RT Journal Article
SR Electronic
T1 Properties of a store-operated nonselective cation channel in airway smooth muscle
JF European Respiratory Journal
JO Eur Respir J
FD European Respiratory Society
SP 1529
OP 1538
DO 10.1183/09031936.00054608
VO 32
IS 6
A1 P. B. Helli
A1 L. J. Janssen
YR 2008
UL http://erj.ersjournals.com/content/32/6/1529.abstract
AB Passive depletion of internal Ca2+ stores in airway smooth muscle (ASM) activates nonselective cation channels (NSCCs) that mediate capacitative Ca2+ entry. However, the single channel properties of these cation channels have yet to be resolved and their regulation by cytosolic Ca2+ levels ([Ca2+]i) still remains unclear. NSCC currents and changes in [Ca2+]i during passive depletion of internal Ca2+ stores were monitored in isolated bovine tracheal myocytes. Loading cells with 1,2-bis(o-aminophenoxy)ethane-N,N,N′,N′-tetracetic acid acetyl methyl ester (BAPTA-AM) to reduce [Ca2+]i and thereby deplete the store augmented a basal Gd3+- and La3+-sensitive, Ca2+-permeable NSCC current. This current mimics that which is evoked by store depletion using the sarcoplasmic reticulum Ca2+ pump inhibitor cyclopiazonic acid (which concurrently and transiently elevates [Ca2+]i). Both interventions activated an ∼25-pS NSCC with properties identical to both spontaneous (basal) and BAPTA-AM-evoked single channel currents. In summary, the present study provides novel evidence that a lanthanide-sensitive, 25-pS nonselective cation channel underlies both basal and store depletion-evoked membrane currents in airway smooth muscle and that this conductance likely contributes to the regulation of resting [Ca2+]i and capacitative Ca2+ entry.