The Respiration and Energy Metabolism of Sheep Lymphocytes

Abstract

Summary The respiration characteristics and energy metabolism of sheep lymphocytes collected from the popliteal lymph before and after antigenic challenge with Salmonella organisms have been studied at various O2 tensions. The O2 consumption of sheep lymphocytes could be related to the PO2 of the medium by the Michaelis‐Menten equation. In resting lymphocytes, Vmax (mean ± S.D.) was 1·70 ± 0·23 μmoles/h/2 × 108 cells), critical O2 concentration ([O2]crit) was 2·00 ± 0·20 μM and Km was 0·46 ± 0·11 μM. Significant chances occurred in the respiration characteristics of these cells following antigenic challenge of the nude. Both Vmax and Km reached maxima when the blast cell response in the lymph was at its peak. [O2]crit, however, did not change significantly over an immune response. Lymphocytes collected before antigenic challenge had mean rates of glucose uptake of 0·97 ± 0·29 μmoles/h/2 × 108 cells and lactate production of 1·31 ± 0·37 μmoles/h/2 × 108 cells. During the height of immune responses to Salmonella, lymphocytes showed an enhanced glucose uptake, lactate production and C‐1‐ and C‐6‐labelled glucose metabolism. The rates of energy metabolism of sheep lymphocytes varied with changes in the PO2 of the gas phase from 21% to 0% O2. The rates of glucose uptake and lactate production increased while the rates of 14CO2 production from C‐1‐ and C‐6‐labelled glucose decreased as the PO2 decreased.

Effects of pH‐variations on the kinetics of growth and energy metabolism in cultured T‐lymphoma cells: A microcalorimetric study

“…A critical oxygen concentration of 0.02 mmolil has been observed for the present cell line (Backman and Wadso, 1991). This is in agreement with critical oxygen concentrations observed for, e.g., hepatocytes (0.01-0.02 mmolil), (Jones and Mason, 1978) and sheep lymphocytes (0.0002-0.02 mmolil), (Cheung and Morris, 1984). Apparent Michaelis-Menten constants for intact cells (e.g., Jones and Mason, 1978) are typically 10 times higher than for isolated mitochondria (Jones and Mason, 1978;Cole et al, 1982;Sugano et al, 1974) which is explained by intracellular diffusion gradients, presumably due to clustering of mitochondria (Jones, 1986).…”

Six costs of immunity to gastrointestinal nematode infections

“…Metabolic requirements of leucocytes also increase when these cells are activated. Oxygen consumption, glucose utilization and glutamine utilization increase two‐ to threefold on a per cell basis (21,22). However, fever may not be a prominent feature of most GIN infections.…”

British Society for Matrix Biology Autumn Meeting Joint with the UK Tissue & Cell Engineering Society, University of Bristol, UK

“…Results Oxygen consumption and lactate production rates as a function of concentration were highly nonlinear and appeared to follow Michaelis-Menten kinetics, with rates falling steeply with fall in concentration as seen for other tissues (Cheung & Morris 1984). We confirmed that the chondrocytes demonstrated a negative Pasteur effect (Lee & Urban 1997) (i.e., inhibition of glycolysis under low oxygen) and a Crabtree effect (stimulation of oxygen consumption under low glucose) (Otte 1991), as described by others previously.…”