Please use this identifier to cite or link to this item:
|Title:||Evolved changes in breathing and CO2 sensitivity in deer mice native to high altitudes|
|Authors:||Ivy, Catherine M.|
Scott, Graham R.
|Keywords:||generational effects;hypercapnic ventilatory response;hypoxia acclimation;hypoxic ventilatory response|
|Citation:||Am. J. Physiol. Reg. Integr. Comp. Physiol. 315, R1027–R1037.|
|Abstract:||We examined the control of breathing by O2 and CO2 in deer mice native to high altitude to help uncover the physiological specializations used to cope with hypoxia in high-altitude environments. Highland deer mice (Peromyscus maniculatus) and lowland white-footed mice (P. leuco- pus) were bred in captivity at sea level. The first and second gener- ation progeny of each population was raised to adulthood and then acclimated to normoxia or hypobaric hypoxia (12 kPa O2, simulating hypoxia at ~4,300 m) for 6–8 wk. Ventilatory responses to poikilo- capnic hypoxia (stepwise reductions in inspired O2) and hypercapnia (stepwise increases in inspired CO2) were then compared between groups. Both generations of lowlanders appeared to exhibit ventilatory acclimatization to hypoxia (VAH), in which hypoxia acclimation enhanced the hypoxic ventilatory response and/or made the breathing pattern more effective (higher tidal volumes and lower breathing frequencies at a given total ventilation). In contrast, hypoxia acclima- tion had no effect on breathing in either generation of highlanders, and breathing was generally similar to hypoxia-acclimated lowlanders. Therefore, attenuation of VAH may be an evolved feature of high- landers that persists for multiple generations in captivity. Hypoxia acclimation increased CO2 sensitivity of breathing, but in this case, the effect of hypoxia acclimation was similar in highlanders and lowlanders. Our results suggest that highland deer mice have evolved high rates of alveolar ventilation that are unaltered by exposure to chronic hypoxia, but they have preserved ventilatory sensitivity to CO2 .|
|Appears in Collections:||Biology Publications|
Files in This Item:
|Ivy&Scott_Accepted.pdf||2.34 MB||Adobe PDF||View/Open|
Items in MacSphere are protected by copyright, with all rights reserved, unless otherwise indicated.