How did Claude Bernard explain curare’s ability to cause paralysis?

Claude Bernard, a 19th-century French physiologist, conducted pioneering research on curare that helped establish the field of experimental physiology. Through his experiments, he demonstrated that curare causes paralysis by specifically blocking the transmission of impulses between motor nerves and muscles.12

Bernard’s work was significant because he proved that the poison does not directly affect the nerves themselves (nerve conduction) or the muscles themselves (muscle contraction). Instead, he showed that curare acts selectively on the motor nerves, leaving sensory nerves unaffected. By identifying this specific site of action, Bernard utilized curare as an experimental tool to differentiate between neuromuscular and primary muscular mechanisms. This analysis was among the first to explain the physiological action of a drug in such precise, mechanistic terms.12