title: Endothelium-dependent frequency modulation of Ca2+ signalling in individual vascular smooth muscle cells of the rat.
abstract: 1. We visualized intracellular Ca2+ concentration ([Ca2+]i) changes, using fluo-3 as an indicator, of individual vascular smooth muscle cells and endothelial cells within intact rat tail arteries by confocal microscopy. 2. Using a piezo-driven objective, we focused on endothelial and smooth muscle cell layers alternately to obtain Ca2+ images of their cells. In the presence of 1 microM acetylcholine (ACh), individual endothelial cells responded with intermittent increases in the [Ca2+]i (Ca2+ oscillations). At the same time, the frequency of Ca2+ oscillations in smooth muscle cells induced by electrical stimulation of the perivascular sympathetic nerve was greatly decreased. 3. A [Ca2+]i rise during the oscillations in the endothelial cells propagated in the form of a wave along the long axis of the cells. 4. In the presence of a NO synthase inhibitor, no significant inhibitory effect of ACh on the Ca2+ signalling in the vascular smooth muscle cells was detected, although the Ca2+ oscillations in the endothelial cells persisted. 5. The inhibitory effect of ACh on the frequency of Ca2+ oscillations in the vascular smooth muscle cells was mimicked by 1 microM sodium nitroprusside, a NO donor. 6. These results indicate that Ca2+ waves and oscillations in vascular endothelial cells regulate NO production, which modulates vascular tone by decreasing the frequency of Ca2+ oscillations in smooth muscle cells activated by sympathetic agonists.
authors.affiliation: Department of Pharmacology, Faculty of Medicine, University of Tokyo, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Kasai
authors.forename: T
authors.initials: T
authors.lastname: Yamazawa
authors.forename: T
authors.initials: T
authors.lastname: Sakurai
authors.forename: Y
authors.initials: Y
authors.lastname: Taketani
authors.forename: M
authors.initials: M
authors.lastname: Iino
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000814:Aniline Compounds / Q000378:metabolism; D000818:Animals; D001158:Arteries; D001685:Biological Factors / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D004558:Electric Stimulation; D004730:Endothelium, Vascular / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005456:Fluorescent Dyes / Q000378:metabolism; D007091:Image Processing, Computer-Assisted; D008297:Male; D008856:Microscopy, Fluorescence; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D009599:Nitroprusside / Q000494:pharmacology; D011726:Pyridinium Compounds / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction; D012964:Sodium / Q000494:pharmacology; D014966:Xanthenes / Q000378:metabolism
chemical_list: D000814:Aniline Compounds; D001685:Biological Factors; D004791:Enzyme Inhibitors; D005456:Fluorescent Dyes; D011726:Pyridinium Compounds; D014966:Xanthenes; C067410:endothelium-dependent hyperpolarization factor; C052247:4-(4-diethylaminostyryl)-N-methylpyridinium; D009599:Nitroprusside; C059715:Fluo-3; D009569:Nitric Oxide; D012964:Sodium; D019001:Nitric Oxide Synthase; D000109:Acetylcholine; D002118:Calcium