title: Prostaglandin H2 and thromboxane A2 are contractile factors in intrarenal arteries of spontaneously hypertensive rats.
abstract: Vascular resistance is increased in the kidneys of spontaneously hypertensive rats (SHR). Previous studies have demonstrated impaired vascular relaxations of mesenteric resistance arteries of SHR because of increased production of a cyclooxygenase-dependent endothelium-derived contracting factor. To test the hypothesis that altered endothelial function contributes to the enhanced constriction in kidneys of SHR, endothelium-mediated relaxations of renal resistance arteries from 5-6-week-old prehypertensive SHR and Wistar-Kyoto rats were compared in arteriographs. Acetylcholine induced endothelium-dependent contractions in SHR arteries, while potent endothelium-dependent relaxations were noted in renal arteries from Wistar-Kyoto rats. Inhibition of cyclooxygenase (indomethacin) or blockade of prostaglandin H2-thromboxane A2 receptors (SQ 29,548) blocked acetylcholine-induced contractions in SHR renal arteries; relaxations in SHR renal arteries after either treatment were similar to those observed in renal arteries from Wistar-Kyoto rats. NG-Nitro-L-arginine inhibited acetylcholine-mediated relaxations in both SHR and Wistar-Kyoto arteries. Endothelium-independent relaxations induced by verapamil were comparable in SHR and Wistar-Kyoto arteries. Thus, the impaired response to acetylcholine in SHR renal resistance arteries may result from the release of endothelium-derived cyclooxygenase products (prostaglandin H2 or thromboxane A2), which oppose endothelium-derived nitric oxide-mediated relaxation.
authors.affiliation: Department of Medicine, University of Kansas Medical Center, Kansas City 66103.
authors.forename: F X
authors.initials: FX
authors.lastname: Dai
authors.forename: J
authors.initials: J
authors.lastname: Skopec
authors.forename: A
authors.initials: A
authors.lastname: Diederich
authors.forename: D
authors.initials: D
authors.lastname: Diederich
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D004730:Endothelium, Vascular / Q000502:physiology; D008297:Male; D011450:Prostaglandin Endoperoxides, Synthetic / Q000494:pharmacology*; D044262:Prostaglandin H2; D011463:Prostaglandins H / Q000494:pharmacology*; D051381:Rats; D011918:Rats, Inbred SHR / Q000502:physiology*; D011921:Rats, Inbred WKY; D012077:Renal Artery / Q000187:drug effects*; D013928:Thromboxane A2 / Q000494:pharmacology*; D014662:Vasoconstrictor Agents / Q000494:pharmacology*
chemical_list: D011450:Prostaglandin Endoperoxides, Synthetic; D011463:Prostaglandins H; D014662:Vasoconstrictor Agents; D044262:Prostaglandin H2; D013928:Thromboxane A2