Ventilation and oxygen consumption in the guinea pig

Respiratory values were determined in guinea pigs studied under normal laboratory conditions in Denver. The effects of anesthesia and acute hypercapnia were also assessed. In normal laboratory conditions, VO2 and VE were proportional to body weight (BW). Specific VO2 and VE for small guinea pigs (mean BW: 269 g) were 1.14 +/- 0.04 (SEM) and 57.5 +/- 3.9 ml/g X h, respectively, compared to 0.82 +/- 0.03 (P less than 0.001) and 29.9 +/- 0.8 ml/g X h (P less than 0.001), respectively, for large animals (mean BW: 817 g). Tidal volume (VT) was related to BW by the following equation: VT (ml) = 3.97 X 10(-3) BW (g) + 2.05 (r = 0.82; P less than 0.001). During anesthesia VO2 decreased 25-63% and VE was reduced by 45% in those animals having the largest change in VO2. In hypercapnia, VE was more than twice that in normocapnia primarily due to a 75-95% elevation in VT.