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Gene expression of TREK K+ channels in rat carotid body (CB)
Author(s) -
Kim Insook,
Yang DJ,
Carroll John L.
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.5.a1230
Subject(s) - gene expression , downregulation and upregulation , glomus cell , carotid body , gene , real time polymerase chain reaction , biology , microbiology and biotechnology , endocrinology , andrology , medicine , genetics , stimulation
Oxygen sensing by CB glomus cells shows postnatal development in mammals. Both hypoxia‐induced depolarization and [Ca 2+ ] i response are small at birth and increase with age, but mechanisms are poorly understood. We hypothesized that expression of TREK‐1, a two‐pore domain K + channel, may regulate glomus cell excitability during development. Therefore, we tested whether a) TREK‐1 is expressed in rat CB; b) TREK‐1 expression changes with age; and c) chronic hypoxia (CH) from birth alters TREK‐1 expression. rTREK‐1 and rTREK‐2 primers were tested on rat CB of normoxic 0–1day old (N1), 14–16 days old (N14), and 2 weeks of CH after birth with quantitative real time RT‐PCR (qRT‐PCR) by using SYBR green. 18s rRNA gene was used as the reference gene and relative gene expression ratio was calculated (Pfaffl MW 2001). Results Immunoreactivity for hTREK‐1 was found only in glomus cells at both ages. Between P0 and P14, rTREK‐1 expression declined, while rTREK‐2 expression did not. TREK‐1 and TREK‐2 relative gene expression ratio for N1 vs. N14 CB were 0.16 ± 0.03 (n=6) (p<0.001, downregulation) and 0.93 ± 0.22 (n=4) (NS), respectively. In sharp contrast, in rats reared in 0.12 FiO 2 from P0 to P14, TREK‐1 expression showed almost 2 fold upregulation. The sequence of qRT‐PCR amplicon of rat CB TREK‐1 showed 100% homology with that of rat cerebellum TREK‐1. We conclude that a) TREK‐1 and TREK‐2 are expressed in CB glomus cells; b) TREK‐1 expression decreases >80% between P0 and P14; and c) expression of TREK‐1 after birth appears to be regulated by oxygen tension. Developmental changes in TREK‐1 potassium channel expression may play a role in CB functional maturation. (funded by NIH R01 HL54621 and UAMS Dean's Research Development Fund).