title: Vascular response of tumour and normal tissues to endothelin-1 following antagonism of ET(A) and ET(B) receptors in anaesthetised rats.
abstract: Modification of blood flow by endothelin-1 (ET-1) was examined in the s.c. HSN fibrosarcoma and compared to normal tissues of anaesthetised CBH/CBi rats. The ET receptor subtypes involved in the response were investigated using the ET(A) and ET(B) receptor antagonists BQ-610 and BQ-788, respectively. Blood flow and vascular resistance were determined using the uptake of radiolabelled iodo-antipyrine (125I-IAP). BQ-610 or BQ-788 was infused for 30 min prior to blood flow determination. ET-1 was administered 15 min into the infusion time. BQ-610 and BQ-788 infused alone did not modify any vascular parameters. Tumour blood flow increased slightly following ET-1, contrasting with most normal tissues, in which blood flow was reduced. Vascular resistance increased in all tissues, including the tumour. Neither antagonist significantly modified the ET-1-induced changes in tumour blood flow or vascular resistance, whereas in the majority of normal tissues BQ-610 attenuated and BQ-788 potentiated the vascular resonse to ET-1. Our results show that the HSN tumour vasculature is only weakly responsive to ET- 1 and antagonism of its effects by BQ-610 and BQ-788. This contrasts with the majority of normal tissues, in which ET- 1 induces an intense vasoconstriction.
authors.affiliation: Tumour Microcirculation Group, Mount Vernon Hospital, Northwood, UK. bell@graylab.ac.uk
authors.forename: K M
authors.initials: KM
authors.lastname: Bell
authors.forename: V E
authors.initials: VE
authors.lastname: Prise
authors.forename: D J
authors.initials: DJ
authors.lastname: Chaplin
authors.forename: S
authors.initials: S
authors.lastname: Wordsworth
authors.forename: G M
authors.initials: GM
authors.lastname: Tozer
mesh_terms: D000818:Animals; D001783:Blood Flow Velocity / Q000187:drug effects; D001794:Blood Pressure / Q000187:drug effects; D065128:Endothelin Receptor Antagonists; D019332:Endothelin-1 / Q000494:pharmacology*; D005260:Female; D005354:Fibrosarcoma / Q000098:blood supply* / Q000188:drug therapy; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects*; D009374:Neoplasms, Experimental / Q000098:blood supply* / Q000188:drug therapy; D009842:Oligopeptides / Q000494:pharmacology; D010880:Piperidines / Q000494:pharmacology; D051381:Rats; D044022:Receptor, Endothelin A; D044023:Receptor, Endothelin B; D014655:Vascular Resistance / Q000187:drug effects
chemical_list: D065128:Endothelin Receptor Antagonists; D019332:Endothelin-1; D009842:Oligopeptides; D010880:Piperidines; D044022:Receptor, Endothelin A; D044023:Receptor, Endothelin B; C087220:BQ 610; C086539:BQ 788