Premium
SK Ca and IK Ca channels are involved in epithelium‐dependent relaxation of rat bronchioles
Author(s) -
Kroigaard Christel,
Dalsgaard Thomas,
Simonsen Ulf
Publication year - 2009
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.23.1_supplement.580.1
Subject(s) - iberiotoxin , apamin , chemistry , bronchiole , charybdotoxin , channel blocker , endocrinology , medicine , biophysics , potassium channel , calcium , biology , lung , organic chemistry
We investigated whether Ca 2+ ‐activated K + channels of small (SK Ca ) and intermediate (IK Ca ) conductance are present, and in bronchioles can be modulated by an opener, NS309 (6,7‐dichloro‐1H‐indole‐2,3‐dione 3‐oxime). Immunohistochemical studies were conducted, and segments of rat bronchioles (847 ± 25 μm, n=51) were mounted in microvascular myographs for isometric tension recordings. The effect of NS309 was compared to that in pulmonary arteries. Immunoreaction for IK Ca and SK Ca 3 was found in rat bronchiole epithelium. In 5‐HT (1 µM)‐contracted rat bronchioles, NS309 (0.01‐10 µM) and a β 2 ‐adrenoceptor agonist, salbutamol, induced concentration‐ and epithelium‐dependent relaxations. An inhibitor of cyclooxygenase, indomethacin (3 µM), a NO‐synthase inhibitor, L‐NNA (100 µM) and a CYP2C9 inhibitor, sulphaphenazole (100 µM), did not reduce NS309 relaxation. In contrast to a blocker of large‐conductance K Ca (BK Ca ) channels, iberiotoxin (0.1 µM), a blocker of IK Ca and BK Ca channels, charybdotoxin (0.07 µM) and a blocker of SK Ca channels, apamin (0.5 μM), reduced salbutamol and NS309‐induced relaxation. The study suggests that IK Ca and SK Ca 3 channels are located in rat bronchiole epithelium, and that activation of SK Ca and IK Ca channels by NS309 leads to epithelium‐derived hyperpolarizing factor (EpDHF)‐type relaxation of bronchioles analogue to the EDHF‐type relaxation in rat pulmonary arteries.