Cardiorespiratory responses to hypercapnia in chickens after embryonic exposure to CO 2

We evaluated cardiorespiratory responses to 7% CO 2 of 10 (d10) and 21 (d21) days old broiler males (M) and females (F) after embryonic hypercapnia (1.5% CO 2 ) and control situation (CS). Under normocapnia no difference in ventilation (V E ), tidal volume, respiratory frequency, mean arterial pressure (MAP) and heart rate (HR) was observed between groups. Hypercapnia promoted a higher V E in Fd10 and Fd21 incubated in 1.5%CO 2 compared with FCS (Fd10 control: 1497±213.4 vs Fd10 1.5% CO 2 : 1834±111.6; Fd21 control: 179±36.24 vs Fd21 1.5% CO 2 : 389±86.4 mLkg −1 min − 1 ). Only Md21 incubated with 1.5% CO 2 presented higher V E compared with CS (Md10 control: 1728±289.6 vs Md10 1.5% CO 2 : 1823±209; Md21 control: 239±40.4 vs Md21 1.5% CO 2 : 388±77.5 mLkg −1 min −1 ). MAP was not different between groups, however, HR was higher in Fd10 incubated in 1.5% CO 2 compared to Fd10 incubated in CS during hypercapnic exposure (Fd10 control: 351±25.1 vs Fd10 1.5% CO 2 : 405±14.8; Fd21 control: 324±11.8 vs Fd21 1.5% CO 2 : 331± 19.6 beats.min −1 ). Therefore, cardiorespiratory responses to hypercapnia are higher in animals incubated with 1.5% CO 2 compared to control animals and these responses are more pronounced in females. Financial Support: FAPESP, CNPq and INCT of Comparative Physiology.