In vivo 31P nuclear magnetic resonance evidence of the salvage effect of ascorbate on the postischemic reperfused rat skeletal muscle

Effects of light-emitting diode (LED) therapy on skeletal muscle ischemia reperfusion in rats

Low-level laser therapy has been shown to decrease ischemia-reperfusion injuries in the skeletal muscle by induction of synthesis of antioxidants and other cytoprotective proteins. Recently, the light-emitting diode (LED) has been used instead of laser for the treatment of various diseases because of its low operational cost compared to the use of a laser. The objective of this work was to analyze the effects of LED therapy at 904 nm on skeletal muscle ischemia-reperfusion injury in rats. Thirty healthy male Wistar rats were allocated into three groups of ten rats each as follows: normal (N), ischemia-reperfusion (IR), and ischemia-reperfusion + LED (IR + LED) therapy. Ischemia was induced by right femoral artery clipping for 2 h followed by 2 h of reperfusion. The IR + LED group received LED irradiation on the right gastrocnemius muscle (4 J/cm(2)) immediately and 1 h following blood supply occlusion for 10 min. At the end of trial, the animals were euthanized and the right gastrocnemius muscles were submitted to histological and histochemical analysis. The extent of muscle damage in the IR + LED group was significantly lower than that in the IR group (P < 0.05). In comparison with other groups, tissue malondialdehyde (MDA) levels in the IR group were significantly increased (P < 0.05). The muscle tissue glutathione (GSH), superoxide dismutases (SOD), and catalase (CAT) levels in the IR group were significantly lower than those in the subjects in other groups. From the histological and histochemical perspective, the LED therapy has alleviated the metabolic injuries in the skeletal muscle ischemia reperfusion in this experimental model.

Irradiation at 634 nm releases nitric oxide from human monocytes

Previous studies have shown that irradiation at 634 nm decreases the release of extracellular reactive oxygen species (ROS) without affecting viability in human monocytes. Here, we examined the effect of irradiation at 634 nm on the release of nitric oxide (NO), activation of inducible nitric oxide synthase (iNOS) and endothelial NOS (eNOS), and release of intracellular ROS. Chemiluminescence assays were used to measure NO release, intracellular ROS, and adenosine triphosphate levels (to assess cell viability). Levels of iNOS and eNOS mRNA were analyzed using PCR. Irradiation resulted in elevated levels of NO but had no effect on iNOS or eNOS. Irradiation also caused a decrease in levels of intracellular ROS and had no effect on cell viability. Our studies indicate that irradiation at 634 nm releases NO, possibly from a preformed store, and reduces the production of intracellular ROS without affecting cell viability. Irradiation at 634 nm may have a wide range of clinical applications, including a reduction in oxidative stress-mediated injury in the vasculature.

Vitamin C homeostasis in skeletal muscle cells

In skeletal muscle, vitamin C not only enhances carnitine biosynthesis but also protects cells against ROS generation induced by physical exercise. The ability to take up both ascorbic and dehydroascorbic acid from the extracellular environment, together with the ability to recycle the intracellular vitamin, maintains high cellular stores of ascorbate. In this study, we examined vitamin C transport and recycling, by using the mouse C2C12 and rat L6C5 muscle cell lines, which exhibit different sensitivity to oxidative stress and GSH metabolism. We found that: (1) both cell lines express SVCT2, whereas SVCT1 is expressed at very low levels only in proliferating L6C5 cells; furthermore L6C5 myoblasts are more efficient in ascorbic acid transport than C2C12 myoblasts; (2) C2C12 cells are more efficient in dehydroascorbic acid transport and ascorbyl free radical/dehydroascorbic acid reduction; (3) differentiation is paralleled by decreased ascorbic acid and dehydroascorbic acid transport and reduction and increased ascorbyl free radical reduction; (4) differentiated cells are more responsive to oxidative stress induced by glutathione depletion; indeed, myotubes showed increased SVCT2 expression and thioredoxin reductase-mediated dehydroascorbic acid reduction. From our data, SVCT2 and NADPH-thioredoxin-dependent DHA reduction appears to belong to an inducible system activated in response to oxidative stress.

Enhanced post-ischaemic recovery in rabbit kidney after pretreatment with an indeno-indole compound and ascorbate monitored in vivo by 31P magnetic resonance spectroscopy

OBJECTIVE

To investigate whether combined pretreatment with lipid- and water-soluble antioxidants gave better restoration of energy phosphates after ischaemia-reperfusion of rabbit kidneys than single pretreatment with a lipid-soluble antioxidant.

MATERIAL AND METHODS

Thirteen New Zealand white rabbits were used for the study. Changes in energy phosphates were measured in vivo using volume-selective 31P magnetic resonance spectroscopy. The indeno-indole compound H290/51 was chosen as a lipid-soluble antioxidant and ascorbate as a water-soluble antioxidant.

RESULTS

The combined pretreatment led to significantly better restoration of the beta-adenosine triphosphate:inorganic phosphate ratio after 60 min of ischaemia and 120 min of reperfusion compared with the single pretreatment. Analyses of blood pressure and blood gas changes showed that the beneficial effect of combined pretreatment was not caused by a better general condition of the animals in that group but by a direct effect on the kidneys.

CONCLUSIONS

Combined pretreatment with lipid- and water-soluble antioxidants leads to better restoration of energy phosphates in rabbit kidneys subjected to ischaemia-reperfusion compared with single pretreatment with a lipid-soluble antioxidant.

Effect of hypothermia on the ischemic and reperfused rat skeletal muscle, monitored by in vivo (31)P-magnetic resonance spectroscopy

The aim of this study was to compare the ischemic and postischemic energetic changes of rat skeletal muscle in response to hypothermia or room temperature, monitored noninvasively and continuously by in vivo (31)P-magnetic resonance spectroscopy ((31)P-MRS). A model of pedicled rat rectus femoris muscle was developed and analyzed by in vivo (31)P-MRS at a magnetic field strength of 2.35 T. Measurements were performed at three time points: before ischemia, after 4 hours of ischemia, and after 1 hour of reperfusion. Three groups were studied: (1) sham-operated rats (n = 6); (2) rats subjected to room temperature (24-26 degrees C, n = 6); and (3) rats subjected to hypothermia (9-12 degrees C, n = 6). Blood perfusion was measured by laser Doppler flowmetry (LDF). In the hypothermic group, phosphocreatine (PCr) recovered to 75% and adenosine triphosphate (ATP) to 86%; in the room temperature group, the recovery was 53% and 51%, respectively (P < 0.05). Skeletal muscle subjected to hypothermia (9-12 degrees C) was found to recover to a higher postischemic energetic level compared with skeletal muscle subjected to room temperature. Hypothermia appears to be a simple and effective method with which to reduce the damage related to ischemia and reperfusion.

Comparison of histopathologic effects of carnitine and ascorbic acid on reperfusion injury

OBJECTIVE

Reperfusion injury can be seen after acute arterial occlusion, acute myocardial infarctus and during open heart surgery and vascular surgery. Protective effects of ascorbic acid and carnitine on reperfusion damage were tested and compared using histopathologic examination on ischemia model in the rabbit hind limb.

METHODS

Four groups (each containing ten animals) were used. In group I (G1), only anesthesia was administered and a biopsy was taken from the soleus muscle after 6 h. In group II (G2), group III (G3), and group IV (G4), after induction of anesthesia, arterial blood circulation of right posterior extremity was blocked by a tourniquet proximally. After four hours of ischemia, just before releasing of tourniquet, physiologic saline solution, sodium ascorbate (Redoxan) and L-carnitine (Carnitine) were administered intravenously to G2, G3 and G4, respectively. Following 2 h of reperfusion, biopsies were taken from soleus muscles. All of the biopsy slides were observed under the light microscope from the aspect of six different histopathologic criteria (loss of striation, nuclear centralisation, formation of ring and/or splitting, changing on diameters of muscle fibers, necrosis and minimal fibrosis) of ischemic muscle.

RESULTS

Ischemic change criteria were seen less frequency in both vitamin C and carnitine groups compared to the control and placebo groups. However, this protective effect was statistically significant only for the aspect of segmental necrosis, centralization of nuclei and diameter change parameters in G3 and in G4. When G3 and G4 were compared, the differences on protective effects were significant only from the aspect of fibrosis (P<0.001) and changing on diameter of the fibers (P<0.001).

CONCLUSIONS

Both sodium ascorbate and carnitine are effective on reducing the reperfusion injury in skeletal muscle. But when we compared these two agents to each other, we found that carnitine seems a little more protective on our experimental model.

Harmful singlet oxygen can be helpful

Highly reactive harmful singlet oxygen O2(1delta(g)) can be helpful while relaxing to its triplet ground state O2(3sigma(g)-). The energy emitted during this relaxation from the excited energy state is discernable at 634 nm. We report here on the effect of this energy as photon illumination and as energy transfer in air on the production of reactive oxygen species (ROS) by human monocytes, measured as isoluminol-enhanced chemiluminescence. We demonstrate up to 60% decrease in the secretion of ROS after 2-min illumination of the monocytes stimulated with phorbol myristate acetate (PMA). The results provide in vitro documentation of the utility of singlet oxygen energy in modifying cellular behaviour.

In vivo microdialysis of 2-deoxyglucose 6-phosphate into brain: a novel method for the measurement of interstitial pH using 31P-NMR

A unique method for simultaneously measuring interstitial (pHe) as well as intracellular (pHi) pH in the brains of lightly anesthetized rats is described. A 4-mm microdialysis probe was inserted acutely into the right frontal lobe in the center of the area sampled by a surface coil tuned for the collection of 31P-NMR spectra. 2-Deoxyglucose 6-phosphate (2-DG-6-P) was microdialyzed into the rat until a single NMR peak was detected in the phosphomonoester region of the 31P spectrum. pHe and pHi values were calculated from the chemical shift of 2-DG-6-P and inorganic phosphate, respectively, relative to the phosphocreatine peak. The average in vivo pHe was 7.24+/-0.01, whereas the average pHi was 7.05+/-0.01 (n = 7). The average pHe value and the average CSF bicarbonate value (23.5+/-0.1 mEq/L) were used to calculate an interstitial Pco2 of 55 mm Hg. Rats were then subjected to a 15-min period of either hypercapnia, by addition of CO2 (2.5, 5, or 10%) to the ventilator gases, or hypocapnia (PCO2 < 30 mm Hg), by increasing the ventilation rate and volume. pHe responded inversely to arterial Pco2 and was well described (r2 = 0.91) by the Henderson-Hasselbalch equation, assuming a pKa for the bicarbonate buffer system of 6.1 and a solubility coefficient for CO2 of 0.031. This confirms the view that the bicarbonate buffer system is dominant in the interstitial space. pHi responded inversely and linearly to arterial PCO2. The intracellular effect was muted as compared with pHe (slope = -0.0025, r2 = 0.60). pHe and pHi values were also monitored during the first 12 min of ischemia produced by cardiac arrest. pHe decreases more rapidly than pHi during the first 5 min of ischemia. After 12 min of ischemia, pHe and pHi values were not significantly different (6.44+/-0.02 and 6.44+/-0.03, respectively). The limitations, advantages, and future uses of the combined microdialysis/31P-NMR method for measurement of pHe and pHi are discussed.

In vivo 31P NMR OSIRIS of bioenergetic changes in rabbit kidneys during and after ischaemia: effect of pretreatment with an indeno-indole compound

Changes in energy phosphates of rabbit kidneys subjected to ischaemia-reperfusion have been measured in vivo with volume selective 31P NMR spectroscopy. The effects of pretreatment with a new lipid peroxidation inhibitor (indeno-indol derivate--code name H290/51) on the bioenergetic changes were analysed. The left kidney was moved to a subcutaneous pocket to facilitate exact positioning over the surface coil. A 1H NMR image was acquired and a 3.5-mL cube selected for 31P NMR spectra. 31P NMR spectra were recorded before occlusion of the left renal artery, during 1 h of ischaemia and 2 hours of reperfusion. Ischaemia induced drastic changes in the levels of inorganic phosphates and ATP as well as intracellular acidosis. A normalization was observed during reperfusion. Two hours after reperfusion significantly higher values for beta-ATP/Pi and intracellular pH were recorded in the animals pretreated with H290/51. The present technique allows quantitative analyses of changes in kidney bioenergetics in vivo during different experimental conditions. The importance of ischaemia-reperfusion induced lipid peroxidation for mitochondrial function is emphasized.

Phosphorus metabolites in different muscles of the rat leg by 31P image-selected in vivo spectroscopy

The difference in concentration of phosphorylated metabolites in muscles with different fiber composition was studied in vivo by localized 31P nuclear magnetic resonance spectroscopy in the rat hindlimb 120-160 microliters volumes were selected in regions containing the soleus and gastrocnemius muscles. Concentrations of phosphocreatine (PCr), adenosine triphosphate and inorganic phosphate (Pi) were determined and intracellular pH was calculated in the respective muscle groups. The highest level of PCr was found in the gastrocnemius muscle, containing 30.7 mmoles/dm3 tissue compared to 22.3 mmoles/dm3 in the soleus muscle. Pi was significantly lower in gastrocnemius (1.9 mmoles/dm3) than in soleus (3.2 mmoles/dm3). The ATP concentration was 6.7 and 6.4 mmoles/dm3 and pH was determined to 7.11 and 7.09 in the gastrocnemius and soleus muscle, respectively. Our NMR data show that it is possible to measure high-energy phosphates with precision in small localized volumes with the ISIS method using a Helmholtz coil. Earlier biochemical data are confirmed by these in vivo NMR results. Localized in vivo 31P NMR spectroscopy can contribute to the understanding of the underlying mechanisms of several metabolic events in different regions of the tissue. The method can be used for future studies of varying ischemia tolerance, varying degrees of adaptation to exercise with regard to oxidative capacity, and pH compartmentation in muscles with different fiber composition.

Ascorbate attenuates the systemic kainate-induced neurotoxicity in the rat hippocampus

The neuronal damage induced by systemic administration of kainic acid reproduces the cellular and regional pattern of damage produced by repeated seizures. The ability of kainic acid to induce lipid peroxidation, and the ability of free radical inhibitors to prevent ischaemically-induced cell death, has led us to examine the possible role of free radicals in kainate-induced injury. Ascorbic acid was able to reduce kainate-induced damage of the rat hippocampus, measured by means of the gliotic marker ligand [3H]PK11195. Ascorbate was significantly effective at doses of 30 mg kg-1 and above, with total protection against kainate at 50 mg kg-1. Histologically, ascorbate at 50 mg kg-1 was able to prevent kainate-induced neuronal loss in the hippocampal CA1 and CA3a cell layers. The antioxidant was also effective when administered simultaneously with, or 1 h before the kainate. Protection was also obtained by allopurinol, 175 mg kg-1 and by oxypurinol, 40 mg kg-1. Ascorbate did not modify synaptically evoked potentials or long-term potentiation in hippocampal slices, ruling out any blocking activity at glutamate receptors. It is concluded that the neuronal damage produced by systemically administered kainate involves the formation of free radicals.