Document Detail

Photochemical oxygen consumption sensitized by a porphyrin phosphorescent probe in two model systems.
MedLine Citation:
PMID:  10777756     Owner:  NLM     Status:  MEDLINE    
Phosphorescence quenching of certain metalloporphyrins is used to measure tissue and microvascular pO(2). Oxygen quenching of metalloporphyrin triplet states creates singlet oxygen, which is highly reactive in biological systems, and these oxygen-consuming reactions are capable of perturbing tissue oxygenation. Kinetics of photochemical oxygen consumption were measured for a Pd-porphyrin in two model systems in vitro over a range of irradiances (1.34-134 mW cm(-2)). For a given irradiance, and, after correction for differing porphyrin concentrations, rates of oxygen consumption were similar when the Pd-porphyrin was bound to bovine serum albumin and when it was taken up by tumor cells in spheroids. At irradiances comparable to those used in imaging superficial anatomy, rates of oxygen consumption were sufficiently low (2.5 microM s(-1)) that tissue oxygenation would be reduced by a maximum of 6%. An irradiance of 20 mW cm(-2), however, initiated a rate of oxygen consumption capable of reducing tissue pO(2) by at least 20-40%. These measured rates of consumption impose limitations on the use of phosphorescence quenching in thick tissues. The irreversible photobleaching of the Pd-porphyrin was also measured indirectly. The bleaching branching ratio, 23 M(-1), is significantly lower than that of porphyrin photodynamic agents.
S Mitra; T H Foster
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Publication Detail:
Type:  In Vitro; Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Biophysical journal     Volume:  78     ISSN:  0006-3495     ISO Abbreviation:  Biophys. J.     Publication Date:  2000 May 
Date Detail:
Created Date:  2000-06-26     Completed Date:  2000-06-26     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  0370626     Medline TA:  Biophys J     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  2597-605     Citation Subset:  IM    
Department of Biochemistry, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642 USA.
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MeSH Terms
Biophysical Phenomena
Fluorescent Dyes
Models, Biological
Oxygen Consumption*
Serum Albumin, Bovine
Spheroids, Cellular
Grant Support
Reg. No./Substance:
0/Fluorescent Dyes; 0/Porphyrins; 0/Serum Albumin, Bovine

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