Trichloroacetic Acid-soluble Fraction Research Articles

Occurrence of Radioactivity in the Protein Fraction and in the Trichloroacetic Acid Soluble Fraction of Pancreas after Intravenous Injection of S35 ‐DL‐Methionine

Occurrence of Radioactivity in the Protein Fraction and in the Trichloroacetic Acid Soluble Fraction of Pancreas after Intravenous Injection of S³⁵ ‐DL‐Methionine

Distribution of glycogen in the rat heart.

The total and trichloroacetic acid soluble fractions of glycogen were determined in various portions of the rat heart. The amount in each portion was compared on the basis of the nitrogen content of the same sample. The total glycogen concentration was highest in the atria, lowest in the left ventricle and intermediate in the septum and right ventricle. A similar distribution was found for TCA soluble glycogen. The possible role of glycogen in cardiac energetics and structure is discussed.

Effect of digoxin on cardiac glycogen of the rat.

SummaryDigoxin in a dose of 0.2 mg/ kg caused either no change or a slight increase in the cardiac glycogen fractions when administered to rats of 30 days of age or less, but caused a decrease in all fractions of cardiac glycogen when given to rats of 100 and 360 days of age. At 630 days of age, digoxin caused a fall in the trichloroacetic acid soluble fraction and an increase in the acid insoluble fraction with no change in total cardiac glycogen. When administered to 100- and 360-day-old rats toxic doses of digoxin increased all fractions of cardiac glycogen except the acid soluble fraction of the 100-day-old rats which showed no change.

Effect of hormones on the trichloracetic acid extractable glycogen in skeletal muscles.

COLD 10% trichloroacetic acid (TCA) removes from homogenized liver and muscle tissue respectively, a relatively constant amount of glycogen, somewhat less than the total amount present as determined by the usual hot alkali method of extraction (Bloom et al., 1951). Whenever glycogenolytic agents (epinephrine, nerve stimulation) reduce the glycogen in muscle tissue, it is the TCA extractable fraction which decreases markedly (Bloom and Knowlton, 1953). These investigators attribute a “labile” quality to the TCA soluble fraction, in contrast to the more resistant “residual” glycogen fraction which is relatively unaffected after mild stimulation of these tissues by glycogenolytic agents. Since both cortisone and growth hormone vary in their ability to influence glycogen deposition in different muscles (Leonard, 1953) and in their ability to inhibit the glycogenolytic action of epinephrine (Wortman and Leonard, 1953; Leonard and Ringler, 1954), a possible explanation of these phenomena was sought in a study o...

THE ACCUMULATION OF PHOSPHATE BY FERTILIZED SEA URCHIN EGGS

1. The concentration of phosphate in the external medium of a suspension of unfertilized Strongylocentrotus eggs remains constant, or increases, while in a suspension of fertilized eggs, the concentration of phosphate in the external medium decreases.2. Fertilized Strongylocentrotus eggs absorb P32 and phosphate from sea water at identical rates, revealing that the exchange of phosphate between the cell interior and the external medium is inappreciable.3. The rate at which phosphate is removed from sea water by fertilized Strongylocentrotus eggs is relatively independent of the external concentration as long as this exceeds 15 to 20 micrograms P per liter.4. When unfertilized and fertilized sea urchin eggs are continuously exposed to sea water containing P32 and more than 20 micrograms P per liter, 95.9 to 96.4 per cent of the P32 which enters the eggs is found in the trichloroacetic acid-soluble fraction, with 3.6 to 4.1 per cent of the P32 being recovered in the acid-insoluble fraction. The distribution of P32 between these two fractions is not significantly different in the unfertilized, as compared to the fertilized eggs. Although a slightly lower proportion of P32 was found in the acid-insoluble residue of unfertilized eggs, outward leaching of P32 during the washing of the unfertilized eggs may well account for the difference noted.5. If fertilized Lytechinus pictus eggs containing P32 are suspended in a non-radioactive medium shortly after insemination, the proportion of P32 in the acid-insoluble fraction increases from 3.6 per cent at the two-celled stage to 7.0 per cent at the blastula stage.6. The concentration of inorganic P in the trichloroacetic acid-soluble extracts of the eggs decreases prominently following insemination. A corresponding increase occurs in the quantity of P liberated after 10 minutes' hydrolysis of the extracts in 1 N HCl at 100° C.7. The major portion of the P32 which enters the eggs is found in the easily hydrolyzable P fraction of the trichloroacetic acid-soluble extracts. After fertilization, the proportion of P32 in the easily hydrolyzable P fraction increases.