover, to obtain information as to whether the dosage of insulin required depended on the amount of muscular work which the individual undertook, and also as to the need for regulation of exercise after a patient had been discharged from the inactive life in hospital.