Redox state of free nicotinamide-adenine nucleotides in the cytoplasm and mitochondria of alveolar macrophages.
J Clin Invest 1971 Jun; 50(6):1181-1186
The redox state of free nicotinamide adenine nucleotides in the cytoplasm and mitochondria of alveolar macrophages was studied in- vitro. Alveolar macrophages obtained from rabbits by pulmonary lavage were incubated with lactate and pyruvate or beta- hydroxybutyrate (BOHBu) and acetoacetate under aerobic or hypoxic conditions or under hypoxic conditions followed by aerobic conditions. The extent of conversion of lactate to pyruvate and BOHBu to acetoacetate was determined. The cytoplasmic nicotinamide- adenine-dinucleotide/reduced-nicotinamide-adenine-dinucleotide (NAD+/NADH) ratio was calculated from the lactate pyruvate conversion data and the mitochondrial NAD+/NADH ratio from the BOHBu acetoacetate data. The cytoplasmic and mitochondrial NAD+/NADH ratios in resting alveolar macrophages were 709 and 33.2, respectively. The difference was statistically significant. The cytoplasmic and mitochondrial NAD+/NADH ratios after 30 minutes of incubation in air were 455 and 10.1, respectively. The decrease in cytoplasmic NAD+/NADH ratio resulting from aerobic incubation was not significant, whereas the decrease in the mitochondrial ratio was significant. Incubation under hypoxic conditions significantly decreased both the cytoplasmic and mitochondrial NAD+/NADH ratios. During the incubation, the pH of the medium decreased from 6.3 to 5.3. A similar response was seen for cytoplasmic NAD+/NADH when the incubation was conducted under hypoxic conditions with the pH tightly controlled, varying only from 7.02 to 6.94. Hypoxic incubation followed by aerobic incubation resulted in a significant recovery of the cytoplasmic NAD+/NADH ratio toward the normal value; the mitochondrial NAD+/NADH ratio showed no such recovery. The authors conclude that separate pools of cytoplasmic and mitochondrial NAD+ and NADH exist in alveolar macrophages. Changes in redox state are at least partially independent of changes in extracellular pH. The NAD+/NADH ratio can be used as a marker for cellular abnormalities.
NIOSH-Publication; NIOSH-Grant; Grants-other; In-vitro-studies; Lung-cells; Physiological-chemistry; Oxidation-reduction-reactions; Cellular-function; Biochemical-indicators
Physiology Stanford University Sch of Med Department of Medicine Palo Alto, Calif
Other Occupational Concerns; Grants-other
Journal of Clinical Investigation
Stanford University, Stanford, California