Impaired NO-dependent inhibition of store- and receptor-operated calcium entry in pulmonary vascular smooth muscle after chronic hypoxia.
We have recently demonstrated that chronic hypoxia (CH) attenuates nitric oxide (NO)-mediated decreases in pulmonary vascular smooth muscle (VSM) intracellular free calcium concentration ([Ca2+]i) and promotes NO-dependent VSM Ca2+ desensitization. The objective of the current study was to identify potential mechanisms by which CH interferes with regulation of [Ca2+]i by NO. We hypothesized that CH impairs NO-mediated inhibition of store-operated (capacitative) Ca2+ entry (SOCE) or receptor-operated Ca2+ entry (ROCE) in pulmonary VSM. To test this hypothesis, we examined effects of the NO donor, spermine NONOate, on SOCE resulting from depletion of intracellular Ca2+ stores with cyclopiazonic acid, and on UTP-induced ROCE in isolated, endothelium-denuded, pressurized pulmonary arteries (213 +/- 8 microm inner diameter) from control and CH (4 wk at 0.5 atm) rats. Arteries were loaded with fura-2 AM to continuously monitor VSM [Ca2+]i. We found that the change in [Ca2+]i associated with SOCE and ROCE was significantly reduced in vessels from CH animals. Furthermore, spermine NONOate diminished SOCE and ROCE in vessels from control, but not CH animals. We conclude that NO-mediated inhibition of SOCE and ROCE is impaired after CH-induced pulmonary hypertension.
Jernigan
Nikki L
NL
Vascular Physiology Group, Dept. of Cell Biology and Physiology, Univ. of New Mexico Health Sciences Center, MSC 08-4750, 1 Univ. of New Mexico, Albuquerque, NM 87131-0001, USA.
Broughton
Brad R S
BR
Walker
Benjimen R
BR
Resta
Thomas C
TC
D000818:Animals; D001993:Bronchodilator Agents / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors; D002908:Chronic Disease; D004730:Endothelium, Vascular / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006976:Hypertension, Pulmonary / Q000378:metabolism / Q000473:pathology; D000860:Hypoxia / Q000378:metabolism*; D007211:Indoles / Q000494:pharmacology; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009569:Nitric Oxide / Q000494:pharmacology*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D009589:Nitrogen Oxides / Q000494:pharmacology; D011651:Pulmonary Artery / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013096:Spermine / Q000031:analogs & derivatives / Q000494:pharmacology; D014544:Uridine Triphosphate / Q000494:pharmacology
D001993:Bronchodilator Agents; D015220:Calcium Channels; D004791:Enzyme Inhibitors; D007211:Indoles; D020030:Nitric Oxide Donors; D009589:Nitrogen Oxides; C091861:spermine nitric oxide complex; D013096:Spermine; D009569:Nitric Oxide; D000252:Calcium-Transporting ATPases; D002118:Calcium; D014544:Uridine Triphosphate; C000543:cyclopiazonic acid