I think that the reason for the differences in CO2 sensitivity will be due to the differences in baseline breathing rate at rest and whether they are at the extremes of what is considered average in humans and in other animals.

to be continued……..

Individual differences in rat sensitivity to CO₂

• Lucía Améndola, Anna Ratuski, Daniel M. Weary 

Abstract

Feelings of fear, anxiety, dyspnea and panic when inhaling carbon dioxide (CO₂) are variable among humans, in part due to differences in CO₂ sensitivity. Rat aversion to CO₂ consistently varies between individuals; this variation in aversion may reflect CO₂ sensitivity, but other personality traits could also account for individual differences in aversion. The aims of this study were to 1) assess the stability of individual differences in rat aversion to CO₂, 2) determine if individual differences in sweet reward motivation are associated with variation in aversion to CO₂, and 3) assess whether variation in aversion to CO₂ is related to individual differences in motivation to approach gains (promotion focus) or maintain safety (prevention focus). Twelve female Sprague Dawley rats were exposed multiple times at three different ages (3, 9 and 16 months old) to CO₂ in approach-avoidance testing to assess motivation to avoid CO₂ against motivation to gain sweet rewards. Rats were also tested for motivation to find hidden sweet rewards, and for their motivation to approach rewards or darkness. Tolerance to CO₂ increased with repeated exposures and was higher at older ages. Individual differences in aversion to CO₂were highly repeatable but unrelated to motivation for sweet rewards or the strength of promotion and prevention focus. These results indicate that individual differences in aversion to CO₂ reflect variation in CO₂ sensitivity.

• Published: January 22, 2021
• https://doi.org/10.1371/journal.pone.0245347