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(Circulation Research. 2009;105:1031.)
© 2009 American Heart Association, Inc.

Clinical/Translational Research

Whole Body UVA Irradiation Lowers Systemic Blood Pressure by Release of Nitric Oxide From Intracutaneous Photolabile Nitric Oxide Derivates

Christian Opländer, Christine M. Volkmar, Adnana Paunel-Görgülü, Ernst E. van Faassen, Christian Heiss, Malte Kelm, Daniel Halmer, Manfred Mürtz, Norbert Pallua, Christoph V. Suschek

From the Department of Plastic and Reconstructive Surgery, Hand Surgery, and Burn Center (C.O., C.M.V., N.P., C.V.S.), Medical Faculty, RWTH Aachen University, Germany; Department of Trauma and Hand Surgery (A.P.-G.), University Hospital Düsseldorf, Germany; Interface Physics (E.E.v.F.), Faculty of Sciences, Utrecht University, The Netherlands; Department of Cardiology and Vascular Medicine (C.H., M.K.), University Hospital Düsseldorf, Germany; and Institute of Laser Medicine (D.H., M.M.), Heinrich-Heine-University of Düsseldorf, Germany.

Correspondence to Dr Christoph V. Suschek, Department of Plastic and Reconstructive Surgery, Hand Surgery, and Burn Center, Medical Faculty, RWTH Aachen University, Pauwelstraße 30, D-52074 Aachen, Germany. E-mail csuschek{at}ukaachen.de

Abstract

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/cm²) 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 ¹⁵N-nitrite, whole body UVA irradiation (20 J/cm²) induced significant levels of ¹⁵N-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 (R²=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.

Key Words: nitric oxide • nitrite • nitroso compounds • UVA • decomposition • photolysis • human skin