title: The myogenic response in uremic hypertension.
abstract: BACKGROUND
  The constriction of resistance arteries in response to an increase in transmural pressure, the myogenic response, is thought to be an important determinant of peripheral vascular resistance and therefore of arterial blood pressure. Since raised peripheral resistance is known to occur in uremic hypertension, abnormal myogenic constriction might be responsible. We sought to assess the myogenic response of resistance arteries from the subtotal nephrectomy rat model of uremic hypertension.
  
  
  METHODS
  Uremic Wistar-Kyoto (WKYU) rats, and sham-operated normotensive (WKYC) and spontaneously hypertensive (SHRC) controls were studied in parallel. Skeletal muscle arteries were mounted on a pressure myograph and allowed to develop myogenic constriction. The active internal diameter was measured at increasing lumen pressures from 20 to 200 mm Hg. Vascular smooth muscle then was relaxed in a calcium free solution containing nitroprusside, and the passive internal diameter measured at the same pressure steps. The ratio of active to passive diameter at any given pressure was used to assess the myogenic response.
  
  
  RESULTS
  Myogenic constriction was not increased in either WKYU or SHRC compared to WKYC at pressures up to 180 mm Hg.
  
  
  CONCLUSIONS
  Increased myogenic tone is not the cause of uremic hypertension.
authors.affiliation: Anthony Raine Research Laboratories, St. Bartholomew's Hospital, London, England, United Kingdom. dnew@sghms.ac.uk
authors.forename: David I
authors.initials: DI
authors.lastname: New
authors.forename: Alistair M S
authors.initials: AM
authors.lastname: Chesser
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Raftery
authors.forename: Magdi M
authors.initials: MM
authors.lastname: Yaqoob
mesh_terms: D000818:Animals; D001158:Arteries / Q000503:physiopathology*; D001794:Blood Pressure; D006973:Hypertension / Q000209:etiology* / Q000503:physiopathology*; D066298:In Vitro Techniques; D008297:Male; D018482:Muscle, Skeletal / Q000098:blood supply; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D014511:Uremia / Q000150:complications*; D014661:Vasoconstriction; D014666:Vasomotor System / Q000503:physiopathology*