L-arginine Acetate Research Articles

Hydrogen bonding interaction and topological insights of the electron localization/delocalization of l- arginine acetate

The vibrational spectral studies of the semi-organic material l- arginine acetate (LAA) are carried out with the help of density functional calculations to derive the equilibrium geometry as well as the vibrational wavenumbers and intensities of the spectral bands. The vibrational spectrum assignments are performed using normal coordinate analysis (NCA) in accordance with the scaled quantum mechanical force field approach (SQMFF). Vibrational spectra confirm the COO- modes split due to intra- and intermolecular association based on C–O….H, N–H….O, and O–H⋯O hydrogen bonding in the molecule, which lowers carboxylate wavenumbers. The natural bond orbital (NBO) analysis and DFT computations also confirm the occurrence of strong intra and intermolecular N–H⋯O and O–H⋯O ionic hydrogen bonding between charged species, providing the non-centrosymmetric structure in the LAA crystal.

Insulin-induced membrane permeability to glucose in human muscles at rest and following exercise.

Increased insulin action is an important component of the health benefits of exercise, but its regulation is complex and not fully elucidated. Previous studies of insulin-stimulated GLUT4 translocation to the skeletal muscle membrane found insufficient increases to explain the increases in glucose uptake. By determination of leg glucose uptake and interstitial muscle glucose concentration, insulin-induced muscle membrane permeability to glucose was calculated 4h after one-legged knee-extensor exercise during a submaximal euglycaemic-hyperinsulinaemic clamp. It was found that during submaximal insulin stimulation, muscle membrane permeability to glucose in humans increases twice as much in previously exercised vs. rested muscle and outstrips the supply of glucose, which then becomes limiting for glucose uptake. This methodology can now be employed to determine muscle membrane permeability to glucose in people with diabetes, who have reduced insulin action, and in principle can also be used to determine membrane permeability to other substrates or metabolites. Increased insulin action is an important component of the health benefits of exercise, but the regulation of insulin action in vivo is complex and not fully elucidated. Previously determined increases in skeletal muscle insulin-stimulated GLUT4 translocation are inconsistent and mostly cannot explain the increases in insulin action in humans. Here we used leg glucose uptake (LGU) and interstitial muscle glucose concentration to calculate insulin-induced muscle membrane permeability to glucose, a variable not previously possible to quantify in humans. Muscle membrane permeability to glucose, measured 4h after one-legged knee-extensor exercise, increased ∼17-fold during a submaximal euglycaemic-hyperinsulinaemic clamp in rested muscle (R) and ∼36-fold in exercised muscle (EX). Femoral arterial infusion of NG -monomethyl l-arginine acetate or ATP decreased and increased, respectively, leg blood flow (LBF) in both legs but did not affect membrane glucose permeability. Decreasing LBF reduced interstitial glucose concentrations to ∼2mM in the exercised but only to ∼3.5mM in non-exercised muscle and abrogated the augmented effect of insulin on LGU in the EX leg. Increasing LBF by ATP infusion increased LGU in both legs with uptake higher in the EX leg. We conclude that it is possible to measure functional muscle membrane permeability to glucose in humans and it increases twice as much in exercised vs. rested muscle during submaximal insulin stimulation. We also show that muscle perfusion is an important regulator of muscle glucose uptake when membrane permeability to glucose is high and we show that the capillary wall can be a significant barrier for glucose transport.

Physico-chemical, structural, optical and NLO studies on pure and La3+ doped l-arginine acetate crystals

Pure and La3+ doped single crystals of l-arginine acetate (LAA) have been grown well from through slow evaporation method in aqueous environment. The Crystalline nature can be confirmed by powder X-Ray Diffraction (XRD) Analysis. The function groups with possible stretching/bonding were identified through FTIR (Fourier Transform Infrared Spectroscopy) and Fourier Transform Raman Spectroscopy (FT-Raman) analysis. The good optical properties of La3+ doped LAA crystals were found through UV–Visible spectral analysis. Nonlinear optical (NLO) behavior through Kurtz’s method reveals that the dopant has increased the efficiency. Further, grown crystals has examined for thermal (TGA, DTA), mechanical (Vicker’s), dielectric (LCR) and photo conductive (picoammeter) properties enhanced with La3+ dopant and the results are interpreted and discussed.

PL - 026 Mismatch between skeletal muscle glucose delivery, interstitial concentration and membrane permeability may limit insulin sensitivity after exercise

Objective The relationship between skeletal muscle perfusion, interstitial glucose concentration and sarcolemmal permeability to glucose in exercise-induced increases in muscle insulin sensitivity is not well established. A single bout of exercise increases skeletal muscle insulin sensitivity through coordinated increases in insulin-stimulated microvascular perfusion and insulin signalling Reducing leg and muscle microvascular blood flow with local nitric oxide synthase (NOS) inhibition during a hyperinsulinaemic euglycaemic clamp reduces leg glucose uptake in a previously exercised, but not in a contralateral non-exercised leg, without affecting insulin signalling in either leg (Sjoberg et al. 2017). Therefore, it is possible that the reduction in muscle perfusion decreases muscle interstitial glucose concentration to a point that limits skeletal muscle insulin-stimulated glucose uptake following exercise. We examined this using microdialysis of vastus lateralis muscle.
 Methods Ten healthy males (Age: 27±1 yr., Weight: 77.7±2.3 kg, BMI 23.9±0.5, VO2 peak: 50.7±1.5 ml·kg-1·min-1) performed 60 min of 1-legged knee extensor exercise at 80% of 1-legged peak work load with three 5 min intervals at 100% 1-legged peak work load. Participants then rested for 4 hours and catheters were inserted into the femoral artery and vein of both legs for subsequent measurement of leg glucose uptake and for femoral artery infusion of the NOS inhibitor NG-monomethyl L-arginine acetate (L-NMMA) and the vasodilator ATP. Catheters were also placed in antecubital veins for infusion of insulin and glucose. Three microdialysis catheters, with a semi-permeable membrane the length of 30 mm and a molecular cut-off at 20,000 dalton, were inserted into the vastus lateral muscle of both legs. Glucose and D-[6-3H(N)]glucose were added to the perfusate. Four hours after discontinuing the exercise a 225 minute euglycaemic hyperinsulinaemic clamp was initiated (insulin infusion 1.4 mU-1kg-1min). Ninety min into the clamp L-NMMA was infused at a constant rate (0.4 mg·kg-1 leg mass·min-1) into both femoral arteries for 45 min. The insulin infusion was maintained for another 90 min and during the last 45 min ATP (0.3 μmol∙ml-1) was infused locally into both femoral arteries at a rate of 200-350 μl∙min-1 to obtain a leg blood flow that was double the blood flow during insulin only infusion. A second control protocol was undertaken that was identical in regards to exercise and recovery but no insulin, L-NMMA or ATP was infused.
 Results During the clamp leg glucose uptake and leg blood flow were higher (P<0.05) in the previously exercised than the control leg whereas the interstitial glucose concentration decreased to lower (P<0.05) values in the exercised (~3.1mM) than the control (~4.8mM) leg. Estimated sarcolemmal glucose permeability was twice as high (P<0.05) in the exercised compared with the rested leg. The NOS inhibitor L-NMMA decreased LBF in both legs and interstitial glucose concentration dropped to ~2.3 mM in the exercised but only to ~3.7 mM in non-exercised muscle. This abrogated the augmented effect of insulin on LGU in the exercised leg while apparent sarcolemmal permeability to glucose remained unchanged with L-NMMA in both legs. Doubling leg blood flow by local infusion of ATP increased leg glucose uptake in both legs without any major change in interstitial glucose concentration or sarcolemmal permeability to glucose.
 Conclusions These findings suggest that during flow restriction due to L-NMMA, the interstitial glucose concentration becomes limiting for leg glucose uptake in exercised but not in non-exercised muscle. Therefore, the vasodilatory effect of insulin is an important component of the increased insulin sensitivity to stimulate glucose uptake following exercise by limiting the drop in the interstitial glucose concentration that occurs due to the increased sarcolemmal permeability to glucose.
 Reference
 Sjoberg, K. A., C. Frosig, R. Kjobsted, L. Sylow, M. Kleinert, A. C. Betik, C. S. Shaw, B. Kiens, J. F. P. Wojtaszewski, S. Rattigan, E. A. Richter, and G. K. McConell. Exercise Increases Human Skeletal Muscle Insulin Sensitivity via Coordinated Increases in Microvascular Perfusion and Molecular Signaling. Diabetes 66: 1501-10, 2017.

Комплекс L-аргинина с сульфатом ацетата целлюлозы и его влияние на развитие эндотелиальной дисфункции у крыс

Установлен состав комплекса L-аргинина с сульфатом ацетата целлюлозы в форме натриевой соли и охарактеризовано его строение с помощью компьютерного моделирования и спектральных методов. Показана применимость уравнения Ленгмюра для описания изотерм адсорбции комплекса на активированных углях различного происхождения. Определено, что высвобождение аминокислоты из иммобилизованного комплекса происходит преимущественно в щелочной среде. В дозировке 70 – 200 мг/кг по L-аргинину комплекс проявляет выраженную кардиопротективную активность и обладает антигипертензивным и эндотелиопротективным действием.

Investigation on effect of LiCl doping on optical properties of L-arginine acetate single crystal

In the present study, L-arginine acetate (LAA) crystals with various level of LiCl doping were grown by low temperature solution growth method at a constant temperature. The effect of lithium chloride (LC) doping on the linear optical and second harmonic generation (SHG) properties of LAA crystal has been studied. The X-ray diffraction study has been performed to confirm the crystal structure of grown crystals. The enhancement in the optical transparency in doped crystals has been attested by ultraviolet-visible-infrared spectroscopic study. The photoluminescence studies have also been presented. The Kurtz - Perry test confirmed the increase in SHG efficiency of LAA crystal after addition of LC.

Growth and characterization of alkali metal doped l-arginine acetate single crystals for higher harmonic generation

The single crystals of l-arginine Acetate (LAA) and Na doped LAA were grown by slow evaporation method and characterized by chemically, structurally, thermally, mechanically and optically. The grown crystals belongs to monoclinic system was confirmed by single crystal X-ray diffraction analysis. The optical absorption spectrum gives the details about cut off wavelength and optical band gap of the grown crystal. The grown crystals were found to be thermally stable up to 202–208 °C. The hardness measurement indicates that the grown crystal of LAA comes under the soft material category and Na doped LAA comes under the hard material category. The nonlinear refractive index n2, non-linear absorption co-efficient (β), and non linear susceptibility χ(3) were calculated by Z-scan technique. The results indicate that the grown crystal of pure and doped LAA exhibits reverse saturation absorption and self defocusing performance.

Formation and properties of L-arginine acetate single crystals doped with hydrochloric acid

L-Arginine acetate (LAA) single crystals belonging to the amino acid group are reported to have promising NLO properties. In the present study, to improve further the characteristics of LAA crystals, HCl acid was incorporated into the crystal matrix as a dopant. Single crystals of pure and HCl doped LAA (a total of five) were grown successfully by using the slow evaporation technique. The grown crystals were confirmed chemically and structurally by performing X-ray diffraction (single crystal and powder), CHNS elemental, energy dispersive X-ray spectral and Fourier transform infrared spectral analyses. The crystals are found to be thermally stable up to 204 o C.The UV-Vis spectral analysis shows that these crystals have wide transparency range in the entire visible region. Second harmonic generation (SHG) measurement shows the NLO property. Microhardness measurement indicates that the grown crystals come under soft material category. Dielectric measurements were carried out at various temperatures ranging from 40- 140 ⁰C and with various frequencies such as 1 , 10 and 100 kHz by the parallel plate capacitor method. The AC activation energies were also determined. The temperature and frequency dependences of dielectric parameters observed indicate a normal dielectric behavior for all the five crystals grown in the present study.

Rapid crystallization of l-arginine acetate on engineered surfaces using metal-assisted and microwave-accelerated evaporative crystallization

We report the application of our newly described crystallization technique, which employs silver island films (SIFs) and microwave heating, to rapid crystallization of L-arginine acetate (LAA). Using our technique, LAA crystals (~ 1.2 mm in length) were grown from a 20 μl solution in 1 min on surface functionalized SIFs. In control experiments (glass slides and at room temperature) the growth of LAA crystals (0.1-0.3 mm) took ~ 55 min.

Synthesis, growth and optical properties of semi organic non linear optical single crystal: l-Arginine acetate

In the recent past, nonlinear optical materials are getting attention in the field fibre optic communication and optical signal processing. In the present study, the title compound was successfully synthesized by conventional chemical reaction and then the single crystal was grown by slow evaporation solution growth technique. l-Arginine acetate (LAA) is semi organic non linear optical single crystal and crystallizes in noncentrosymmetric space group. The grown good quality single crystals have been analyzed by different characterization analyses such as powder X-ray diffraction, high resolution X-ray diffraction (HRXRD), Raman spectroscopy, photoluminescence, SEM, micro-hardness, thermal and birefringence analyses.

Growth and characterization of pure and doped NLO L-arginine acetate single crystals

Single crystals of pure, Cu2+ and Mg2+ doped L-arginine acetate (LAA) were grown successfully by slow evaporation technique. In order to improve the device characteristics of LAA crystals, metal dopants of Cu2+ and Mg2+ were incorporated into the parent crystals. The grown pure and doped crystals were confirmed by X-ray powder diffraction studies. The pure and doped crystals were characterized by Fourier transform Raman (FT-Raman) and thermal studies. Absorptions of these grown crystals were analysed using UV-Vis-NIR studies, and it was found that these crystals possess minimum absorption in the entire visible region. Nonlinear optical studies of pure and doped crystals were carried out and it reveals that the dopants have increased the efficiency of LAA crystals.

Aging Is Associated With Reduced Prostacyclin-Mediated Dilation in the Human Forearm

Aging is associated with reduced endothelial function. There is indirect evidence for reduced prostacyclin (PGI(2))-mediated vasodilation with aging, but it is unknown whether this is because of reduced dilation to PGI(2) or altered production. In addition, the contribution of endothelial NO to PGI(2)-mediated dilation is unknown. Using plethysmography to determine forearm blood flow, we studied the effect of PGI(2) in 10 older (61 to 73 years) and 10 younger (19 to 45 years) subjects using 3 escalating intra-arterial doses of PGI(2) (epoprostenol). PGI(2) was also administered after NO synthase inhibition with N(G)-monomethyl-l-arginine acetate. The percent of change in forearm vascular conductance (mean+/-SEM) from baseline after PGI(2) was significantly lower (P=0.002) in the aging individuals (52+/-11%, 164+/-23%, and 221+/-27% versus 115+/-20%, 249+/-19%, and 370+/-35%). In addition, the group-by-dose interaction was also significant (P=0.018). After NO synthase inhibition, the dose-response curve to PGI(2) was blunted in the young subjects but unchanged in the older subjects; the difference between the groups was no longer significant. Our data suggest that the reduced dilator effects of PGI(2) in older individuals are attributable to a reduction in the contribution of endothelial-derived NO versus alterations in the direct effects of PGI(2) on vascular smooth muscle.

Bradykinin Protects Against Oxidative Stress–Induced Endothelial Cell Senescence

Premature aging (senescence) of endothelial cells might play an important role in the development and progression of hypertension and atherosclerosis. We hypothesized that bradykinin, a hormone that mediates vasoprotective effects of angiotensin-converting enzyme inhibitors, protects endothelial cells from oxidative stress-induced senescence. Bradykinin treatment (0.001 to 1 nmol/L) dose-dependently decreased senescence induced by 25 micromol/L of H(2)O(2) in cultured bovine aortic endothelial cells, as witnessed by a complete inhibition of increased senescent cell numbers and a 34% reduction of the levels of the senescence-associated cell cycle protein p21. Because H(2)O(2) induces senescence through superoxide-induced DNA damage, single-cell DNA damage was measured by comet assay. Bradykinin reduced DNA damage to control levels. The protective effect of bradykinin also resulted in a significant increase in the migration of H(2)O(2)-treated bovine aorta endothelial cells in an in vitro endothelial injury model, or "scratch" assay. The protective effect of bradykinin was abolished by the bradykinin B2 receptor antagonist HOE-140 and the NO production inhibitor N(omega)-methyl-L-arginine acetate salt. Therefore, we conclude that bradykinin protects endothelial cells from superoxide-induced senescence through bradykinin B2 receptor- and NO-mediated inhibition of DNA damage.

X-ray studies on crystalline complexes involving amino acids and peptides. X. Head-to-tail sequences in the crystal structure of L-lysine acetate.

L-Lysine acetate crystallises in the monoclinic space group P21 with a = 5.411 (1), b = 7.562(1), c = 12.635(2) A and beta = 91.7(1) degrees. The crystal structure was solved by direct methods and refined to an R value of 0.049 using the full matrix least squares method. The conformation and the aggregation of lysine molecules in the structure are similar to those found in the crystal structure of L-lysine L-aspartate. A conspicuous similarity between the crystal structures of L-arginine acetate and L-lysine acetate is that in both cases the strongly basic side chain, although having the largest pK value, interacts with the weakly acidic acetate group leaving the alpha-amino and the alpha-carboxylate groups to take part in head-to-tail sequences. These structures thus indicate that electrostatic effects are strongly modulated by other factors so as to give rise to head-to-tail sequences which have earlier been shown to be an almost universal feature of amino acid aggregation in the solid state.

L - arginine acetate single crystals for NLO applications

Single crystals of pure and Lanthanum doped L- arginine acetate (LAA) were grown successfully by slow evaporation technique. The grown crystals were confirmed by X-ray powder diffraction studies. The pure and doped crystals were characterized by Fourier Transform Infrared (FT-IR) and UV-Vis-NIR studies. It was found that the optical properties were enhanced by the incorporation of the dopant. Nonlinear optical studies reveal that the dopant has increased the efficiency of the LAA crystal.

Growth aspects and characteristic properties of pure and Li-doped l-arginine acetate (LAA) single crystals: A promising nonlinear optical material

Single crystals of pure and lithium (Li)-doped l-arginine acetate (LAA) were grown by the slow evaporation technique. The effect of Li-doping on the growth, structural and optical properties of LAA crystal has been investigated. Powder X-ray diffraction studies confirm the crystal structure of the grown pure and Li-doped LAA single crystals. Various types of functional groups of the grown pure and Li-doped LAA single crystals were identified by the Fourier transform infrared (FTIR) spectroscopic analysis. The presence of Li in the grown crystal was confirmed by atomic absorption spectroscopic analysis. Electrical properties of the Li-doped LAA crystal were analyzed by AC impedance studies. The optical transmission study shows that the Li-doped LAA crystal has good optical transparency in the UV and visible regions.

Growth and dielectric properties of l-arginine acetate and l-arginine oxalate single crystals

Single crystals of l-arginine acetate (LAA) and l-arginine oxalate (LAO), potential nonlinear optical materials, have been grown from respective aqueous solutions by using the slow cooling method. X-ray diffraction measurements confirmed the material of the grown crystals. Dielectric measurements were carried out at various temperatures ranging from 40–140 °C and with various frequencies ranging from 100 Hz–1 MHz along a- and c-directions by using the parallel plate capacitor method. Results indicate an increase of AC electrical parameters with the increase of temperature. The low ε r values observed (around 4 at 40 °C) indicate that both LAA and LAO are promising low ε r value dielectric materials.

Mechanism whereby nitric oxide (NO) infused chronically intrauterine in ewes is antiluteolytic rather than being luteolytic

Nitric oxide (NO) has been reported to be luteolytic in vitro and in vivo in cows. However, an NO donor reversed PGF 2α-induced inhibition of rat luteal progesterone secretion in vitro and an NO donor or endothelin-1 stimulated bovine luteal tissue secretion of prostaglandins E (PGE; PGE 1, PGE 2) in vitro without affecting progesterone or PGF 2α secretion. In addition, chronic infusion of an NO donor into the interstitial tissue of the ovarian vascular pedicle adjacent the luteal-containing ovary prevented the decline in circulating progesterone, while a nitric oxide synthase (NOS) inhibitor did not affect luteolysis. The objective of this experiment was to determine whether an NO donor or NOS inhibitor infused chronically intrauterine adjacent to the luteal-containing ovary during the ovine estrous cycle was luteolytic or antiluteolytic. Ewes were treated either with vehicle ( N = 5), diethylenetriamine (DETA-control for DETANONOate; N = 5), ( Z)-1-[2-(2-aminoethyl)- N-(2-ammonioethyl)amino]diazen-1-ium-1,2-diolate (DETANONOate-long acting NO donor; N = 6), l-arginine ( N = 5), l-nitro-arginine methyl ester ( l-NAME-NOS inhibitor; N = 6), or NG-monomethyl- l-arginine acetate ( l-NMMA; NOS inhibitor; N = 5) every 6 h from 2400 h (0 h) on day 8 through 1800 h on day 18 of the estrous cycle. Jugular venous blood and inferior vena cava plasma via a saphenous vein cathether 5 cm anterior to the juncture of the ovarian vein and inferior vena cava were collected every 6 h for analysis for progesterone and PGF 2α and PGE, respectively, by RIA. Corpora lutea were collected at 1800 h on day 18 and weighed. Weights of corpora lutea were heavier ( P ≤ 0.05) in DETANONOate-treated ewes when compared to vehicle, DETA, l-arginine, l-NAME, or l-NMMA-treated ewes, l-arginine luteal weights were heavier than vehicle, DETA, l-arginine, l-NAME, or l-NMMA-treated ewes, and luteal weights of vehicle, DETA, l-NAME, or l-NMMA-treated ewes did not differ amongst each other ( P ≥ 0.05). Profiles of progesterone in jugular venous blood on days 8–18 differed ( P ≤ 0.05) in DETANONOate-treated ewes when compared to vehicle, DETA, l-arginine, l-NMMA or l-NAME-treated ewes, which did not differ ( P ≥ 0.05) amongst each other. The PGE:PGF 2α ratio profile in inferior vena cava plasma of DETANONOate-treated ewes was increased ( P ≤ 0.05) when compared to all other treatment groups. In a second experiment, conversion of [ 3H PGE 2] to [ 3H PGF 2α] by day 15 ovine caruncular endometrium in vitro was determined in vehicle, DETA, or DETANONOate-treatment groups. Conversion of [ 3H PGE 2] to [ 3H PGF 2α] was decreased ( P ≤ 0.05) only by DETANONOate. It is concluded that NO is not luteolytic during the ovine estrous cycle, but may instead be antiluteolytic and prevent luteolysis by altering the PGE:PGF 2α ratio secreted by the uterus.

Growth and characterization of pure and doped nonlinear optical l‐arginine acetate single crystals

AbstractSingle crystals of organic nonlinear optical material of pure, Cu2+ and Mg2+ doped L‐arginine acetate (LAA) were successfully grown by slow evaporation method at room temperature. The UV‐Vis‐NIR spectra of pure and doped LAA indicate that these crystals possess a wide optical transmission window from 240‐1600 nm. Non‐linear optical studies reveal that the SHG efficiency of LAA is nearly three times that of KDP. The dielectric response of the samples was studied in the frequency region 100 Hz to 2 MHz and the influence of Cu2+ and Mg2+ substitution on the dielectric behaviour had been investigated. Photoconductivity study proves that both pure and Cu2+ and Mg2+ doped LAA crystal exhibit positive photoconductivity. It is evident from the Vickers hardness study that the hardness of the crystal decreases with increasing load both for pure and doped samples. ESR studies confirmed the incorporation of Cu2+ into LAA and the value of g‐factor was found to be 2.1654. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

The role of nitric oxide in δ-aminolevulinic acid (ALA)-induced photosensitivity of cancerous cells

Application of δ-aminolevulinic acid (ALA) results in the endogenous accumulation of protoporphyrin IX and is a useful approach in the photodynamic therapy (PDT) of cancers. To investigate the role of nitric oxide (NO) in the specific accumulation of protoporphyrin and ALA-induced PDT of cancerous cells, we transfected inducible-nitric oxide synthase (NOS2) cDNA into human embryonic kidney (HEK) 293T cells and examined the ALA-induced photo-damage as well as the accumulation of porphyrin in the cells. When the NOS2-expressing HEK293T cells were treated with ALA and then exposed to visible light, they became more sensitive to the light with accumulating porphyrins, as compared with the ALA-treated control cells. An increase in the generation of NO in transfected cells led to the accumulation of protoporphyrin with a concomitant decrease of ferrochelatase, the final step enzyme of heme biosynthesis. When mouse macrophage-like RAW264.7 cells were cultured with lipopolysaccharide and interferon-γ, the expression of NOS2 was induced. The addition of ALA to these cells led to the accumulation of protoporphyrin and cell death upon exposure to light. The treatment of cells with an NOS inhibitor, N G-monomethyl- l-arginine acetate, resulted in the inhibition of protoporphyrin accumulation and cell death. The levels of mitochondrial ferrochelatase and rotenone-sensitive NADH dehydrogenase in the NOS2-induced cells decreased. These results indicated that the generation of NO augments the ALA-induced accumulation of protoporphyrin IX and subsequent photo-damage in cancerous cells by decreasing the levels of mitochondrial iron-containing enzymes. Based on the fact that the production of NO in cancerous cells is elevated, NO in the cells is responsible for susceptibility with ALA-induced PDT.