species, as detected by a chemiluminescence assay, with increased forearm blood flow (267%), with increased flow mediated vasodilation of the brachial artery (6822%), and with decreased forearm vascular resistance (287%). 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. (Circ Res. 2009;105:1031-1040.)

Christian Heiss, Malte Kelm, Daniel Halmer, Manfred Mürtz, Norbert Pallua and Christoph V. Christian Opländer, Christine M. Volkmar, Adnana Paunel-Görgülü, Ernst E. van Faassen, From Intracutaneous Photolabile Nitric Oxide Derivates Whole Body UVA Irradiation Lowers Systemic Blood Pressure by Release of Nitric Oxide Print ISSN: 0009-7330. Online ISSN: 1524-4571 Copyright © 2009 American Heart Association, Inc. All rights reserved. is published by the American Heart Association, 7272 Greenville Avenue, Dallas, TX 75231 Circulation Research doi: 10.1161/CIRCRESAHA.109.207019 2009;105:1031-1040; originally published online September 24, 2009; Circ Res. http://circres.ahajournals.org/content/105/10/1031 World Wide Web at: The online version of this article, along with updated information and services, is located on the http://circres.ahajournals.org/content/suppl/2009/09/24/CIRCRESAHA.109.207019.DC1.html Data Supplement (unedited) at:

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.

Comparison of two different methods for the measurement of ethane at the parts-per-billion (ppb) level is reported. We used cavity leak-out spectroscopy (CALOS) in the 3 microm wavelength region and gas chromatography-flame ionization detection (GC-FID) for the analysis of various gas samples containing ethane fractions in synthetic air. Intraday and interday reproducibilities were studied. Intercomparing the results of two series involving seven samples with ethane mixing ratios ranging from 0.5 to 100 ppb, we found a reasonable agreement between both methods. The scatter plot of GC-FID data versus CALOS data yields a linear regression slope of 1.07 +/- 0.03. Furthermore, some of the ethane mixtures were checked over the course of 1 year, which proved the long-term stability of the ethane mixing ratio. We conclude that CALOS shows equivalent ethane analysis precision compared to GC-FID, with the significant advantage of a much higher time resolution (<1 s) since there is no requirement for sample preconcentration. This opens new analytical possibilities, e.g., for real-time monitoring of ethane traces in exhaled human breath.