title: Autocrine action and its underlying mechanism of nitric oxide on intracellular Ca2+ homeostasis in vascular endothelial cells.
abstract: The rise in cytosolic Ca(2+) concentration (Ca(2+)(i)) in vascular endothelial cells (ECs) activates the production and release of nitric oxide (NO). NO modifies Ca(2+)(i) homeostasis in many types of nonendothelial cells. However, its effect on endothelial Ca(2+)(i) homeostasis at basal and excited states remains unclear. In the present study, to elucidate the effect of NO on basal Ca(2+)(i), inositol 1,4,5-trisphosphate-induced Ca(2+)(i) release (IICR) was blocked by expressing an antisense against type-1 inositol 1,4,5-trisphosphate receptors or by microinjecting heparin to individual ECs, and the effects of NO that was released by and diffused from adjacent IICR-intact ECs were recorded. After ATP or bradykinin stimulation, IICR-inhibited ECs showed a marked reduction of basal Ca(2+)(i), which was abolished by N(G)-monomethyl-l-arginine monoacetate pretreatment. The reduction disappeared in sparsely seeded ECs. Exogenous NO gas mimicked the effect of ATP or bradykinin to reduce basal Ca(2+)(i). Blocking plasma membrane Ca(2+)-ATPase (PMCA), but not Na(+)-Ca(2+) exchange or sarcoplasmic/endoplasmic reticulum Ca(2+)-ATPase, suppressed the reduction, indicating that the reduction resulted from a NO-dependent potentiation of PMCA. To elucidate the effect of NO on elevated Ca(2+)(i), ATP-, bradykinin-, or thapsigargin-evoked Ca(2+)(i) response in the presence and absence of NO production was compared in adjacent IICR-intact ECs. NO was found to potentiate PMCA, which, in turn, greatly attenuated agonist-evoked Ca(2+)(i) elevation. NO also potentiated Ca(2+) influx, which markedly increased the sustained phase of Ca(2+)(i) elevation and possibly NO production. NO did not affect other Ca(2+)(i)-elevating and Ca(2+)(i)-sequestrating components. Thus, NO-dependent potentiation of PMCA is crucial for Ca(2+)(i) homeostasis over a wide Ca(2+)(i) range.
authors.affiliation: Second Department of Internal Medicine, the Department of Oral and Maxillofacial Surgery, and the Human Genome Center, Institute of Medical Science, University of Tokyo, Tokyo 113-0033, Japan.
authors.forename: J
authors.initials: J
authors.lastname: Chen
authors.forename: Y
authors.initials: Y
authors.lastname: Wang
authors.forename: T
authors.initials: T
authors.lastname: Nakajima
authors.forename: K
authors.initials: K
authors.lastname: Iwasawa
authors.forename: H
authors.initials: H
authors.lastname: Hikiji
authors.forename: M
authors.initials: M
authors.lastname: Sunamoto
authors.forename: D K
authors.initials: DK
authors.lastname: Choi
authors.forename: Y
authors.initials: Y
authors.lastname: Yoshida
authors.forename: Y
authors.initials: Y
authors.lastname: Sakaki
authors.forename: T
authors.initials: T
authors.lastname: Toyo-Oka
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D001920:Bradykinin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000502:physiology; D002417:Cattle; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D006493:Heparin / Q000494:pharmacology; D006706:Homeostasis; D015544:Inositol 1,4,5-Trisphosphate / Q000502:physiology; D008969:Molecular Sequence Data; D009569:Nitric Oxide / Q000502:physiology*; D014162:Transfection; D019323:omega-N-Methylarginine / Q000494:pharmacology
chemical_list: D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D015544:Inositol 1,4,5-Trisphosphate; D000255:Adenosine Triphosphate; D006493:Heparin; D000252:Calcium-Transporting ATPases; D001920:Bradykinin; D002118:Calcium