Studies in neuromuscular transmission. IV. Influence of changes in blood pH and carbon dioxide tension on the effect of succinylcholine.

Gamstorp, I. and E. Vinnars. Studies in neuromuscular transmission IV. Influence of changes in blood pH and carbon dioxide tension on the effect of succinylcholine. Acta physiol. scand. 1963. 58. 48—56. — The influence of changes in the arterial blood pH and the partial pressure of carbon dioxide on the effect of succinylcholine was investigated in rabbits. The sciatic nerve was stimulated supramaximally and the electric response of the gastrocnemius muscle was recorded; the amplitude of the response was used as a measure of the severity of the block. Tachyphylaxis was noted on administration of repeated, small doses of succinylcholine but no changes referable to the shift in pH or pCO2. Changes in pH or pCO2 had no demonstrable effect on the block caused by a single, large dose of succinylcholine. The block caused by a continuous infusion of succinylcholine was enhanced by severe respiratory acidosis. It was not significantly influenced by mild respiratory acidosis, respiratory alkalosis, metabolic acidosis or alkalosis, or infusion of adrenaline. The possibility of these findings being due to a slower hydrolysis of succinylcholine and acetylcholine at a high pCO2 is discussed.