Hydrogen sulfide ameliorates prenatal cigarette smoke exposure-induced impairment of respiratory responses to hypercapnia in neonatal rats

The present study was designed to investigate whether H2S could improve the respiratory responses to hypercapnia blunted by prenatal CSE in neonatal rats in vivo. Respiratory activities were recorded with head-out body plethysmography. The results showed that during baseline, respiratory frequency (FR), tidal volume (VT) and minute ventilation (VE) were similar among tested groups; frequency of spontaneous apnea (FSA), not post-sigh apnea (FPA), was significantly elevated by prenatal CSE. During hypercapnia, the increases in FR and VE were significantly reduced, but VT was not markedly different, in CSE group; both FSA and FPA were decreased, although FSA remained higher in CSE group. All the aforementioned effects induced by CSE on respiratory activities were relieved by NaHS (donor of H2S, 56 μmol/kg by intraperitoneal injection). These data indicate that H2S could ameliorate the disruption of respiratory responses to hypercapnia induced by prenatal CSE in neonatal rats.