PT  - JOURNAL ARTICLE
AU  - Michael H. Wills
AU  - Jeffrey C. Moscicki
AU  - Roger A. Johns
AU  - Cosmo A. Difazio
AU  - David J. Stone
TI  - Vascular Effects of 2-Chloroprocaine and Sodium Metabisulfite on Isolated Rat Aortic Rings
AID  - 10.1136/rapm-00115550-198914060-00003
DP  - 1989 Nov 01
TA  - Regional Anesthesia: The Journal of Neural Blockade in Obstetrics, Surgery, & Pain Control
PG  - 271--273
VI  - 14
IP  - 6
4099  - http://rapm.bmj.com/content/14/6/271.short
4100  - http://rapm.bmj.com/content/14/6/271.full
SO  - Reg Anesth Pain Med1989 Nov 01; 14
AB  - 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.