Mode of toxicity of barium 1. Hypokalaemia and neuromuscular blockade: The rapid onset of the marked hypokalaemia so characteristic of barium intoxication is due to sequestering of potassium by muscle cells. Barium clogs the exit channel for potassium ions in skeletal muscle cells. 2. Barium stimulates striated, smooth, and cardiac muscle resulting in violent peristalsis, aerial hypeension and arrhythmias.