How did Claude Bernard use curare to distinguish nerve and muscle mechanisms?

The 19th-century French physiologist Claude Bernard utilized curare as a precise experimental tool to distinguish between nerve and muscle mechanisms. By observing the effects of this poison on the body, he demonstrated that curare induces paralysis by specifically attacking motor nerves at the neuromuscular junction—the site of communication between nerve and muscle fibers.12

Bernard’s experiments revealed that curare blocks the transmission of impulses between these two systems without directly affecting nerve conduction or the inherent ability of the muscle to contract. Because of this selectivity, he was able to differentiate neuromuscular transmission from primary muscular mechanisms, proving that the paralysis was not caused by a failure of the muscles themselves or the nerves' ability to conduct signals, but rather by the disruption of the connection between them. This work was foundational in establishing the physiological understanding of how skeletal muscle responds to electrical impulses.21