Figure 4. Effect of halothane dose on inspiratory duration T^I(upper) and expiratory duration T^E(lower) for control (solid bars) and stimulated carbon dioxide bolus breaths (hatched bars) in 11 animals (protocol 1). Asterisks indicate significant increases in T^Iduring the carbon dioxide stimulus and decreases of T^Eduring the test cycle compared with the respective control cycle (**P < 0.01;***P < 0.001). (section), Significant difference of the control cycle durations compared with the 1 MAC control cycle ((section)P < 0.05, (section, section)P <0.01, (section, section, section)P < 0.001). 1.0 EC: 1 MAC end-control data obtained at the end of the protocol normalized to the first 1 MAC control values.