Figure 3. Steady-state hypoxic ventilatory response curves during control (solid square) and after administration of morphine (delta) of one cat. The drawn lines are the exponentials fitted to the data according to the function V with dotI= G.exp(-D.PETO2)+ A, with G = 1.807 l/min, D = 0.0204 mmHg sup -1, and A = 1.032 l/min for control and G = 2.697 l/min, D = 0.0291 mmHg sup -1, and A = 0.474 l/min for morphine.