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Vascular Effects of 2-Chloroprocaine and Sodium Metabisulfite on Isolated Rat Aortic Rings
  1. Michael H. Wills, M.D.,
  2. Jeffrey C. Moscicki, M.S.,
  3. Roger A. Johns, M.D.*,
  4. Cosmo A. Difazio, M.D., PH.D. and
  5. David J. Stone, M.D.
  1. From the University of Virginia School of Medicine, Department of Anesthesiology, Charlottesville, Virginia.
  2. *Recipient of the Anesthesia Young Investigator/Parker B. Francis Award.


Neurologic deficits have followed the intrathecal injection of 2-chloroprocaine 3% (10−1 M) with sodium metabisulfite 0.2% (10−2 M) as a preservative. This study evaluated the effects of varying concentrations of 2-chloroprocaine and sodium metabisulfite, as well as the combination of the two, on the vascular reactivity of isolated rings of rat thoracic aorta. Isolated Sprague-Dawley rat thoracic aortic rings were prepared and connected to force transducers for measurement of isometric tension. The tension produced by logarithmically increasing concentrations of 2-chloroprocaine, sodium metabisulfite, and their paired combination was measured. Sodium metabisulfite concentrations below 0.2% (10−2 M) caused a maximum of 40% vasoconstriction compared to control followed by vasodilation with a maximum of 80% at 10−2 M (the concentration in the former clinical preparation). 2-chloroprocaine alone produced a progressive relaxation at 10−3 M or higher concentration with a maximum of 130%. The effects of the mixture of sodium metabisulfite and 2-chloroprocaine were identical to the effects produced by 2-chloroprocaine alone. The relaxation effects of 2-chloroprocaine dominate the vasoconstricting effects of sodium metabisulfite when the two drugs are combined.

  • Local anesthetics
  • chloroprocaine
  • metabisulfite
  • toxicity
  • anesthetic techniques
  • epidural
  • complications

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