Mechanisms of endothelin-induced macromolecular leakage in microvascular beds of rat mesentery.
Microvascular responses to endothelin-3 were investigated in the rat mesentery under fluorescence microscopy. Endothelin-3 in a range of 0.1-100 pM induced arteriolar constriction in a dose-dependent manner, and stimulated Ca2+ mobilization, demonstrated by fura-2-associated fluorography, in both arterioles and venules. Cyclo(-D-Trp-D-Asp-Pro-D-Val-Leu-) (BQ123), and endothelin ETA receptor antagonist, at a concentration of 10 microM inhibited the endothelin-3 (100 pM)-induced arteriolar constriction and Ca2+ mobilization in arterioles but not in venules. In venules, an early onset leakage of FITC (fluorescein isothiocyanate)-labeled albumin and subsequent reduction of red blood cell velocity without arteriolar constriction were observed after the superfusion of endothelin-3 with BQ123, suggesting that a non-endothelin ETA receptor mediates macromolecular leakage followed by a decrease in blood flow. Endothelin-3 with BQ123 neither stimulated leukocyte adhesion nor activated luminol-dependent chemiluminescence in venules, showing that endothelin-3-increased permeability may be induced by leukocyte-independent and oxyradical-independent mechanisms. These microvascular alterations of permeability and red blood cell velocity were significantly attenuated by the addition of phalloidin, an F-actin stabilizer, suggesting the involvement of endothelial cell contraction. Nicardipine (1,4-dihydro-2,6-dimethyl-4-[3-nitrophenyl]methyl-2- [methyl(phenylmethyl)amino]-3,5-pyridinedicarboxylic acid ethyl ester), a dihydropyridine-type Ca2+ channel antagonist, eliminated endothelin-3-induced arteriolar constriction; however, it did not affect albumin leakage promoted by endothelin-3 with BQ123, suggesting that a non-voltage-dependent Ca2+ channel(s) is involved in non-endothelin ETA receptor-mediated Ca2+ mobilization and contraction of venular endothelial cells. Overall, it is conceivable that endothelin ETA receptor and voltage-dependent Ca2+ channel are involved in endothelin-3-induced arteriolar constriction. In addition, the present results suggest that Ca2+ mobilization in venular endothelium, which is mediated by a non-endothelin ETA receptor, possibly endothelin ETB receptor and regulated by non-voltage-dependent Ca2+ channel(s), may cause endothelial cell contraction and subsequently increase macromolecular permeability in microvascular beds treated with endothelin-3.
Kurose
I
I
Department of Internal Medicine, School of Medicine, Keio University, Tokyo, Japan.
Miura
S
S
Fukumura
D
D
Tsuchiya
M
M
D000595:Amino Acid Sequence; D000818:Animals; D001783:Blood Flow Velocity / Q000187:drug effects; D002118:Calcium / Q000378:metabolism; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002199:Capillary Permeability / Q000187:drug effects*; D002448:Cell Adhesion / Q000187:drug effects; D065128:Endothelin Receptor Antagonists; D016232:Endothelins / Q000494:pharmacology*; D004730:Endothelium, Vascular / Q000187:drug effects / Q000502:physiology*; D016650:Fluorescein-5-isothiocyanate / Q000031:analogs & derivatives; D007962:Leukocytes / Q000187:drug effects; D008297:Male; D008638:Mesenteric Arteries; D008833:Microcirculation / Q000187:drug effects* / Q000502:physiology; D008969:Molecular Sequence Data; D010456:Peptides, Cyclic / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D012710:Serum Albumin, Bovine; D014661:Vasoconstriction / Q000187:drug effects*
D002121:Calcium Channel Blockers; D065128:Endothelin Receptor Antagonists; D016232:Endothelins; D010456:Peptides, Cyclic; C039217:fluorescein isothiocyanate bovine serum albumin; D012710:Serum Albumin, Bovine; D016650:Fluorescein-5-isothiocyanate; C072247:cyclo(Trp-Asp-Pro-Val-Leu); D002118:Calcium