Table 1.
Weight and temperature of 6-day-old Phox2b+/− and Phox2b+/+ mice.
| 33°C | 26°C | G × T | |||||
|---|---|---|---|---|---|---|---|
| Phox2b+/+ | Phox2b+/− | p | Phox2b+/+ | Phox2b+/− | p | p | |
| HYPOXIA STUDY | |||||||
| n | 41 | 43 | 84 | 85 | |||
| Weight (g) | 3.4 (0.5) | 2.8 (0.4) | <0.0001 | 3.7 (0.6)* | 3.0 (0.5)* | <0.0001 | NS |
| T° initial (°C) | 33.9 (1.1) | 33.7 (1.0) | NS | 33.5 (1.5) | 33.3 (1.4) | NS | NS |
| T° final (°C) | 34.8 (0.6) | 34.6 (0.7) | NS | 30.5 (1.1)**** | 29.8 (1.4)**** | <0.0003 | <0.0608 |
| T° chamber (°C) | 33.0 (0.3) | 33.0 (0.3) | NS | 26.0 (0.3) | 26.0 (0.2) | NS | NS |
| T° infrared (°C) | – | – | 31.8 (0.6) | 30.8 (1.1) | 0.0001 | – | |
| HYPERCAPNIA STUDY | |||||||
| n | 34 | 36 | 51 | 45 | |||
| Weight (g) | 3.7 (0.5) | 3.4 (0.7) | <0.0439 | 3.7 (0.5) | 3.3 (0.7) | 0.0006 | NS |
| T° initial (°C) | 34.3 (1.1) | 34.4 (1.2) | NS | 34.1 (1.4) | 33.7 (1.4)* | NS | NS |
| T° final (°C) | 34.8 (1.2) | 34.9 (0.8) | NS | 30.8 (1.0)**** | 30.4 (0.8)**** | 0.0321 | NS |
| T° chamber (°C) | 33.0 (0.4) | 32.9 (0.4) | NS | 26.2 (0.4) | 26.2 (0.4) | NS | |
Weight and interscapular skin temperature were measured immediately after taking the pup from the litter (T° initial). The p-value refers to the comparison between Phox2b+/+ and Phox2b+/− groups. Comparison of 33 versus 26°C for each genotype group; *p < 0.05; ****p < 0.0001. Values indicate mean (SD) for each group. G × T: p-value for Genotype by Temperature interaction. Note that G × T interactions were marginally significant in the hypoxic study and therefore that genotype-related differences in final temperatures are unwarranted. Infrared temperature were not measured at 33°C, due to the lack of infrared image of the pup in thermoneutral conditions.