title: Effects of trypsin on cytosolic calcium levels in the rat aortic endothelium.
abstract: The effect of trypsin on vascular tone and the cytosolic calcium concentration ([Ca(2+)](i)) of endothelial and smooth muscle cells were examined in the rat aorta. A calcium indicator, fura-PE3, was used to measure [Ca(2+)](i) simultaneously with vascular tone. In the endothelium-intact rat aorta, carbachol and trypsin increased [Ca(2+)](i) in a dose-dependent manner. In the endothelium-denuded rat aorta, carbachol did not change [Ca(2+)](i), but trypsin slightly increased it. Addition of trypsin to the norepinephrine-stimulated rat aorta relaxed the muscle with an additional increase in [Ca(2+)](i). Under calcium-free conditions, trypsin induced a transient increase in [Ca(2+)](i). Trypsin-induced endothelium-dependent relaxation was inhibited by preincubation with l-NMMA, an endothelial NO synthase inhibitor, U-73122, a phospholipase C inhibitor, cyclopiazonic acid, a sarcoplasmic/endoplasmic reticulum Ca(2+)-ATPase blocker, and lanthanum, a nonselective Ca(2+) channel blocker. However, indomethacin, a nonselective cyclooxygenase inhibitor, and SKF-96365, a store-operated Ca(2+)-channel blocker, had no effect on the trypsin-induced relaxation. These results suggest that trypsin increases [Ca(2+)](i) in the endothelial cells through SKF-96365-insensitive Ca(2+) channels and regulates the release of NO, which results in relaxation of the rat aorta.
authors.affiliation: Department of Veterinary Pharmacology, Yamaguchi University, 1677–1 Yoshida, Yamaguchi 753–8515, Japan.
authors.forename: Daijiro
authors.initials: D
authors.lastname: Kaneko
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Komatsu
authors.forename: Takashi
authors.initials: T
authors.lastname: Ohama
authors.forename: Koichi
authors.initials: K
authors.lastname: Sato
mesh_terms: D000818:Animals; D001011:Aorta / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism; D002217:Carbachol / Q000494:pharmacology; D003600:Cytosol / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000378:metabolism; D007093:Imidazoles / Q000378:metabolism; D008297:Male; D009126:Muscle Relaxation / Q000187:drug effects*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D014357:Trypsin / Q000494:pharmacology*
chemical_list: D015220:Calcium Channels; D007093:Imidazoles; D009569:Nitric Oxide; D002217:Carbachol; D014357:Trypsin; C063159:1-(2-(3-(4-methoxyphenyl)propoxy)-4-methoxyphenylethyl)-1H-imidazole; D002118:Calcium