title: Ca(2+)-dependent nitric oxide release in endothelial but not R3230Ac rat mammary adenocarcinoma cells.
abstract: We have characterized the ability of several cell types associated with the microvasculature of solid tumors to release nitric oxide (NO.) in response to increases in cytosolic Ca2+ concentration ([Ca2+]c). EA.hy926 immortalized human umbilical vein endothelial cells (EC), rat fibroblasts (RFL), and tumorigenic cells isolated from R3230Ac rat mammary adenocarcinoma (MaC) were treated with thapsigargin (TG), an inhibitor of Ca(2+)-ATPase. NO. output was measured via a chemiluminescence detection system. Baseline NO. output was detectable only for EC. TG caused a significant increase in EC NO. output that could be blocked with NG-monomethyl-L-arginine and restored with L-arginine. TG did not stimulate NO. release from RFL or MaC cells, despite elevating [Ca2+]c in all cells. A Ca(2+)-dependent isoform of NO synthase (eNOS) was detected by immunoblot only in EC. These data indicate that EC, but not RFL or MaC, are capable of Ca(2+)-dependent NO. release and suggest that any Ca(2+)-dependent NO. release within this tumor is primarily of endothelial (and not tumorigenic cell) origin.
authors: Department of Radiation Oncology, Duke University Medical Center, Durham 27710, USA.
authors: R A
authors: RA
authors: Lindberg
authors: M W
authors: MW
authors: Dewhirst
authors: B J
authors: BJ
authors: Buckley
authors: C S
authors: CS
authors: Hughes
authors: A R
authors: AR
authors: Whorton
mesh_terms: D000230:Adenocarcinoma / Q000378:metabolism* / Q000473:pathology; D000818:Animals; D001120:Arginine / Q000494:pharmacology; D002118:Calcium / Q000502:physiology*; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors; D002460:Cell Line; D004730:Endothelium, Vascular / Q000378:metabolism*; D005260:Female; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D007527:Isoenzymes / Q000378:metabolism; D008325:Mammary Neoplasms, Experimental / Q000378:metabolism* / Q000473:pathology; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000378:metabolism; D051381:Rats; D019284:Thapsigargin / Q000494:pharmacology; D019323:omega-N-Methylarginine / Q000494:pharmacology
chemical_list: D007527:Isoenzymes; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D019284:Thapsigargin; D001120:Arginine; D019001:Nitric Oxide Synthase; D000252:Calcium-Transporting ATPases; D002118:Calcium