Whole body UVA irradiation lowers systemic blood pressure by release of nitric oxide from intracutaneous photolabile nitric oxide derivates

Circ Res. 2009 Nov 6;105(10):1031-40. doi: 10.1161/CIRCRESAHA.109.207019. Epub 2009 Sep 24.


Rationale: Human skin contains photolabile nitric oxide derivates like nitrite and S-nitroso thiols, which after UVA irradiation, decompose and lead to the formation of vasoactive NO.

Objective: Here, we investigated whether whole body UVA irradiation influences the blood pressure of healthy volunteers because of cutaneous nonenzymatic NO formation.

Methods and results: As detected by chemoluminescence detection or by electron paramagnetic resonance spectroscopy in vitro with human skin specimens, UVA illumination (25 J/cm(2)) significantly increased the intradermal levels of free NO. In addition, UVA enhanced dermal S-nitrosothiols 2.3-fold, and the subfraction of dermal S-nitrosoalbumin 2.9-fold. In vivo, in healthy volunteers creamed with a skin cream containing isotopically labeled (15)N-nitrite, whole body UVA irradiation (20 J/cm(2)) induced significant levels of (15)N-labeled S-nitrosothiols in the blood plasma of light exposed subjects, as detected by cavity leak out spectroscopy. Furthermore, whole body UVA irradiation caused a rapid, significant decrease, lasting up to 60 minutes, in systolic and diastolic blood pressure of healthy volunteers by 11+/-2% at 30 minutes after UVA exposure. The decrease in blood pressure strongly correlated (R(2)=0.74) with enhanced plasma concentration of nitrosated species, as detected by a chemiluminescence assay, with increased forearm blood flow (+26+/-7%), with increased flow mediated vasodilation of the brachial artery (+68+/-22%), and with decreased forearm vascular resistance (-28+/-7%).

Conclusions: UVA irradiation of human skin caused a significant drop in blood pressure even at moderate UVA doses. The effects were attributed to UVA induced release of NO from cutaneous photolabile NO derivates.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Blood Pressure / radiation effects*
  • Dose-Response Relationship, Radiation
  • Female
  • Humans
  • Male
  • Middle Aged
  • Nitric Oxide / blood*
  • Nitrites / blood*
  • Nitroso Compounds / blood*
  • Skin / metabolism*
  • Time Factors
  • Ultraviolet Rays*


  • Nitrites
  • Nitroso Compounds
  • Nitric Oxide