Does Behavioral Inhibition Affect the Breathing Response to Elevated CO2? Implications for a Respiratory Stress Response.

Abstract

Behavioral inhibition (BI) is a temperament characteristic in which an individual tends to avoid unfamiliar situations or environments. Individuals with high BI are more vulnerable to developing an anxiety disorder, such as Post‐Traumatic Stress Disorder (PTSD), when placed under stressful conditions (Gladstone and Parker, 2005). Behaviorally inhibited organisms learn faster and are slower to extinguish the response to a stimulus (Sheynin et al., 2013; Servatius et al.,, 2008). Our lab over the past several years has been investigating the relationship between a respiratory stress response to CO2 and BI. In this study, participants played a computer game used previously by Sheynin et al., 2013, to evaluate avoidance acquisition and extinction. BI and non‐BI individuals were separated based on Adult Measure of Behavioral Inhibition (AMBI) and Retrospective Measure of Behavioral Inhibition (RMBI). Gas volumes of 4.5% and 7.0% CO2 were applied as different doses of a respiratory stimulant to further the understanding of any physiological differences in breathing between those with BI compared to those without. We hypothesize that individuals with high BI exhibit differences in all parameters of breathing compared to non‐BI individuals during both levels of CO2, and therefore predict that individuals with high BI respond more robustly to CO2. The 4.5% and 7.0% CO2 were obtained by mixing room air with pure CO2 in a Tissot Spirometer and validated using an Oxygraph O2 and CO2 analyzer. The mixed gas was then delivered from a 100 liter gas bag attached to a breathing tube attached to a Hans Rudolph two‐way non‐rebreathing valve. The subjects placed a two‐way valve attached to a mouthpiece into their mouths and then had a nose clip placed over their noses to create a tight seal between the breathing gas bags and themselves. Respiratory data were collected using a BioPac computer data collection system. Our sample sizes are for 4.5% CO2 – Air BI (n=8) and for non‐BI (n=7), and for 7.0% CO2 – Air BI (n=5) and for non‐BI (n=7). When the data were analyzed there were no apparent differences for VT, VI, Fbr between BI and non‐BI individuals exposed to 7.0% CO2, however, in the 4.5% CO2 breathing parameters there was a marked increased both in absolute value and in percent change for Fbr for BI individuals when compared to non‐BI individuals. Given the small sample sizes of the groups, we conclude that increasing the sample sizes is necessary before any more substantive conclusions can be drawn. In addition, our future studies will include measurements of heart rate, blood pressure, salivary cortisol and salivary amylase.Support or Funding InformationNASA Training Grant #NNX15Aj12H, Wisconsin Space Grant Consortium Infrastructure Grant, RIP‐17 #30116‐03This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.