Affiliation:
1. From the Department of Physiology, New York Medical College, Valhalla, NY.
Abstract
Background
Lactate increases lucigenin chemiluminescence (CL)–detectable superoxide anion (O
2
•
−
) generation in bovine vascular smooth muscle and endothelium, and a microsomal flavoprotein-containing NADH oxidase whose activity is regulated by P
o
2
and cytosolic NAD(H) redox appears to be the detected source of O
2
•
−
production. Little is known about the importance of this O
2
•
−
-producing system in cardiac myocytes.
Methods and Results
In isolated bovine cardiac myocytes, lactate (10 mmol/L) increased lucigenin-detectable O
2
•
−
levels to ≈1.8 times baseline, whereas pyruvate (10 mmol/L) and mitochondrial probes did not increase the detection of O
2
•
−
. A nonmitochondrial NADH oxidase activity, found in microsomes containing a cytochrome
b
558
, was a major source of O
2
•
−
production in the homogenate of myocytes, because NADH (0.1 mmol/L) increased basal lucigenin CL >100-fold. NADPH oxidases, mitochondria, and xanthine oxidase were minor sources of detectable O
2
•
−
production. However, mitochondria released H
2
O
2
in the presence of 5 mmol/L succinate and 30 μmol/L antimycin, based on its detection as catalase-inhibitable luminol (+horseradish peroxidase)–elicited CL. Diphenyliodonium (DPI), an inhibitor of flavoprotein-containing oxidases, significantly attenuated basal, lactate, and NADH-elicited lucigenin CL. Hypoxia eliminated myocyte lucigenin CL, and posthypoxic reoxygenation caused an 8.6-fold increase in the detection of O
2
•
−
that was potentiated by lactate and inhibited by DPI.
Conclusions
NADH oxidase activity linked to cytosolic NAD(H) redox appears to be a key source of O
2
•
−
production in cardiac myocytes that could contribute to oxidant signaling mechanisms and injury upon exposure to changes in P
o
2
and metabolites produced under hypoxia, such as lactate. These processes could contribute to the previously observed potentiation of injury caused by lactate in cardiac ischemia/reperfusion.
Publisher
Ovid Technologies (Wolters Kluwer Health)
Subject
Physiology (medical),Cardiology and Cardiovascular Medicine
Cited by
107 articles.
订阅此论文施引文献
订阅此论文施引文献，注册后可以免费订阅5篇论文的施引文献，订阅后可以查看论文全部施引文献