title: Endothelin receptor A blockade alters hemodynamic response to nitric oxide inhibition in rats.
abstract: We examined the extent to which the systemic and renal vasoconstriction induced by nitric oxide (NO) inhibition in vivo is mediated by endothelin (ET). We examined the effects of BQ-610, a specific ETA-receptor antagonist, after NO inhibition with N omega-nitro-L-arginine methyl ester (L-NAME) in the anesthetized rat. Mean arterial pressure (MAP) increased after L-NAME infusion from 107 +/- 2 to 133 +/- 3 mmHg (P < 0.05 vs. baseline period) then fell to 115 +/- 3 mmHg after administration of BQ-610 (P < 0.05 vs. L-NAME and baseline periods). Systemic vascular resistance (SVR) increased from 1.26 +/- 0.06 to 2.17 +/- 0.18 mmHg.ml-1.min.300 g after L-NAME (P < 0.05 vs. baseline period) then fell to 1.69 +/- 0.12 mmHg.ml-1.min.300 g after BQ-610 (P < 0.05 vs. L-NAME and baseline periods). The increase in renal vascular resistance (RVR) from 6.4 +/- 0.4 to 13.7 +/- 1.4 mmHg.ml-1.min.300 g induced by L-NAME (P < 0.05 vs. baseline period) was reduced to 11.1 +/- 1.0 mmHg.ml-1.min.300 g by BQ-610 (P < 0.05 vs. L-NAME and baseline periods). The extent to which BQ-610 reversed the L-NAME-induced increases in RVR and SVR was comparable (RVR by 40 +/- 9%; SVR by 52 +/- 7%). Glomerular filtration rate and renal blood flow were both reduced by L-NAME, but neither value increased after BQ-610, possibly because the renal vasodilation induced by ETA blockade was offset by the concomitant reduction in MAP and renal perfusion pressure.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Evans Memorial Department of Clinical Research, Boston University Medical Center, Massachusetts 02118, USA.
authors.forename: A
authors.initials: A
authors.lastname: Thompson
authors.forename: C R
authors.initials: CR
authors.lastname: Valeri
authors.forename: W
authors.initials: W
authors.lastname: Lieberthal
mesh_terms: D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects; D065128:Endothelin Receptor Antagonists; D006439:Hemodynamics / Q000187:drug effects; D008297:Male; D019331:NG-Nitroarginine Methyl Ester; D009569:Nitric Oxide / Q000037:antagonists & inhibitors*; D009842:Oligopeptides / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012079:Renal Circulation / Q000187:drug effects
chemical_list: D065128:Endothelin Receptor Antagonists; D009842:Oligopeptides; C087220:BQ 610; D009569:Nitric Oxide; D001120:Arginine; D019331:NG-Nitroarginine Methyl Ester