The biological lifetime of nitric oxide: Implications for the perivascular dynamics of NO and O2

We report here studies designed to estimate the lifetime of NO in the parenchymal tissue and describe the implications of these results for the distribution of NO and oxygen concentration gradients away from the blood vessel

D. D. Thomas; X. Liu; S. P. Kantrow; J. R. Lancaster


Scholarcy highlights

  • Departments of *Pathology, §Physiology, and ‡Medicine, Louisiana State University Health Sciences Center, New Orleans, LA 70112; and †The EPR Center, Johns Hopkins Medical Institutions, 5501 Hopkins Bayview Circle, Baltimore, MD 21224
  • We characterize NO consumption by parenchymal cells and present the implications of these results in terms of the concentration gradients of NO and of O2 away from a blood vessel
  • The consumption rate of NO by cells is many fold greater than the autoxidation rate, even considering the acceleration caused by hydrophobic partitioning in membranes
  • NO could react with O2 to yield nitrosyldioxyl radical, the presumed first step in the autoxidation reaction
  • It is possible that a nucleophilic species may compete with NO for reaction with ONOO1⁄7, producing the overall second-order kinetics
  • We suggested that the reaction with intact erythrocytes is limited by the rate at which NO enters the cell, which has been supported by subsequent studies
  • Additional ramifications of this coupling of the perivascular diffusion of NO and O2 include dramatically increased tissue respiration under conditions of increased parenchymal cell work and increased overlap of zones of effective oxygenation with adjacent vessels, further amplifying these effects under in vivo conditions, where vessels are not isolated from each other

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