(A) Traces of blood pressure and ECG activity from control and P2Y2 cKO mice. (B) Summary data (N = 4/genotype) shows that control and P2Y2 cKO mice have similar mean arterial pressures (MAP) during a 12 hr light cycle (T3 = 0.1152, p>0.05) and during a 12 hr dark cycle (T3 = 0.1349, p>0.05). (C) Summary (N = 4/genotype) heart rate (beats/min) during light and dark cycles show similar means for controls and P2Y2 cKO (F1,3=2.896, p>0.05). (D-E), summary (N = 4/genotype) blood pressure (D) and heart rate (E) under room air conditions and during exposure to graded increases in CO2 (values were obtained during the last minute of each condition). Control and P2Y2 cKO animals show similar blood pressure (F1,3=2.051, p>0.05) and heart rate (F2,3=2.896, p>0.05) responses across all experimental conditions. *, indicates significant change from 0% CO2. (F-H) Oxygen consumption (VO2) (F), CO2 production (VCO2) and the respiratory exchange ratio (H) were similar between control (N = 11 animals) and P2Y2 cKO (N = 10 animals) mice. (I-K) Under room air conditions control and P2Y2 cKO mice (N = 7 animals/genotype) showed similar arteriole PO2 (T12 = 0.3080, p>0.05), PCO2 (T12 = 0.7548, p>0.05) and pH (T12 = 0.4437, p>0.05). Blood pressure and heart rate values were compared using a two-way ANOVA with Tukey's post-hoc multiple comparison test. Baseline metabolic activity and blood gas values were compared using an unpaired two-way t-test.