Role of Kir2.2 in hypercapnic ventilatory response during postnatal development of mouse

In order to determine the role of Kir2.2 in the hypercapnic ventilatory response (HCVR) during postnatal development, we measured the response of the Kir2.2-knockout (Kir2.2−/−) mouse in an unanesthetized unrestrained state by means of pressure plethysmography on postnatal days 9-10, 14-15 and 18, and compared the response with that in its wild counterpart, the FVB mouse. We also examined developmental changes in m-RNA expression of Kir2.2 in the brainstem of the FVB mouse using quantitative real-time PCR assay. Kir2.2−/− exhibited a smaller increase in tidal volume and minute ventilation volume than the FVB mouse in response to hypercapnic challenge on days 14-15. Meanwhile, the FVB mouse showed a transient increase in m-RNA expression of Kir2.2 in the brainstem on days 14-15. These findings suggest that Kir2.2 in the brainstem plays a transient role in HCVR, possibly through central ventilatory chemosensitivity, during postnatal development.