Role of cystathionine-γ-lyase in hypoxia-induced changes in TASK activity, intracellular [Ca] and ventilation in mice.

Cystathionine-γ-lyase (CSE) is a multifunctional enzyme, and hydrogen sulfide (HS) is one of its products. CSE and HS have recently been proposed to be critical signaling molecules in hypoxia-induced excitation of carotid body (CB) glomus cells and the chemosensory response. Because the role of HS in arterial chemoreception is still debated, we further examined the role of CSE by studying the effects of hypoxia on TASK K channel activity, cell depolarization, [Ca] and ventilation using CSE and CSE mice. As predicted, hypoxia reduced TASK activity and depolarized glomus cells isolated from CSE mice. These effects of hypoxia were not significantly altered in glomus cells from CSE mice. Basal [Ca] and hypoxia-induced elevation of [Ca] were also not significantly different in glomus cells from CSE and CSE mice. In whole-body plethysmography, hypoxia (10%O) increased minute ventilation in both CSE and CSE mice equally well, and no significant differences were found in either males or females when adjusted by body weight. Together, these results show that deletion of the CSE gene has no effects on hypoxia-induced changes in TASK, cell depolarization, [Ca] and ventilation, and therefore do not support the idea that CSE/HS signaling is important for CB chemoreceptor activity in mice.