Mixing rate of phosphate between plasma and interstitial body fluid of cows

Radiophosphate was injected into the left jugular vein of dairy cows. Blood samples were taken frequently from the right jugular vein during the first hour after injection. Between 20 minutes and 1 hour after injection, the decrease in plasma radioactivity could be formulated as a first order process, designated as "process 3," with a turnover time of 50 minutes. From 5 to 20 minutes after injection the decrease in plasma activity could be interpreted as the result of mixing plasma phosphate with another phosphate pool, designated as the second pool. The capacity of this second pool was derived as a constant in a kinetic equation, so chosen that the resulting mixing rates were independent of time. For two cows the capacity of the second pool was 5 and 8 times, respectively. the phosphate content of the plasma. This result led to the working hypothesis that the major part of the second pool was the phosphate in the interstitial tissue fluid. The turnover time of the plasma phosphate in the mixing process with the second pool amounted to an average of 14 minutes for 5 lactating cows, and an average of 21 minutes for 2 dry cows. This result was obtained under the assumption that the slow first order process 3 is parallel to the mixing process. The assumption that the slower first order process is in series with the mixing process reduces the resulting mixing time to about four-fifths of that reported above. The calculation of process 2 which deviates from first order may be applicable to numerous turnover processes in which both exchange pools have a limited capacity.

Serum fractionation and the effects of bovine serum fractions on human cells grown in a chemically defined medium

Serum has been fractionated by curtain electrophoresis using carboxymethyl cellulose dissolved in sodium bicarbonate electrolyte. Various fractions were produced from bovine serum and added to replicate cultures of Chang's endoepithelial cells and HeLa cells grown in a chemically defined medium. The effects of each of the various fractions on the appearance of the cultures and on cell multiplication were studied. Three different fractions were obtained and two were subjected to further purification. One fraction associated with albumin promoted survival, attachment, and flattening as well as cell multiplication. A second fraction associated with the alpha globulins promoted survival and multiplication of some cells. A third fraction caused cells to aggregate and form free floating clumps. An adequate chemically defined medium for continuous growth of human cells was used throughout the study. The response of cells to alterations in their environment which simulated some of the effects produced by serum fractions is described.

DIFFERENCES IN THE CLOTTING OF LAMPREY FIBRINOGEN BY LAMPREY AND BOVINE THROMBINS

1. Improved methods for the purification of lamprey thrombin and fibrinogen are presented. 2. Lamprey thrombin releases two fibrinopeptides from lamprey fibrinogen during the transformation into fibrin. Bovine thrombin releases only one of these, a peptide referred to as fibrinopeptide B. The differences in the by-products of fibrin formation are reflected in the different N-terminal amino acid compositions of the two types of fibrin. 3. The fibrinopeptide that is not removed from the lamprey fibrinogen by bovine thrombin can subsequently be released by treatment of that fibrin with lamprey thrombin. 4. Under the conditions used, lamprey thrombin releases both fibrinopeptides at about the same rate. 5. The differences in interaction among these pairs of related proteins are extreme manifestations of the phenomenon loosely referred to as ;species specificity'.

THE ADENOSINE-TRIPHOSPHATASE ACTIVITY OF ADRENAL CHROMAFFIN GRANULES

1. The preparation of a fraction containing highly purified chromaffin granules from the bovine adrenal medulla is described. 2. The fraction contains an adenosine-triphosphatase activity that is stimulated by Mg(2+) and that cannot be explained by contamination with mitochondria or microsomes. 3. It is suggested that the adenosine-triphosphatase activity is related to the uptake of cate-cholamines by the chromaffin granules.

EFFECT IN THE COW OF INTRARUMINAL INFUSIONS OF VOLATILE FATTY ACIDS AND OF LACTIC ACID ON THE SECRETION OF THE COMPONENT FATTY ACIDS OF THE MILK FAT AND ON THE COMPOSITION OF BLOOD

1. The effects in the cow of intraruminal infusions of acetic acid, propionic acid or butyric acid on the secretion of the component fatty acids of the milk fat, and of these acids and of lactic acid on the composition of the blood plasma of the jugular vein, have been studied. 2. The infusion of acetic acid or butyric acid increased the yield of the C(4)-C(16) acids of milk fat but decreased the yield of C(18) acids. The infusion of propionic acid decreased the yields of all major component acids except palmitic acid and possibly lauric acid. 3. The changes in the concentrations in blood plasma of glucose and of ketone bodies were consistent with the glucogenic effect of propionic acid and the ketogenic effects of butyric acid and acetic acid. The effects of lactic acid were not consistent from cow to cow. Only with the infusion of acetic acid was a significant increase in the concentration of total volatile fatty acids in blood plasma found. Infusions of butyric acid and of propionic acid tended to depress the concentration of citric acid in the blood plasma and infusion of acetic acid increased it. No consistent effects of the infused acids on the concentration in blood plasma of esterified cholesterol, free cholesterol, triglyceride or phospholipid were observed. 4. The possibility is discussed that the effects of the infused acids on milk-fat secretion are caused through an alteration of the concentrations of precursors of milk fat in mammary arterial blood.

CONTAMINATION OF COMMERCIAL RABBIT ALBUMIN PREPARATIONS BY BOVINE ALBUMIN

Seven commercial rabbit serum albumin preparations obtainied from two different sources were found to contain bovine serum albumin. The extent of contaminiation in three representative samples varied from 0.35 to 0.54 percent.

LIPOLYTIC ACTION OF EPINEPHRINE IN ADIPOSE TISSUE HOMOGENATES

Incubation of intact adipose tissue with ACTH, certain preparations of growth hormone, and epinephrine induces an increase in lipolytic activity in homogenates prepared from this tissue. Epinephrine also causes an increase in lipolytic activity when added directly to adipose tissue homogenates. The increase is inhibited by 4 x 10–4 m iodoacetate. Mitochondrial and "supernatant" fractions (including microsomes) and the lipid layer all possess lipase activity, but only the lipase found in the supernatant fraction can be activated by epinephrine. Protamine activates this lipase; addition of epinephrine has no additive effect. Heparin inhibits the stimulation of lipase activity by epinephrine, but has no action on the lipolysis occurring in the absence of epinephrine. It is concluded that the epinephrine-stimulated lipase is distinct from lipoprotein lipase and the lipase present in unstimulated tissue.