Measurement of various respiratory dynamics parameters following acute inhalational exposure to soman vapor in conscious rats

Abstract

Respiratory dynamics were investigated in head-out plethysmography chambers following inhalational exposure to soman in untreated, non-anesthetized rats. A multipass saturator cell was used to generate 520, 560 and 600 mg × min/m3 of soman vapor in a customized inhalational exposure system. Various respiratory dynamic parameters were collected from male Sprague-Dawley rats (300--350 g) during (20 min) and 24 h (10 min) after inhalational exposure. Signs of CWNA-induced cholinergic crisis were observed in all soman-exposed animals. Percentage body weight loss and lung edema were observed in all soman-exposed animals, with significant increases in both at 24 h following exposure to 600 mg × min/m3. Exposure to soman resulted in increases in respiratory frequency (RF) in animals exposed to 560 and 600 mg × min/m3 with significant increases following exposure to 560 mg × min/m3 at 24 h. No significant alterations in inspiratory time (IT) or expiratory time (ET) were observed in soman-exposed animals 24 h post-exposure. Prominent increases in tidal volume (TV) and minute volume (MV) were observed at 24 h post-exposure in animals exposed to 600 mg × min/m3. Peak inspiratory (PIF) and expiratory flow (PEF) followed similar patterns and increased 24 h post-exposure to 600 mg × min/m3 of soman. Results demonstrate that inhalational exposure to 600 mg × min/m3 soman produces notable alterations in various respiratory dynamic parameters at 24 h. The following multitude of physiological changes in respiratory dynamics highlights the need to develop countermeasures that protect against respiratory toxicity and lung injury.