Figure 1. Time course of nerve stimulation in the two extremities is shown for phases 2–4. Train-of-four stimulation was initiated in one extremity at -20 (i.e., 20 min before drug was administered), and supramaximal response was established in 0.6–1 min. At -2 min, train-of-four stimulation was initiated in the second extremity preceded by no tetanus (phase 2), a 2-s tetanus (phase 3), or a 5-s tetanus (phase 4); immediately thereafter, a supramaximal response was attained. Vecuronium, 30 micro gram/kg, was given at time 0.