title: Endothelin-1 in human skin: immunolocalization, receptor binding, mRNA expression, and effects on cutaneous microvascular endothelial cells.
abstract: Endothelin-1 (ET-1), a potent vasoconstrictor peptide, has been implicated in the maintenance of systemic and peripheral vascular tone. We have therefore sought direct evidence of a role for ET-1 in the regulation of blood flow and vascular tone in the human cutaneous microvasculature. Immunostaining for ET-1 was observed in all cutaneous blood vessels of normal human skin including the capillaries of the dermal papillae. Autoradiography showed specific binding of 125I-ET-1 over capillaries and larger blood vessels as well as hair follicles and sweat glands. In situ hybridization with a 32P-labeled RNA probe for ET-1 demonstrated mRNA for ET-1 in cultured human dermal microvascular endothelial cells (HDMEC). In HDMEC, basal release of PGE2 was significantly attenuated by ET-1 (100 pM-100 nM) (p less than 0.05, n = 7) with maximum inhibition in cells incubated with 10 nM ET-1. ET-1 also increased intracellular cAMP in a dose-dependent manner with a significant increase in HDMEC incubated with 100 nM ET-1 (p less than 0.05, n = 4). In HDMEC incubated with 100 nM ET-1, inhibition of PGE2 release was unaffected by the dihydropyridine Ca++ channel antagonist nifedipine or the extracellular Ca++ chelator EGTA, whereas the intracellular Ca++ chelator TMB-8 partially blocked the action of ET-1. In contrast, cAMP accumulation was significantly attenuated by EGTA (p less than 0.05, n = 4), nifedipine (p less than 0.05, n = 4), and TMB-8 (p less than 0.05, n = 4), indicating that the endothelial cell responses to ET-1 are complex and appear to involve both Ca(++)-sensitive and -insensitive pathways. These results provide evidence of an autocrine/paracrine role for ET-1 in the human cutaneous microvasculature.
authors.affiliation: Department of Dermatology, University College, Middlesex School of Medicine, London, U.K.
authors.forename: H A
authors.initials: HA
authors.lastname: Bull
authors.forename: C B
authors.initials: CB
authors.lastname: Bunker
authors.forename: G
authors.initials: G
authors.lastname: Terenghi
authors.forename: D R
authors.initials: DR
authors.lastname: Springall
authors.forename: Y
authors.initials: Y
authors.lastname: Zhao
authors.forename: J M
authors.initials: JM
authors.lastname: Polak
authors.forename: P M
authors.initials: PM
authors.lastname: Dowd
mesh_terms: D002118:Calcium / Q000502:physiology; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism; D015232:Dinoprostone / Q000378:metabolism; D016232:Endothelins / Q000032:analysis* / Q000378:metabolism / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000378:metabolism; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D012333:RNA, Messenger / Q000032:analysis*; D011956:Receptors, Cell Surface / Q000378:metabolism*; D017466:Receptors, Endothelin; D012867:Skin / Q000737:chemistry*
chemical_list: D016232:Endothelins; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D017466:Receptors, Endothelin; D000242:Cyclic AMP; D015232:Dinoprostone; D002118:Calcium