Objective To study the releases of endothelin-1 and prostacyclin by endothelial cells in culture and to elucidate how these releases were influenced by smoke-treated low density lipoprotein. Methods We exposed endothelial cell cultures to native or oxidized Iow density lipoproteins,low density lipoproteins treated by dimethylsulfoxide-soluble particles from cigarette smoke or dimethylsulfoxide alones. The release of endothelin-1 was assayed by bioassay and the release of prostacyclin was assayed by radioimmunoassay. Results Low density lipoproteins treated by smoke significantly increased the release of endothelin-l (P＜0. 025) and decreased the release of prostacyclin (P＜0. 02) by endothelial cells in culture, contrast to native or dimethylsulfoxide-treated lipoproteins. Conclusion The main part of vasoconstrictor activity in conditioned medium from bovine aortic EC is endothelin-1.

AIMTo determine the involvement of extracellular signal-regulated kinase 1/2 (ERK1/2) pathway in the expression of endothelin receptor type B (ETB) during culture.

METHODSSB386023, a specific inhibitor for ERK1/2 pathway, was used to define the intracellular signaling pathway for the upregulation of ETB receptors and sarafotoxin 6c (S6c), a selective agonist for ETB receptors, induced contraction in isolated rat superior mesenteric arteries. The contraction was recorded by a sensitive in vitro myograph and the receptor mRNA was quantified by a real-time PCR. The phosphorylated ERK1/2 proteins were analyzed by phosphoELISA assay.

RESULTSS6c induced strong contractile responses of the artery after culture for 24 h, while there was no response to S6c in fresh vessel segments. The enhanced contractile response to S6c paralleled with an increase of mRNA for ETB receptors. The phosphorylated ERK1/2 proteins significantly increased after culture for 3 h. After co-culture with SB386023 for 24 h, S6c-induced contractions significantly decreased with reduction of Emax from (217 +/- 14) % to (127 +/- 23) % (P <0.01). This response paralleled with a decreased level of ETB receptor mRNA.

CONCLUSIONERK1/2 pathway was involved in the up-regulation of ETB receptors on smooth muscle cells isolated from rat mesenteric arteries during culture.

Animals ; Cells, Cultured ; Male ; Mesenteric Arteries ; cytology ; Mitogen-Activated Protein Kinase 1 ; antagonists & inhibitors ; metabolism ; Mitogen-Activated Protein Kinase 3 ; antagonists & inhibitors ; metabolism ; Muscle Contraction ; drug effects ; Muscle, Smooth, Vascular ; cytology ; metabolism ; Organ Culture Techniques ; Phosphorylation ; RNA, Messenger ; biosynthesis ; genetics ; Rats ; Rats, Sprague-Dawley ; Receptor, Endothelin B ; biosynthesis ; genetics ; Signal Transduction ; Up-Regulation ; Vasoconstrictor Agents ; pharmacology ; Viper Venoms ; pharmacology

AIMTo study the vasodilation effect of atropine and its mechanism.

METHODSIsometric tension was recorded in isolated rat super mesenteric arteries precontracted by noradrenaline (NE) to study the vasodilation effect of atropine, and to investigate the role of endothelial cell and vascular smooth muscle cell on vasodilation.

RESULTSAtropine was shown to significantly dilate the endothelium-intact and endothelium-denuded arteries precontracted by NE. Nomega-Nitro-L-arginine methyl ester (L-NAME, nitric oxide synthase inhabitor), indomethacin (cyclooxygenase inhibitor), propranolol (general beta adrenoceptor antagonist) and glibenclamide (ATP sensitive potassium channel inhibitor) showed no effect on vasodilation of atropine. Atropine did not affect the concentration-contraction curve of K+. However, atropine suppressed the contraction induced by NE and CaCl2, but not that by caffeine in the Ca+ -free Krebs solution.

CONCLUSIONAtropine showed significant vasodilation effect which may derive, in part, from endothelium. Besides, atropine could inhibit the receptor-mediated Ca2+ -influx and Ca2+ -release, which was inferred to the mechanism of atropine on vasodilation.

Animals ; Atropine ; pharmacology ; Calcium ; metabolism ; Calcium Chloride ; antagonists & inhibitors ; Cyclooxygenase Inhibitors ; pharmacology ; Endothelial Cells ; physiology ; Female ; In Vitro Techniques ; Indomethacin ; antagonists & inhibitors ; Male ; Mesenteric Artery, Superior ; drug effects ; NG-Nitroarginine Methyl Ester ; antagonists & inhibitors ; Nitric Oxide Synthase ; antagonists & inhibitors ; Norepinephrine ; antagonists & inhibitors ; Potassium Chloride ; antagonists & inhibitors ; Rats ; Rats, Sprague-Dawley ; Vasodilation ; drug effects ; Vasodilator Agents ; pharmacology