Figure 6. Heart rate and mean arterial blood pressure during 30 days of exposure to 6% InCO₂ or room air.

Heart rate increased during initial exposure to 6% InCO₂ (A) and remained ∼10 beats/min above control throughout 30 days of chronic hypercapnia (A). Similarly, mean arterial blood pressure increased by ∼10 mmHg during the first week of hypercapnia, and remained elevated thereafter (B). Minimal changes were noted in either heart rate or mean arterial blood pressure during 30 days of room air exposure (C, D). The solid lines provide a reference to control values obtained at room air prior to 30 days of 6% InCO₂ or room air exposure. P values shown were derived from a one‐way repeated measures ANOVA (time as factor).