TASK and TREK channels in rat carotid body chemoreceptor cells during postnatal development

Abstract

Oxygen sensitivity in carotid body (CB) glomus cells are small at birth and fully developed in two weeks, but mechanism for this phenomenon is poorly understood. Two background K+ channels that regulate excitability of CB cells include TASK and TREK channels. Therefore, we hypothesized that changes in oxygen sensitivity during development may be due to modulated gene expression of TASK and TREK channels. To test this idea, expression of TASKs and TREKs mRNA and membrane K+ currents were determined in P0‐1d (postnatal 0‐1 day) and P14‐18d (postnatal 14‐18 days) CB cells. qRT‐PCR was performed using two stable reference genes, PPIA and TBP, and TASK and TREK currents were recorded in cell‐attached patches. TASK‐1 and TASK‐3 channel mRNA showed no significant difference between two age groups (p>0.05). In agreement with this finding, TASK channels of similar open probabilities were recorded from ~90% of patches from both age groups. Unlike TASKs, TREK‐1 and TREK‐2 mRNA in P0‐1d CB were significantly higher than those in P14‐18d CB. Consistent with these results, TREK‐like channels were recorded in ~35% of patches in P0‐1d CB, but none in P14‐18d CB. These results suggest that expression of TREKs undergoes down‐regulation during development, whereas expression of TASKs does not. The changes in TREK channel expression may therefore affect oxygen sensing during development. (Funded by NIH R01 HL54621 and UAMS CUMG).