Transport of Alanine, Arginine and Glutamic Acid in the Rabbit Erythrocyte and Reticulocyte.

Abstract

645the two tissues. High pyruvate concentrations inhibit LDH activity from either source to the same extent. The degree of inhibition by urea is always significantly less (p<.OO5) at the high (1 X M ) than at the low ( 5 X M) pyruvate level. Oxalate inhibits inguinal adipose tissue LDH less at the high than a t the low pyruvate level, while showing a reverse effect on the enzyme from pericardial tissue. Michaelis-Menten constants (K&I) for pyruvate were calculated from activities both in the absence and in the presence of urea and oxalate. KII values were significantly decreased in the presence of 2.0 M urea. All levels of oxalate studied increased the KM of pericardial adipose tissue LDH, but did not affect that of the inguinal adipose tissue enzyme, Incubation at 59°C for 10 minutes inactivates both enzymes to about the same extent, leading to a loss of 44 and 47% of their activity , respectively . Electrophoretic separation revealed 5 isozymes with a higher proportion of fast moving subunits in pericardial adipose tissue LDR.It gives the author pleasure to acknowlredge the skillful technical assistance of Miss Gail Crane.

Arginine Metabolism in the Blood Cells of Cattle and Goats

“…After incubation with 14C arginine, no 14C ornithine was found in goat blood. The possible role of blood cells in urea production is discussed.Little is known about the role of blood cells in nitrogen metabolism in animals.Yunis and Arimura [1965] and Rohrs and Archdeacon [1967] investigated the passage of aminoacids through the erythrocyte membrane. Human erythrocytes contain transaminases [Mircevova, Jirgl and Vosykova, 1960] and arginase [Reynolds, Follete and Valentine, 1957].…”