Daniela Z Dimitrova1, Pavel Kubat2, Stanislav Dimitrov3, Evgeni Belokonski4, Vanya Bogoeva5. 1. 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. 2. J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejškova 3, 182 23 Praha 8, Czech Republic. 3. Department of Anesthesiology and Intensive Care, Military Medical Academy, Sveti Georgi Sofiyski Street 3, 1606 Sofia, Bulgaria. 4. Department of Surgery, Military Medical Academy, Sveti Georgi Sofiyski Street 3, 1606, Sofia, Bulgaria. 5. Department Molecular Biology of Cell Cycle, Institute of Molecular Biology, Bulgarian Academy of Sciences, Acad. G. Bonchev Street, bl. 21, 1113 Sofia, Bulgaria.
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.
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.