Microvessel PO2 measurements by phosphorescence decay method

Filho, Ivo P. Torres; Intaglietta, M.

doi:10.1152/ajpheart.1993.265.4.h1434

Cited by 107 publications

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“…PO2 measurements were made using palladium-porphyrin phosphorescence quenching microscopy (21) based on the relationship between the decay rate of excited palladium-mesotetra(4-carboxyphenyl)porphyrin (Porphyrin Products; Logan, UT) bound to albumin and the PO 2 according to the Stern-Volmer equation (35). Animals received a slow intravenous injection of 15 mg/kg body wt (10.1 mg/ml) of the phosphorescence dye ϳ10 min before PO 2 measurements, which provided for an adequate signal-to-noise ratio for interstitial PO2 measurements (21). Simultaneous tissue PO2 measurements using this system and the microelectrode technique have shown nearly identical values (2).…”

Section: Methodsmentioning

confidence: 99%

Oxygen delivery and consumption in the microcirculation after extreme hemodilution with perfluorocarbons

Cabrales¹,

Tsai²,

Frangos³

et al. 2004

American Journal of Physiology-Heart and Circulatory Physiology

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Intaglietta. Oxygen delivery and consumption in the microcirculation after extreme hemodilution with perfluorocarbons. Am J Physiol Heart Circ Physiol 287: H320 -H330, 2004; 10.1152/ajpheart.01166.2003.-The oxygen transport capacity of fluorocarbons was investigated in the hamster chamber window model microcirculation to determine the rate at which oxygen is delivered to the tissue in conditions of extreme hemodilution [hematocrit (Hct) 11%]. Hydroxyethlyl starch (HES 200; 200 kDa molecular mass) was used as a plasma expander for two isovolemic hemodilutions performed with 10% HES 200 until a Hct of 65%. A third step reduced the Hct to 75% of baseline and was performed with either HES 200 or a 60% perfluorocarbon (PFC) emulsion. Comparisons of HES 200-only-hemodiluted animals versus 4.2 g/kg PFC emulsion-hemodiluted animals were made at 21% and 100% normobaric oxygen ventilation. It was found that systemic and microvascular oxygen delivery was 25% and 400% higher in the PFC animals compared with HES 200 animals, respectively, showing that PFCs deliver oxygen to the tissue when combined with hyperoxic ventilation in the present experiments, with no evidence of vasoconstriction or impaired microvascular function. Oxygen ventilation (100%) led to a positive base excess for the PFC group (5.5 Ϯ 2.5 mmol/l) versus a negative balance (Ϫ0.8 Ϯ 1.4 mmol/l) for the HES 200 group, suggesting that microvascular findings corresponded to systemic events. hyperoxia; functional capillary density; oxygen-carrying capacity; blood substitutes; tissue oxygen delivery THE CORRECTION OF BLOOD LOSSES usually begins with the normalization of blood volume. The continued decrease of red blood cell (RBC) concentration is followed by the restoration of oxygen-carrying capacity. To date, this latter phase remains firmly within the purvey of blood transfusion medicine; however, alternative oxygen-carrying volume fluids such as modified hemoglobins (Hbs) and fluorocarbons have emerged in the past decade. Few of these materials have been objectively analyzed in terms of their transport properties at the level of the microscopic blood vessels, where the actual exchange of oxygen takes place, to determine if their properties lead to adequate transport processes at the cellular/tissue level (8).Fluorocarbons have been investigated by different approaches that extended to phase 3 clinical trials (9). These materials carry oxygen, are synthetic, and, in principle, are available in very large quantities at modest costs. This has tantalized investigators, medical practitioners, and business enterprises, because it could, in principle, lead to a convenient, largely available, and pathogen-free oxygen carrier. However, fluorocarbons only become miscible with water when emulsified with phospholipids (derived from egg yolk) and therefore are not completely synthetic. Furthermore, whereas Hb carries oxygen via a reversible chemical reaction, fluorocarbons carry oxygen as a function of their solubility; therefore, at the PO 2 s prevailing in the microcirc...

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Section: Methodsmentioning

confidence: 99%

Oxygen delivery and consumption in the microcirculation after extreme hemodilution with perfluorocarbons

Cabrales¹,

Tsai²,

Frangos³

et al. 2004

American Journal of Physiology-Heart and Circulatory Physiology

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“…Moreover, it is difficult to fix the measurement point, and the spatial resolution is not sufficient for observing micro-vessels. There have been some studies to quantify oxygen tension in micro-vessels optically using phosphorescent intensity and lifetime (6,7). Since the blood flow distribution and pO 2 are closely related in the microcirculation system, a practical system to measure both data simultaneously is very much required.…”

Section: Introductionmentioning

confidence: 99%

Optical Bioimaging: From Living Tissue to a Single Molecule: Imaging and Functional Analysis of Blood Flow in Organic Microcirculation

Minamitani

Tsukada

Sekizuka³

et al. 2003

J Pharmacol Sci

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Abstract. Activity of blood cells, erythrocytes, leucocytes, and platelets, in microcirculation was observed by using an intravital microscope and confocal laser scanning microscope connected with an image processing system including fluorescence and phosphorescence emission methods. Dynamic functions of the blood flow were mainly observed in mesentery, brain, and liver tissues of rats. The results are summarized as follows: Deformability of diabetic erythrocytes was significantly lower than that of healthy controls, particularly at high shear rate. The spring constant and Young's modulus of diabetic erythrocytes obviously stiffened, making them hard to deform in the capillary. During hemorrhagic shock and thrombosis, flow velocity and oxygen partial pressure of blood decreased in the brain and liver tissues that can be visualized by using FITC stained erythrocytes and Pd-porphyrin derivative as a pO 2 probe. Platelet adhesion and thrombus formation in the micro-vessels accelerated under the photodynamic reaction; diabetic platelets showed augmented adhesion and aggregation on the vessel wall which was followed by acute thromboembolism. Active oxygen radicals take part in thrombus formation, accompanied with adhesion of the activated leucocytes. Fluorescent dye probes, rhodamine G and acridine orange, are quite useful for visualization of the flow behavior of platelets and leucocytes, respectively.

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“…Noninvasive measurement of PO 2 can be obtained using phosphorescence signals from a metalloporphyrin probe (8). Using a new investigating tool, Torres Filho et al (9,10) measured intravascular and extravascular PO 2 in small tissue areas. This PO 2 measurement system has been implemented also in other laboratories (6,11).…”

mentioning

confidence: 99%

“…The technique has been described in detail previously (9,10). Briefly, palladium (Pd)-meso-tetra (4-carboxyphenyl) porphine (Porphyrin Products, Inc., Logan, UT, USA) previously bound to albumin was used as a probe.…”

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Determination of macromolecular exchange and PO2 in the microcirculation: a simple system for in vivo fluorescence and phosphorescence videomicroscopy

Torres

Filho

2001

Braz J Med Biol Res

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We have developed a system with two epi-illumination sources, a DCregulated lamp for transillumination and mechanical switches for rapid shift of illumination and detection of defined areas (250-750 µm 2 ) by fluorescence and phosphorescence videomicroscopy. The system permits investigation of standard microvascular parameters, vascular permeability as well as intra-and extravascular PO 2 by phosphorescence quenching of Pd-meso-tetra (4-carboxyphenyl) porphine (PORPH). A Pechan prism was used to position a defined region over the photomultiplier and TV camera. In order to validate the system for in vivo use, in vitro tests were performed with probes at concentrations that can be found in microvascular studies. Extensive in vitro evaluations were performed by filling glass capillaries with solutions of various concentrations of FITC-dextran (diluted in blood and in saline) mixed with different amounts of PORPH. Fluorescence intensity and phosphorescence decay were determined for each mixture. FITC-dextran solutions without PORPH and PORPH solutions without FITC-dextran were used as references. Phosphorescence decay curves were relatively unaffected by the presence of FITC-dextran at all concentrations tested (0.1 µg/ml to 5 mg/ml). Likewise, fluorescence determinations were performed in the presence of PORPH (0.05 to 0.5 mg/ml). The system was successfully used to study macromolecular extravasation and PO 2 in the rat mesentery circulation under controlled conditions and during ischemia-reperfusion.

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Microvessel PO2 measurements by phosphorescence decay method

Cited by 107 publications

References 0 publications

Oxygen delivery and consumption in the microcirculation after extreme hemodilution with perfluorocarbons

Oxygen delivery and consumption in the microcirculation after extreme hemodilution with perfluorocarbons

Optical Bioimaging: From Living Tissue to a Single Molecule: Imaging and Functional Analysis of Blood Flow in Organic Microcirculation

Determination of macromolecular exchange and PO2 in the microcirculation: a simple system for in vivo fluorescence and phosphorescence videomicroscopy

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