Differential expression of large-conductance Ca2+-activated K channels in the carotid body between DBA/2J and A/J strains of mice

作者：Otsubo Toshiki; Kostuk Eric W; Balbir Alexander; Fujii Koichi; Shirahata Machiko^*

来源：Frontiers in Cellular Neuroscience, 2011, 5: 1-8.

DOI：10.3389/fncel.2011.00019

• chemoreceptor
• glomus cell
• hypoxia
• patch clamp
• oxygen
• RT-PCR

The carotid body (CB) is a primary chemosensory organ for arterial hypoxia. Inhibition of K channels in chemosensory glomus cells (GCs) are considered to be responsible for hypoxic chemoreception and/or chemotransduction of the CB. Hypoxic sensitivity of large-conductance calcium-activated K (BK) channels has been established in the rat CB. Our previous work has shown the BK channel beta 2 subunits are more expressed in the CB of the DBA/2J mouse than that of the A/J mouse. Because the DBA/2J mouse is more sensitive to hypoxia than A/J mouse, our general hypothesis is that BK channels play a role in the sensitivity of the mouse CB to mild hypoxia. We performed vigorous analysis of the gene expression of alpha, beta 2, and beta 4 subunits of BK channels in the CB. We found that alpha and beta 2 subunits were expressed more in the CB of the DBA/2J mice than that of the A/J mice. No differences were found in the beta 4 subunit expression. These differences were not seen in the neighboring tissues, the superior cervical ganglion and the carotid artery, suggesting that the differences are CB specific. Further, the sensitivity of BK channels in GCs to mild hypoxia was examined in patch clamp experiments using undissociated CBs. Iberiotoxin significantly inhibited K current of GCs in the DBA/2J mice, but not in the A/J mice. When reducing PO2 to similar to 70 mmHg, K current reversibly decreased in GCs of the DBA/2J, but not of the A/J mice. In the presence of iberiotoxin, mild hypoxia did not inhibit K current in either strains. Thus, the data suggest that BK channels in GCs of the DBA/2J mice are sensitive to mild hypoxia. Differential expression of BK channel beta subunits in the CBs may, at least in part, explain the different hypoxic sensitivity in these mouse strains.

• 出版日期2011-10-11