Fig. 8. Effects of hydrogen sulfide (H2S) inhalation on carbon dioxide (CO2) production ( closed inverted triangles ) and heart rate ( open squares ) in mice breathing H2S (80 ppm) for 30 min at ambient temperature (Ta) 27°C, followed by a 30-min recovery period breathing air at Ta27°C. n = 3, * P < 0.05 versus time 0.