Developmental nicotine exposure eliminates the ventilatory response to a brief episode of severe hypoxia, independently of sex.

Abstract

We tested the hypothesis that developmental nicotine exposure (DNE) disrupts the cardiorespiratory response to brief, severe hypoxia by measuring ventilatory and heart rate during a 15 s epoch of Nbreathing in one-to-six-day-old Sprague Dawley rat pups. Data were analyzed with a 3-way ANOVA, with inspired Oconcentration, treatment group and sex the main factors. As expected, Nbreathing significantly increased the inspired pulmonary ventilation rate (V˙) in control pups of both sexes, driven by an increase of tidal volume. In contrast, neither male nor female DNE pups increased V̇ during the Nchallenge. There was no effect of hypoxia on heart rate in any group. These findings reveal a selective vulnerability: DNE specifically compromises the respiratory system's ability to increase ventilation in response to brief severe hypoxia. This dissociation between ventilatory and heart rate responses to severe hypoxia provides fresh insight into the impact of DNE on cardiorespiratory function during a critical developmental stage.