Table 2.

Cardio-respiratory parameters in normoxic (21% O₂) and hypoxic (12, 10 and 7% O₂) Columbian ground squirrels during steady state conditions¹

Variable	21% O2	12% O2	10% O2	7% O2
Th (°C)	37.7 ± 0.4	36.8 ± 0.4†	35.4 ± 0.9‡	31.9 ± 0.6‡
Tb (°C)	37.5 ± 0.6	36.7 ± 0.3*	35.1 ± 1.0‡	31.4 ± 0.6‡
(ml O2 kg−1 min−1)	19.1 ± 2.6	17.7 ± 2.0	16.0 ± 1.6	8.80 ± 2.60‡
(ml CO2 kg−1 min−1)	17.2 ± 2.4	17.5 ± 2.8	15.7 ± 1.9	7.91 ± 2.46‡
RER (ml CO2 (ml O2)−1)	0.90 ± 0.04	0.99 ± 0.06	0.99 ± 0.13	0.93 ± 0.15
fH (beats min−1)	248 ± 28	300 ± 12†	295 ± 31†	251 ± 14
VTI (ml kg−1)	9.70 ± 3.53	11.8 ± 4.2	12.5 ± 5.6	8.87 ± 3.0
fR (beats min−1)	72.5 ± 15.1	103 ± 30*	99.3 ± 37.9*	103 ± 7*
(ml kg−1 min−1)	650 ± 168	1130 ± 384†	1080 ± 298†	897 ± 270
(ml O2 ml−1)	34.0 ± 7.4	62.2 ± 16.1†	67.4 ± 17.3‡	103 ± 14‡

Values are mean ±s.d. ¹Steady state refers to measurements obtained after 2 h.

^*Significantly different from normoxic values (P < 0.05).

^†Significantly different from normoxic values (P < 0.01).

^‡Significantly different from normoxic values (P < 0.001).