Calcium or magnesium concentration affects the severity of organophosphate-induced neuromuscular block.

When the rat diaphragm muscle was treated with düsopropyl fluorophosphate, an organophosphate inhibitor of acetylcholinesterase, a decrement in the compound action potential and in the force of contraction was observed. It was found that the decrement produced by 30 Hz nerve stimulation for 1 s could be reversed by lowering the calcium concentration or increasing the magnesium concentration.