Relation Between Thiamine and Co-Carboxylase Concentration and Work Output of Perfused Frog Muscles. ∗

Abstract

Summary

The work output of the gastrocnemius muscle of the perfused frog has been determined at different levels of thiamine concentration in the perfusion fluid. The effects on the work output of adding thiamine pyrophosphate (co-carboxylase) and thiamine hydrochloride to the perfusion fluid has been compared. 1. The addition of thiamine hydrochloride to the perfusion fluid improved the work output of frog muscles. The degree of improvement increased with increasing concentrations of hydrochloride from 0.0001 to 0.001 mM per liter. 2. No further improvement in work output resulted when thiamine hydrochloride concentration was increased to 0.1 mM per liter. 3. Increasing the thiamine concentration of the perfusion fluid from 0.1 to 1.5 mM per liter progressively reduced the improvement in work output. 4. Thiamine pyrophosphate was also effective in increasing the work output in perfused frog muscles. 5. Thiamine pyrophosphate increased the work output at lower concentrations than did thiamine hydrochloride. 6. At concentrations of 0.001 mM per liter or above, the extent of the improvement in work output was no greater with thiamine pyrophosphate than with thiamine hydrochloride.