Abstract

Reduced glutathione produced a marked lowering of the threshold of irritability of the cat papillary muscle but did not change contractile force. On the other hand, methionine did not change irritability but increased contractile force. Cysteine lowered the threshold of irritability and increased contractile force. These findings suggest that different metabolic cycles may be involved in furnishing energy for the various aspects of cardiac muscle function. Reduced glutathione may prove useful in some cases of diminished ventricular irritability.