Liposomes as carriers of resveratrol and vitamin E: Evaluating ameliorative antioxidant effect using chemical and cellular test systems.

Resveratrol (RES) in combination with antioxidant vitamins is reported to be more effective in protecting the cells from oxidative stress rather than any of these antioxidants alone. In continuation to our previous work using resveratrol and vitamin C, our main aim was to evaluate the antioxidant restorative effect using chemical and cellular test systems on resveratrol co-encapsulated vitamin E (VE) within liposomes. Z-average size was less than 135 nm, polydispersity index < 0.3; zeta potential > than ± 30 mV and encapsulation efficiency of RES and VE > 90% and 79% respectively. Chemiluminescence measurement indicated that the antioxidative activity of RES could be increased when VE was additionally loaded into liposomes. Inhibition of AAPH induced luminol enhanced chemiluminescence displayed 90% improvement (P < 0.001) in comparison to control; on the other hand 70% luminescence inhibition of ROS production in isolated blood leukocytes (P < 0.001) was observed. Intracellular oxygen-derived radicals measured by flow cytometry using 2'-7'-dichlorodihydrofluorescein diacetate demonstrated about 1.7 fold (P < 0.05) and 1.5 fold (P < 0.001) enhancement of radical scavenging activity in buffy coats under basal conditions and human umbilical vein endothelial cells after stimulation by H2O2 respectively. The cellular systems evidenced the ability of liposome loaded antioxidants to scavenge ROS in the extra and intracellular space, confirming enhanced antioxidative effectivity of RES in the presence of VE, which did not occur in combination with vitamin C. Hence it might be possible to improve the antioxidative effectivity of RES by other/additional antioxidants.

The Role of Potassium Channels in the Vasodilatation Induced by Resveratrol and Naringenin in Isolated Human Umbilical Vein.

Preclinical Research Potassium (K+ ) channels have a key role in the maintenance of smooth muscle tone; a variety of agonists can modify the tone by altering K+ -channel activity. The aim of this study was assess the effects of the phenols, resveratrol, and naringenin on K+ -channels of the vascular smooth muscle. Segments of human umbilical vein (HUV) without endothelium were precontracted using serotonin (100 µM) or 100 mM K+ to derive cumulative concentration-response curves using increasing concentrations of resveratrol or naringenin. K+ -channel inhibitors were added in the bath before resveratrol (1-100 µM) or naringenin (0.01-1 mM) in assess the role of K+ -channels in their effects on HUV precontracted by serotonin. 4-Aminopiridine (4-AP; 1 mM), a nonselective blocker of voltage-dependent, tetraethylammonium (TEA; 1 mM) and barium chloride (1 mM), a nonselective blocker of Ca2+ -dependent and inward rectifier K+ -channels (respectively) induced significant shifts to the right (P < 0.05) of resveratrol. concentration-response curves. The effect of naringenin was antagonized by 4-AP (1 mM). 4-AP-, TEA-, and barium chloride-sensitive K+ -channels are probably involved in the resveratrol vasodilatatory effect, while naringenin seems to affect 4-AP-sensitive K+ -channels. However, other mechanisms of vasodilation induced by polyphenols could not be excluded. Drug Dev Res, 2015. © 2015 Wiley Periodicals, Inc.

The different effects of resveratrol and naringenin on isolated human umbilical vein: the role of ATP-sensitive K⁺ channels.

The blood flow from the placenta to the fetus depends on human umbilical vein (HUV) vascular tone. ATP-sensitive K(+) (K(ATP)) channels link the metabolic state of the cell to membrane potential, and their activation in the HUV represents protection against hypoxia. The aims of our study were to assess the effects of resveratrol and naringenin on the HUV and to define the roles of K(ATP) channels in their effects. Serotonin or 100 mM K(+) were used for precontraction of the HUV without endothelium. The cumulative concentration-response curves were obtained by adding increasing concentrations of resveratrol or naringenin. Glibenclamide was used, in order to test the role of K(ATP) channels in its effect. Resveratrol induced more potent vasodilatation of serotonin- and 100 mM K(+)-precontracted HUV than naringenin. Glibenclamide induced significant shift to the right of the concentration-response curves of resveratrol and P1075 (a specific opener of K(ATP) channels). Western blotting showed that HUV expressed protein Kir6.1. Thus, resveratrol and naringenin produce dilatation of HUV. It seems that K(ATP) channels are involved in the relaxation of HUV induced by resveratrol, while naringenin seems to interact with other ion channels. The K(+) channel-independent mechanism(s) of these polyphenols could not be excluded.

Effect of wine polyphenol resveratrol on the contractions elicited electrically or by norepinephrine in the rat portal vein.

We investigated the effects of resveratrol on rat portal vein (RPV) contractility without endothelium. Contractions were produced by electrical field stimulation of perivascular nerves (EFS), norepinephrine (NE), adenosine 5'-triphosphate (ATP), high K(+) solution and by calcium chloride (CaCl2 ) in Ca(2+) -free and high K(+) , Ca(2+) -free solution. The EFS-evoked contractions were more sensitive to resveratrol and to NS1619-selective openers of big calcium-sensitive (BKCa ) channels, than NE-evoked contractions. Effects of resveratrol on the ATP-evoked contractions were weak. Blockers of BKCa channels partly inhibited the effect of resveratrol only in EFS-contracted preparations. Western blotting showed that RPV expressed KCa 1.1 protein. Inhibitors of ATP- and voltage-sensitive K(+) channels did not modify the effects of resveratrol. None of the antagonists of K(+) channels affected the resveratrol inhibition of NE-evoked contractions and effect of high concentrations of resveratrol on the EFS-evoked contractions. Resveratrol more potently inhibited CaCl2 than potassium chloride contractions of RPV. Thus, BKCa channels partly mediate the inhibitory effect of resveratrol on the neurogenic contractions of RPV. The smooth muscle Ca(2+) channels and/or Ca(2+) mobilizing through cells might be involved in the effects of resveratrol on the contractility of RPV. Our results are important for better understanding the impact of resveratrol on the portal circulation.

The effects of potassium channel opener P1075 on the human saphenous vein and human internal mammary artery.

Because adrenergic contractions can contribute to the development of life-threatening spasm of coronary artery bypass graft, this study was performed to investigate the effect of adenosine 3-phosphate (ATP)-sensitive K channel (KATP) opener P1075 on contractions of isolated human saphenous vein (HSV) and human internal mammary artery (HIMA). Phasic contractions were evoked by electric field stimulation (20 Hz) and noradrenaline. The sustained contractions were evoked by phenylephrine. The presence of pore-forming Kir6.1 and Kir6.2 subunits of the KATP channels in the HIMA and only Kir6.2 in the HSV was confirmed immunomorphologically. P1075 inhibited in the HSV only, the electrical field stimulation contractions more strongly than noradrenaline contractions. In addition, the phenylephrine contractions of HSV were more sensitive to P1075 in comparison to those of HIMA. Glibenclamide, a KATP channel blocker antagonized the vasodilatation produced by P1075 in both grafts differently, because its effect was more prominent on the P1075-induced inhibition of contractions of HSV than of HIMA. We conclude that P1075 has a vasorelaxant effect and inhibited adrenergic contractions of the tested grafts. This effect is graft and vasoconstrictor selective and seems to be mediated by Kir6.1- and/or Kir6.2-containing KATP channels. Thus, P1075 can be considered as a potential drug in the prevention of graft spasm.

Effects of hydroperoxides on contractile reactivity and free radical production of porcine brain arteries.

Hydroperoxide-induced oxidative stress is assumed to be involved in vasospasm of cerebral arteries after subarachnoid hemorrhage. In order to study underlying mechanisms the effects of H2O2 and tert butylhydroperoxide on contractile functions as well as on free radical production of anterior cerebral artery from pig were investigated. The hydroperoxides increased in a similar dose-dependent arterial contraction, however, the underlying mechanisms involve impairment of endothelial-dependent relaxation as well as of smooth muscle contractile function as shown by experiments with inhibited endothelial NO-synthesis. Determination of lucigenine detectable O2(-)-release showed rather low values with both hydroperoxides, whereas, in comparison, the unspecific luminol-dependent chemi-luminescence was increased up to 1000-fold, especially by H2O2. In conclusion it was shown that application of the hydroperoxides resulted in increased contraction of cerebral arteries, yet that the underlying mechanisms altering function of endothelial and smooth muscle cells need further exploration.

Increased gene expression of scavenger receptors and proinflammatory markers in peripheral blood mononuclear cells of hyperlipidemic males.

Interactions between peripheral blood mononuclear cells (PBMCs) and those within plaques are suggested to be pathophysiologically relevant to lipid-induced arteriosclerosis. In this study, gene expressions of scavenger receptors (CD36, CD68), LPS receptor (CD14), proinflammatory (tumor necrosis factor alpha [TNFalpha], CD40, interleukin-1 beta [IL-1beta]) and oxidative stress-related (manganese superoxide dismutase [MnSOD]) markers were analyzed in PBMCs of clinically asymptomatic males with classical proatherogenic risk factors such as smoking and/or hyperlipidemia. PBMCs were isolated from venous blood of normolipidemic non-smokers (n = 10) and smokers (n = 8), and hyperlipidemic non-smokers (n = 9) and smokers (n = 8). RNA from PBMCs was used for PCR analyses. Plasma concentrations of oxidized low-density lipoproteins (oxLDL) were measured by ELISA. The gene expressions of CD36, CD68, CD40, TNFalpha, and MnSOD were significantly higher in PBMCs of hyperlipidemics than in normolipidemics, irrespective of whether they were smoking or not. The individual expression of these genes showed significant positive correlations with each other but also with serum cholesterol or plasma oxLDL concentrations. The higher expressions of scavenger receptors, proinflammatory and oxidative stress-related genes of PBMCs are suggested to result mainly from hyperlipidemia and the accompanied increase of oxLDL concentrations.

The effect of potassium channel opener pinacidil on the non-pregnant rat uterus.

The effects of the K(+) channel opener, pinacidil on the spontaneous rhythmic contractions and contractions provoked by electrical field stimulation (50 Hz) or by oxytocin were investigated in the isolated uterus of the non-pregnant rat in oestrus. Pinacidil produced more potent inhibition of oxytocin-elicited contractions than of spontaneous rhythmic contractions or electrical field stimulation-induced contractions. Glibenclamide, a selective blocker of adenosine triphosphate (ATP)-sensitive K(+) (K(ATP)) channels, antagonized the pinacidil-induced inhibition of contractions elicited by oxytocin in a competitive manner. However, the pinacidil-induced inhibition of electrical field stimulation-elicited contractions and spontaneous rhythmic contractions was antagonized non-competitively by glibenclamide. In the uterine strips pre-contracted with 80 mM K(+), the pinacidil-induced maximal relaxation was not affected. The present data show that pinacidil exhibits potent relaxant properties in the rat non-pregnant uterus in oestrus and therefore should be taken into account as a possible agent for treatment of dysmenorrhoea. Based on glibenclamide affinity, it appears that the inhibitory response to pinacidil involves K(ATP )channels. We need further investigations to explain why the interaction between glibenclamide and pinacidil in this experimental model depends on the nature of contractions. The ability of pinacidil to completely relax the rat non-pregnant uterus pre-contracted with K(+)-rich solution suggests that K(+) channel-independent mechanism(s) also play a part in its relaxant effect.

Potassium channels-mediated vasorelaxation of rat aorta induced by resveratrol.

Resveratrol, a phenolic substance present in grapes and a variety of medical plants, has been reported to induce vasorelaxation, however the mechanisms are uncertain. In this paper we investigate the possible participation of K(+) channels in the endothelium-independent vasodilatation of rat aorta induced by resveratrol. Resveratrol induced concentration-dependent relaxation of rings with endothelium and without endothelium. We used different potassium channel inhibitors to determine whether the K(+) channels mediated endothelium-independent relaxation of rat aorta induced by resveratrol. Highly selective blocker of ATP-sensitive K(+) channels, glibenclamide, as well as non-selective blockers of K(+) channels, tetraethylammonium, did not block resveratrol-induced relaxation of rat aortic rings. Charybdotoxin, a blocker of calcium-sensitive K(+) channels did not affect the resveratrol-induced relaxation. 4-Aminopiridine, non-selective blocker of voltage-gated K(+) (Kv) channels, and margatoxin that inhibits Kv1 channels abolished relaxation of rat aortic rings induced by resveratrol. In conclusion, we have shown that resveratrol potently relaxed rat aortic rings with denuded endothelium. It seems that 4-aminopiridine and margatoxin-sensitive K(+) channels located in the smooth muscle of rat aorta mediated this relaxation.

Effect of inhibitors of myeloperoxidase on the development of aortic atherosclerosis in an animal model.

Our earlier studies have shown that some steroids increase myeloperoxidase enzyme (MPO) release from human granulocytes, and that MPO plasma levels are significantly lower in postclimacteric people. Moreover, we have proven that MPO inhibits production of atherogenic free radical superoxide anion and MPO-inhibitors increase superoxide release. The aim of the present study was to investigate the effect of MPO-inhibitors on the early phase of aortic atherosclerosis, namely the extent of intimal plaques and the thickening of the medial layer. Adult male rabbits were fed with lipid rich food (cholesterol: 1.3%, peanut oil: 8%) for 8 weeks. During this period MPO-inhibitors were also given (4-aminobenzoicacid-hydrazide/ABAH/-13.3 mg/kg/day or indometacin-5 mg/kg/day). All animals developed intimal lipid plaques (raised fatty streaks). The relative plaque-covered areas of the aortas were compared and the media thickness of the aorta was measured on plaque-free as well as plaque-containing areas. The medial smooth muscle density and peroxidase activity of the aortic media were also determined. The media thickness increased (p<0.05) in the cholesterol+ABAH as well as in the cholesterol+indometacin groups up to 375.7 (+/-60.5) and 442.5 (+/-123.4) microm, respectively, compared to the control group (cholesterol feeding alone) where it measured only 308.4 (+/-51.67) microm. The medial peroxidase activity decreased significantly in the indometacin treated group and showed a decreasing tendency using ABAH. In parallel to this there was a tendency of increase in the relative plaque covered areas. The smooth muscle density showed no significant modifications, while inhibitors of the MPO seemed to enhance aortic medial thickness, i.e. the grade of a pre-atherosclerotic lesion, in our animal model. Collectively, the anti-atherogenic effect of certain steroid hormones might be realized through the impact on MPO activity.

Comparison of the effects of alpha-tocopherol, ubiquinone-10 and probucol at therapeutic doses on atherosclerosis in WHHL rabbits.

Oxidative modification of lipoproteins may trigger and maintain atherogenesis. We compared the effects of different antioxidants (alpha-tocopherol, probucol, ubiquinone-10) at doses similar to those used in humans in Watanabe Heritable Hyperlipidemic (WHHL) rabbits for 12 months. Aortic lesions were analyzed for their extent and cellular composition of lesions, mean thickness of fibrous caps and density of smooth muscle cells therein, content of antioxidants, non-oxidized and oxidized lipids. Compared to controls, probucol significantly lowered the extent and macrophage content of lesions and increased the existence and smooth muscle cell density of fibrous caps. alpha-Tocopherol supplementation increased the aortic content of vitamin E, but had no decreasing effect on either the accumulation of macrophage-specific antigen in the aorta or lesion size. Nevertheless, both probucol and alpha-tocopherol significantly decreased in vitro LDL oxidizability, measured under typically strong oxidative conditions. Ubiquinone-10 supplement increased lesion size and the fraction of lesions containing fibrous caps; however, LDL oxidizability remained unaffected by ubiquinone-10 treatment. None of the antioxidants tested lowered oxidized lipids within aortic tissue; however, long-term treatment with probucol provided the most effective anti-atherosclerotic effect, while alpha-tocopherol may be pro-atherogenic and ubiquinone-10 exerts ambivalent effects. Our data suggest that (i) widely used oxidation measures, such as ex-vivo LDL oxidizability, do not reflect the degree of atherosclerosis; and (ii) long-term beneficial effects of relatively low doses of antioxidants may be outweighed by high levels of plasma cholesterol in WHHL rabbits.

Modulation of the beta-adrenergic receptor system of vascular smooth muscle cells in vitro and in vivo by chronically elevated endothelin-1 levels.

Endothelin-1 (ET-1) levels are chronically elevated in several cardiovascular diseases and correlate with an increased mortality. However, in contrast to acute biological activities such as vasoconstriction, little is known about long-term effects of ET-1. In this study we determined the effects of ET-1 on the beta(2)-adrenergic receptor (AR) system. Incubation of smooth muscle cells with ET-1 for 72 hr led to increased beta(2)AR density as determined by radioligand binding. Experiments with inhibitors of protein and RNA synthesis as well as RT-PCR revealed that beta(2)AR upregulation required de novo synthesis. In addition, protein kinase C but neither NO nor prostaglandin metabolism were involved in this effect. The enhanced expression of beta(2)AR was associated with an increased expression of its stimulatory G-protein and the receptor's ability to stimulate adenylyl cyclase. To study chronic effects of ET-1 in vivo, rats were infused with ET-1 for 3 weeks. Similarly as in cultured cells, prolonged ET-1 exposure led to increased betaAR expression in vivo. As a consequence, beta(2)AR-induced vasodilatation was increased in aortic rings from ET-1-treated animals. Our results therefore suggest that chronically elevated ET-1 levels in vitro and in vivo induce counterregulatory mechanisms by increasing betaARs that attenuate the vasoconstrictive effects of ET-1.

Thin-layer chromatography and multivariate data analysis of willow bark extracts.

In most cases the pharmacological activity of plant extracts is not assigned to single components and often not all active ingredients are known. Approaches other than those considering single compounds only to analyze plant material have proven helpful for a better characterization of extracts in their entirety. In this study extracts of willow bark are analyzed by high-performance thin-layer chromatography (HPTLC) and two different pharmacological tests [the 2,2'-azobis (2-amidinopropane) dihydrochloride reaction and the xanthine/xanthine oxidase reaction] with the help of multivariate data analysis. Described are two models using the results of the chromatographic study of 22 various extracts of willow bark and their pharmacological properties. The chromatographic data are obtained by a special TLC scanner that enables measurement of HPTLC tracks simultaneously in the range of lambda = 200-400 nm. Additionally, the developed models are used to predict the activity of another three extracts of willow bark demonstrating the quality of the model.

Effect of potassium channel opener pinacidil on the contractions elicited electrically or by noradrenaline in the human radial artery.

In order to discover an agent that can prevent spasm of the human radial artery, the aim of our study was to evaluate the effect of the K(+) channel opener, pinacidil, on contractions in the radial artery. Contractions of the radial artery were evoked by exogenously applied noradrenaline or by electrical field stimulation (EFS, 20Hz, neurogenic). Pinacidil induced concentration-dependent inhibition of both EFS- and noradrenaline-evoked contractions of the radial artery. Glibenclamide, a selective blocker of ATP-sensitive K(+) channels (Kir6.x containing subunit) antagonized in the same manner the pinacidil-induced inhibition of neurogenic contractions and contractions evoked by exogenous noradrenaline. The inhibition of pinacidil relaxation by tetraethylammonium (TEA), a blocker of Ca-sensitive K(+) (K(Ca)) channels, was more pronounced in EFS-contracted preparations. A blocker of voltage-sensitive K(+) (K(V)) channels, 4-aminopyridine (4-AP), inhibited pinacidil relaxation only in EFS-contracted preparations. In order to test the presence of different K(+) channels, immunohistochemistry of K(+) channels expression in the radial artery was performed. The vascular wall of the human radial artery showed variable positivity with the following applied antibodies: Kv1.2, Kv1.3, Kir6.1, and K(Ca)1.1. The antibodies against Kv1.6, Kv2.1, and Kir6.2 channel subunits were completely negative. These results suggest that the inhibitory effect of pinacidil on contractions of the human radial artery might be postsynaptic and associated with opening of smooth muscle Kir6.1-containing K(ATP) channels. TEA- and 4-AP-sensitive K(+) channels may also contribute to pinacidil effect in the human radial artery.

Solubilization of resveratrol in micellar solutions of different bile acids.

Bile acids are a special group of biological surfactants which can express different physiological and pharmacological effects. Micellar solutions of bile acids can solubilizate poorly soluble organic substances and improve their resorbtion. Above their critical micellar concentration (CMC) values, bile acids can cause interruption of membrane's integrity. Resveratrol (trans-3,5,4'-trihydroxystilbene) is a stilbene phytoalexine and studies reported that it can prevent or reduce diseases such as cancer and coronary heart disease. In this study, we examined affinity of different bile acids (CA, 12-MDCA, 12-MCA, 7-MCA, 7,12-DCA, 3,7,12-TCA) micellar solutions for resveratrol solubilization. CMC values for bile acids were determined by conductivity measurements. Concentration of micellar solutions were 0.25, 0.5, 0.75, 1.0, 1.25, 1.5, 1.75, 2.0 CMC value, for each acid respectively. At the same time, we investigated membranolytical potential of each acid. Solubilizated resveratrol was quantified using HPLC system with UV detection. Membranolytical potential was determined from citrate rabbit blood. Structures of mixed micelles of each bile acid and resveratrol were explained, and multiple linear regression equations for solubilization of resveratrol on different concentrations of bile acids were obtained. Micellar solution of 3,7,12-TCA had the biggest affinity for resveratrol solubilization and then, in decreasing order 7-MCA>7, 12-DCA>12-MCA>12-MDCA>CA. Also, 3,7,12-TCA had the lowest membranolytical potential.

A role of ion channels in the endothelium-independent relaxation of rat mesenteric artery induced by resveratrol.

Recently it has been suggested that resveratrol relaxes different isolated arteries. The present study addressed the question whether different ion channels are involved in the endothelium-independent mechanism of vasodilatation induced by resveratrol. For that purpose, we tested the action of resveratrol on the rat mesenteric artery without endothelium. Resveratrol induced concentration-dependent relaxation of rat mesenteric artery. Among the K(+)-channel blockers, 4-amynopiridine (4-AP) moderately antagonized the resveratrol-induced relaxation, while glibenclamide, tetraethylammonium chloride, charybdotoxin, margatoxin, and barium chloride did not inhibit resveratrol-induced vasorelaxation. In rings, precontracted with 100 mM K(+), the relaxant responses to resveratrol were highly significantly shifted to the right compared to those obtained in rings precontracted with phenylephrine, but resveratrol-induced maximal relaxation was only slightly affected. In order to minimize the influence of K(+) channels and voltage-gated Ca(2+) channels (VGCCs) in vascular smooth muscle, the third contraction was made by 100 mM K(+) in the presence of nifedipine. The relaxant response to resveratrol was abolished. Thus, the mechanism of vasorelaxation induced by resveratrol probably involves activation of 4-AP-sensitive K(+) channels. Its ability to completely relax the mesenteric artery precontracted with K(+)-rich solution suggests that K(+) channel-independent mechanism(s) are involved in its vasorelaxant effect. It seems that interaction with VGCCs plays a part in this K(+) channel-independent effect of resveratrol.

Potassium channel opener pinacidil induces relaxation of the isolated human radial artery.

Taking into consideration that the search for drugs capable of modifying blood flow through human radial artery (RA) is warranted, the present study was designed to examine the vasodilatatory effects of the potassium channel opener, pinacidil on the RA and to define the contribution of different K+ -channel subtypes in the endothelium-independent pinacidil action on this blood vessel. Pinacidil relaxed the RA rings with endothelium and without endothelium with comparable potency. N-nitro-L-arginine methyl ester (L-NAME) and methylene blue did not affect the pinacidil-induced vasorelaxation in rings with endothelium. In the rings without endothelium, the K+ -channel blockers glibenclamide and tetraethylammonium (TEA) moderately antagonized the pinacidil-induced relaxation, while charybdotoxin and 4-aminopiridine did not. In endothelium-denuded rings, precontracted with 100 mM K+, the relaxant responses to pinacidil were highly significantly shifted to the right compared to those obtained in RA precontracted with phenylephrine, but pinacidil-induced maximal relaxation was not affected. Addition of nifedipine did not but addition of nifedipine and nickel (Na+ -Ca2+ exchanger inhibitor) did cause a statistically significant rightward shift of the pinacidil concentration-relaxation curve, although the effect 0.1 mM pinacidil was preserved. Thus, pinacidil induces relaxation of the human RA in endothelium-independent manner, and glibenclamide- and TEA-sensitive vascular smooth muscle K+ channels are probably involved. Its ability to completely relax the RA precontracted with K+ -rich solution suggests that pinacidil has additional K+ channel-independent mechanism(s) of action. It seems that stimulation of the forward mode of the Na+ -Ca2+ exchanger plays a part in this K+ channel-independent effect of pinacidil.

Wavelet analysis of skin perfusion in healthy volunteers.

OBJECTIVE: Rhythmical changes in microvascular perfusion of the skin depend on various influences, which appear continuously but not in a predictable manner. For identifying and quantifying different physiological influences the authors used wavelet transformation, analyzing continuously and simultaneously measured data. METHODS: A total of 34 healthy volunteers were included in the study. At the dorsum of the left hand, skin perfusion was measured by laser Doppler fluxmetry (LDF) and skin temperature was measured. Simultaneously, the electrocardiogram and the respiration were recorded. The recorded time series were analyzed with wavelet transformation and scale correlation (S-correlation). RESULTS: Semilinear analysis with wavelet transformation allowed a visualization of temporal changes in LDF frequency and amplitude in a color-coded quasi three-dimensional diagram. The authors found that tissue perfusion over an observation period of 327.68 s is governed by 6 closely connected, overlying waves with different degrees of freedom. The major determinants are low frequencies in LDF, which correlates with changes in skin temperature, responsible for 68.5% of the influence. Surprisingly, though indispensable for blood flow, respiration and heartbeat contributed to less then 2.5% of the rhythmic changes. CONCLUSIONS: When wavelet transformation is used in analyzing LDF time series, the different rhythms of cutaneous blood flow are made visible and quantifiable and can be assigned to different physiological origins. The application of this novel analysis method allows identifying mechanisms regulating skin perfusion, which will greatly facilitate the diagnosis of a variety of important vascular diseases, such as chronic venous insufficiency, diabetes, or neurotrophic disorders.

Analysis of vasoreactivity of isolated human radial artery.

Radial artery (RA) is increasingly used as graft for coronary artery bypass grafting due to its good long-term patency. However, the mechanism of peri- and post-operative spasm is still unclear. Because of that, the aim of our study is to analyze the contractility of RA and to determine whether the presence of functional endothelium alters its contractile properties. Contractions of isolated RA rings were provoked by exogenously applied vasoconstrictors or by electrical field stimulation (EFS, 20 Hz). The order of vasoconstrictors potency based on their EC50 values was as follows: angiotensin II > phenylephrine > 5-hydroxytriptamine. Presence of endothelium increased both EC50 and maximal contraction to phenylephrine and angiotensin II, but inhibited reactivity of RA to 5-hydroxytriptamine. Spontaneous rhythmic contractions (SRC, <4 mHz) and EFS-induced contractions of RA are endothelium-independent and weaker than contractions induced by exogenously applied vasoconstrictors. Our study concludes that RA shows marked sensitivity and reactivity to angiotensin II, phenylephrine, and 5-hydroxytriptamine. Further investigations are necessary to answer why angiotensin II and phenylepehrine induce stronger contractions in the presence of endothelium. In addition, SRC as well as contractions of neurogenic origin may take part in developing vascular spasm of RA.