NO upregulation of a cyclic nucleotide-gated channel contributes to calcium elevation in endothelial cells.
We investigated whether nitric oxide (NO) upregulates a cyclic nucleotide-gated (CNG) channel and whether this contributes to sustained elevation of intracellular calcium levels ([Ca(2+)](i)) in porcine pulmonary artery endothelial cells (PAEC). Exposure of PAEC to an NO donor, NOC-18 (1 mM), for 18 h increased the protein and mRNA levels of CNGA2 40 and 50%, respectively (P < 0.05). [Ca(2+)](i) in NO-treated cells was increased 50%, and this increase was maintained for up to 12 h after removal of NOC-18 from medium. Extracellular calcium is required for the increase in [Ca(2+)](i) in NO-treated cells. Thapsigargin induced a rapid cytosolic calcium rise, whereas both a CNG and a nonselective cation channel blocker caused a faster decline in [Ca(2+)](i), suggesting that capacitive calcium entry contributes to the elevated calcium levels. Antisense inhibition of CNGA2 expression attenuated the NO-induced increases in CNGA2 expression and [Ca(2+)](i) and in capacitive calcium entry. Our results demonstrate that exogenous NO upregulates CNGA2 expression and that this is associated with elevated [Ca(2+)](i) and capacitive calcium entry in porcine PAEC.
Zhang
Jianliang
J
Department of Medicine, University of Florida, Gainesville, FL 32608-1197, USA. zhangjl@medicine.ufl.edu
Xia
Shen-Ling
SL
Block
Edward R
ER
Patel
Jawaharlal M
JM
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D054815:Cyclic Nucleotide-Gated Cation Channels; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D015870:Gene Expression / Q000187:drug effects; D049452:Green Fluorescent Proteins; D015151:Immunoblotting; D007424:Intracellular Fluid / Q000378:metabolism; D007473:Ion Channels / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D008164:Luminescent Proteins / Q000096:biosynthesis / Q000235:genetics; D009569:Nitric Oxide / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D011651:Pulmonary Artery; D012333:RNA, Messenger / Q000037:antagonists & inhibitors; D013552:Swine; D014162:Transfection; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology*
D054815:Cyclic Nucleotide-Gated Cation Channels; D007473:Ion Channels; D008164:Luminescent Proteins; D020030:Nitric Oxide Donors; D016376:Oligonucleotides, Antisense; D012333:RNA, Messenger; D049452:Green Fluorescent Proteins; D009569:Nitric Oxide; D002118:Calcium