Vascular effects of 2-chloroprocaine and sodium metabisulfite on isolated rat aortic rings.
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 log-arithmically 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.
Wills
M H
MH
Department of Anesthesiology, University of Virginia School of Medicine, Charlottesville 22908.
Johns
R A
RA
Stone
D J
DJ
Moscicki
J C
JC
Difazio
C A
CA
D000779:Anesthetics, Local / Q000494:pharmacology*; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects* / Q000502:physiology; D066298:In Vitro Techniques; D008297:Male; D011310:Preservatives, Pharmaceutical / Q000494:pharmacology*; D011343:Procaine / Q000031:analogs & derivatives* / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013447:Sulfites / Q000494:pharmacology*; D014661:Vasoconstriction / Q000187:drug effects; D014664:Vasodilation / Q000187:drug effects
D000779:Anesthetics, Local; D011310:Preservatives, Pharmaceutical; D013447:Sulfites; C005200:sodium metabisulfite; D011343:Procaine; C004616:chloroprocaine