ASIC1 contributes to pulmonary vascular smooth muscle store-operated Ca(2+) entry.
Acid-sensing ion channels (ASIC) are voltage-insensitive, cationic channels that have recently been identified in vascular smooth muscle (VSM). It is possible that ASIC contribute to vascular reactivity via Na(+) and Ca(2+) conductance; however, their function in VSM is largely unknown. In pulmonary VSM, store-operated Ca(2+) entry (SOCE) plays a significant role in vasoregulatory mechanisms such as hypoxic pulmonary vasoconstriction and receptor-mediated arterial constriction. Therefore, we hypothesized that ASIC contribute to SOCE in pulmonary VSM. We examined SOCE resulting from depletion of intracellular Ca(2+) stores with cyclopiazonic acid in isolated small pulmonary arteries and primary cultured pulmonary arterial smooth muscle cells by measuring 1) changes in VSM [Ca(2+)](i) using fura-2 indicator dye, 2) Mn(2+) quenching of fura-2 fluorescence, and 3) store-operated Ca(2+) and Na(+) currents using conventional whole cell patch-clamp configuration in voltage-clamp mode. The role of ASIC was assessed by the use of the ASIC inhibitors, amiloride, benzamil, and psalmotoxin 1, or siRNA directed towards ASIC1, ASIC2, or ASIC3 isoforms. We found that store-operated VSM [Ca(2+)](i) responses, Mn(2+) influx, and inward cationic currents were attenuated by either pharmacological ASIC inhibition or treatment with ASIC1 siRNA. These data establish a unique role for ASIC1 in mediating SOCE in pulmonary VSM and provide new insight into mechanisms of VSM Ca(2+) entry and pulmonary vasoregulation.
Jernigan
Nikki L
NL
Dept. of Cell Biology and Physiology, Univ. of New Mexico Health Sciences Center, Albuquerque, 87131-0001, USA. NJernigan@salud.unm.edu
Paffett
Michael L
ML
Walker
Benjimen R
BR
Resta
Thomas C
TC
D062565:Acid Sensing Ion Channels; D000584:Amiloride / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D062626:Degenerin Sodium Channels; D062686:Epithelial Sodium Channel Blockers; D053503:Epithelial Sodium Channels / Q000235:genetics / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D005456:Fluorescent Dyes; D016257:Fura-2; D015636:Magnesium Chloride / Q000494:pharmacology; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000502:physiology*; D009419:Nerve Tissue Proteins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism*; D011651:Pulmonary Artery / Q000166:cytology*; D034741:RNA, Small Interfering; D051381:Rats; D017207:Rats, Sprague-Dawley; D012964:Sodium / Q000378:metabolism; D026941:Sodium Channel Blockers / Q000494:pharmacology; D015222:Sodium Channels / Q000235:genetics* / Q000378:metabolism*; D014162:Transfection; D014661:Vasoconstriction / Q000502:physiology
C568269:ASIC3 protein, rat; D062565:Acid Sensing Ion Channels; C568268:Asic1 protein, rat; C568425:Asic2 protein, rat; D062626:Degenerin Sodium Channels; D062686:Epithelial Sodium Channel Blockers; D053503:Epithelial Sodium Channels; D005456:Fluorescent Dyes; D009419:Nerve Tissue Proteins; D034741:RNA, Small Interfering; D026941:Sodium Channel Blockers; D015222:Sodium Channels; D015636:Magnesium Chloride; C013407:benzamil; D000584:Amiloride; D012964:Sodium; D002118:Calcium; D016257:Fura-2