title: Photophysical characterisation and studies of the effect of palladium(II) 5,10,15,20-tetrakis-(4-sulfonatophenyl)-porphyrin on isometric contraction of isolated human mesenteric artery: good news for photodynamic therapy.
abstract: BACKGROUND
  Considering the important roles of porphyrins in biological systems and their promising use in photodynamic therapy (PDT), the present work investigated the photophysical properties of palladium(II) 5,10,15,20-tetrakis-(4-sulfonatophenyl)-porphyrin (PdTSPP) and the effects of non-activated by light form of this porphyrin on contractile behaviour of isolated healthy endothelium-denuded human mesenteric arteries.
  
  
  METHODS
  The photophysical characterisation of PdTSPP: the formation of the triplet states and the singlet oxygen were studied using laser flash photolysis. The effect of PdTSPP on the isometric contraction of artery segments from human mesentery was assessed utilising the precise method of artery isometric tension recording using Mulvany-Halpern wire myograph.
  
  
  RESULTS
  We found that PdTSPP had a high lifetime of the triplet states τT=270μs. The calculated Stern Volmer rate constant kq=1.7×10(9)M(-1)s(-1) showed an efficient quenching by oxygen that indicated formation of singlet oxygen, O2((1)Δg). The photophysical parameters of PdTSPP, in particular its ability to generate O2((1)Δg) has defined it as an exceptionally interesting molecule for PDT. The results of the contraction study showed that PdTSPP applied in increasing concentrations (1-100μM) had no effect on the basal tone of human mesenteric artery under isometric condition. Furthermore, PdTSPP failed to potentiate or to attenuate the isometric contraction of the artery preparations precontracted with high extracellular potassium (42mM KCl) or with 1nM endothelin-1.
  
  
  CONCLUSIONS
  The excellent photophysical properties of PdTSPP as well as the lack of an effect on the contractility of human vasculature in vitro characterise PdTSPP as a suitable compound for potential medical applications.
authors.affiliation: Department Excitable Structures, Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Acad. G. Bonchev Street, Bldg. 21, 1113, Sofia, Bulgaria. Electronic address: daniadim@yahoo.com.
authors.forename: Daniela Z
authors.initials: DZ
authors.lastname: Dimitrova
authors.affiliation: J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejškova 3, 182 23 Praha 8, Czech Republic.
authors.forename: Pavel
authors.initials: P
authors.lastname: Kubat
authors.affiliation: Department of Anesthesiology and Intensive Care, Military Medical Academy, Sveti Georgi Sofiyski Street 3, 1606 Sofia, Bulgaria.
authors.forename: Stanislav
authors.initials: S
authors.lastname: Dimitrov
authors.affiliation: Department of Surgery, Military Medical Academy, Sveti Georgi Sofiyski Street 3, 1606, Sofia, Bulgaria.
authors.forename: Evgeni
authors.initials: E
authors.lastname: Belokonski
authors.affiliation: Department Molecular Biology of Cell Cycle, Institute of Molecular Biology, Bulgarian Academy of Sciences, Acad. G. Bonchev Street, bl. 21, 1113 Sofia, Bulgaria.
authors.forename: Vanya
authors.initials: V
authors.lastname: Bogoeva
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D007537:Isometric Contraction / Q000187:drug effects / Q000502:physiology*; D008297:Male; D008638:Mesenteric Arteries / Q000187:drug effects / Q000502:physiology*; D008875:Middle Aged; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology*; D010778:Photochemotherapy / Q000379:methods; D011166:Porphyrins / Q000008:administration & dosage*; D011838:Radiation-Sensitizing Agents / Q000008:administration & dosage; D014655:Vascular Resistance / Q000187:drug effects / Q000502:physiology*
chemical_list: C410940:5,10,15,20-tetrakis(4-sulfonatophenyl)-21,23-dithiaporphyrin; D011166:Porphyrins; D011838:Radiation-Sensitizing Agents
keywords: Human mesenteric artery; Isometric contraction; Laser kinetics; Palladium(II) 5,10,15,20-tetrakis-(4-sulfonatophenyl)-porphyrin; Photophysical properties