A photoactivable source of relaxing factor in genetic hypertension

John R. Charpie, Anthony Peters, R. Clinton Webb

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


Deendothelialized rings of rabbit aorta relax after exposure to UV light because of release of a relaxing factor that is similar if not identical to nitric oxide. We tested the hypothesis that production of the photo-induced relaxing factor is impaired in a rat model of genetic hypertension. Thoracic aortas were removed from adult Wistar-Kyoto rats and stroke-prone spontaneously hypertensive rats. The vessels were cut into rings, denuded of endothelium, and placed in a muscle bath for isometric force measurement. Rings were contracted with phenylephrine, and relaxation was measured after exposure to UV light. Aortic rings from stroke-prone spontaneously hypertensive rats relaxed to a greater extent after exposure to UV light than did rings from Wistar-Kyoto rats. An inhibitor of nitric oxide synthase -nitro-L-arginine) greatly potentiated the relaxation responses to light in both strains, and these enhanced relaxations were attenuated by tetraethylammonium chloride, potassium chloride, ouabain, or inhibitors of guanylate cyclase. These results suggest that UV irradiation induces relaxation in aortic smooth muscle that is greater in hypertensive than normotensive rats and is greatly enhanced after addition of inhibitors of nitric oxide production. Thus, the unidentified photo-induced relaxing factor is not solely nitric oxide but may also represent either a hyperpolarizing factor, because depolarization blocks the responses entirely, or possibly smooth muscle guanylate cyclase that might itself be photoactivable.

Original languageEnglish (US)
Pages (from-to)894-898
Number of pages5
Issue number6
StatePublished - Jun 1994


  • Aorta
  • Genetic
  • Hypertension
  • Muscle
  • Nitric oxide
  • Smooth
  • Ultraviolet rays
  • Vascular

ASJC Scopus subject areas

  • Internal Medicine


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