Determination using impedance cardiograph of the chronic effects of different doses of radiotherapy on the cardiovascular system of rats.

AIM: Cardiac damage caused by radiation in the long term varies according to the radiation dose received by the heart. In this study, it was aimed to evaluate the damage caused by different radiation doses in the heart, together with hemodynamic parameters, immunhistochemistry, and histopathological analyzes for long term. METHOD AND MATERIALS: The animals were divided into four groups: The rats in control group (Group 1) were not irradiated; the rats in group 2 were irradiated with 5 Gy; the rats in group 3 were irradiated with 10 Gy and the rats in group 4 were irradiated with 20 Gy. Hemodynamic parameters and indices were determined from the impedance cardiography (ICG) recording in the whole groups before they were irradiated with RT and 180 days after RT. And then, interleukin-1ß, interleukin-10, TNF-α, apopthosis were determined in all groups. In addition, histological changes of heart and aorta were evaluated. RESULTS: Histopathologic, cytokine and hemodynamic findings supported that cardiac damage increased with increasing radiation dose. CONCLUSION: it is important in terms of being an alternative and supportive method to other methods to be able to detect heart diseases caused by RT with the ICG method.

Protective effect of MitoTEMPO against cardiac dysfunction caused by ischemia-reperfusion: MCAO stroke model study.

PURPOSE: Neurological impairments are the leading cause of post-stroke mortality, while stroke-related cardiovascular diseases rank second in significance. This study investigates the potential protective effects of MitoTEMPO (2,2,6,6-tetramethyl-4-[[2-(triphenylphosphonio) acetyl] amino]-1-piperidinyloxy, monochloride, monohydrate), a mitochondria-specific antioxidant, against cardiac and neurological complications following stroke. The objective is to assess whether MitoTEMPO can be utilized as a protective agent for individuals with a high risk of stroke. MATERIALS AND METHODS: Seventeen-week-old male Wistar Albino rats were randomly assigned to three groups: SHAM, ischemia-reperfusion and MitoTEMPO + ischemia-reperfusion (MitoTEMPO injection 0.7 mg/kg/day for 14 days). The SHAM group underwent a sham operation, while the ischemia-reperfusion group underwent 1-h middle cerebral artery occlusion followed by three days of reperfusion. Afterwards, noninvasive thoracic electrical bioimpedance and electrocardiography measurements were taken, and sample collection was performed for histological and biochemical examinations. RESULTS: Our thoracic electrical bioimpedance and electrocardiography findings demonstrated that MitoTEMPO exhibited a protective effect on most parameters affected by ischemia-reperfusion compared to the SHAM group. Furthermore, our biochemical and histological data revealed a significant protective effect of MitoTEMPO against oxidative damage. CONCLUSIONS: The findings suggest that both ischemia-reperfusion-induced cardiovascular abnormalities and the protective effect of MitoTEMPO may involve G-protein coupled receptor-mediated signaling mechanisms. This study was conducted with limitations including a single gender, a uniform age group, a specific stroke model limited to middle cerebral artery, and pre-scheduled only one ischemia-reperfusion period. In future studies, addressing these limitations may enable the implementation of preventive measures for individuals at high risk of stroke.

A comprehensive electrocardiographic analysis for young athletes.

ECG-based differences between athletes and sedentary adolescents are a frequently investigated subject in sports medicine. Especially, training-induced ECG variations are common in adult athletes and sustained training often leads to anatomical changes in the heart that can yield abnormalities in ECG. Therefore, ECG screening in athletes is important in diagnosis of cardiac problems of young athletes. The present work investigated the ECG characteristics of young athletes in terms of both gender and sedentary healthy young control group differences. Besides comparison between groups, analysis parameters were also investigated within the groups using correlation analysis. ECG characteristics were extracted using wavelet transform-based adaptive algorithms. Results showed that ECGs of athletes demonstrate differences related to gender and compared to young sedentary. Athletes had significantly lower heart rate; higher QTc, P, and T amplitudes; ST segment; and ST, QT, and RR intervals compared to control group (p < 0.05). Proposed new parameter, namely "scalogram" of each wave, was lower in male athletes compared to other groups (p < 0.05). Negative correlation between T wave amplitude and RR interval could be an indicator of long QT syndrome for male athletes. Furthermore, prolongation of QRS interval in athletes could be the underlying reason of changes in T wave amplitude. Findings of this study can propose indicators for understanding the possible diseases as well as help evaluate the sudden changes in athlete's heart.

Effects of Trans-Cinnamaldehyde on Reperfused Ischemic Skeletal Muscle and the Relationship to Laminin.

PURPOSE: Ischemia-reperfusion (I-R) injury is a serious problem caused by vascular trauma, tourniquet use and/or compartment syndrome. Studies have reported that skeletal muscle function is impaired due to the lower extremity I-R injury. There are insufficient studies on the treatment methods used for the recovery of dysfunction. This study is designed to investigate the effects of trans-cinnamaldehyde (TCA), a volatile oil of cinnamon structure, on the contractile dysfunction due to I-R injury of rat extensor-digitorum-longus (EDL) muscle. MATERIALS AND METHODS: Sprague-Dawley rats were randomly divided into three groups. Except for the animals in the control group, all animals received saline (3-ml/kg) or TCA solution (30-mg/kg) which was administered orally three times with an 8-h interval before ischemia. After 24-hours, experimental groups were subjected to 3-h of lower extremity ischemia followed by 5-h reperfusion period. Then, the compound muscle action potential (CMAP) and mechanical activity of muscle were recorded using the standard electro-biophysical techniques. RESULTS: There was a decrease in the maximum contractile force in I-R group compared to the control group (p < 0.05). Oxidative damage indicator (MDA) and antioxidant indicator (CAT) increased in the EDL muscle and serum samples in the I-R group (p < 0.05). Laminin expression showed a reduction in the I-R group (p < 0.05). It was seen that TCA achieve again the maximum contraction force in the EDL muscle (p < 0.05) and maintain the expression of laminin (p > 0.05). CONCLUSION: We concluded that TCA has a potential protective effect with antioxidant effects against I-R injury and may maintain laminin levels.

Electrocardiography (ECG) analysis and a new feature extraction method using wavelet transform with scalogram analysis.

Electrocardiography (ECG) signals and the information obtained through the analysis of these signals constitute the main source of diagnosis for many cardiovascular system diseases. Therefore, accurate analyses of ECG signals are very important for correct diagnosis. In this study, an ECG analysis toolbox together with a user-friendly graphical user interface, which contains the all ECG analysis steps between the recording unit and the statistical investigation, is developed. Furthermore, a new feature calculation methodology is proposed for ECG analysis, which carries distinct information than amplitudes and durations of ECG main waves and can be used in artificial intelligence studies. Developed toolbox is tested using both Massachusetts Institute of Technology-Beth Israel Hospital (MIT-BIH) Arrhythmia ECG Database and an experimentally collected dataset for performance evaluation. The results show that ECG analysis toolbox presented in this study increases the accuracy and reliability of the ECG main wave detection analysis, highly fasten the process duration compared to manual ones and the new feature set can be used as a new parameter for decision support systems about ECG based on artificial intelligence.

Effects of extremely low-frequency electromagnetic field exposure on the skeletal muscle functions in rats.

The aim of the present study was to systematically investigate the effects of chronic exposure to extremely low-frequency electromagnetic field (ELF-EMF) on electrophysiological, histological and biochemical properties of the diaphragm muscle in rats. Twenty-nine newly weaned (24 days old, 23-80 g) female (n = 15) and male (n = 14) Wistar Albino rats were used in this study. The animals were randomly divided into two groups: the control group and the electromagnetic field (EMF) group. The control group was also randomly divided into two groups: the control female group and the control male group. The EMF exposure group was also randomly divided into two groups: the ELF-EMF female group and the ELF-EMF male group. The rats in the ELF-EMF groups were exposed for 4 h daily for up to 7 months to 50 Hz frequency, 1.5 mT magnetic flux density. Under these experimental conditions, electrophysiological parameters (muscle bioelectrical activity parameters: intracellular action potential and resting membrane potential and muscle mechanical activity parameter: force-frequency relationship), biochemical parameters (Na+, K+, Cl- and Ca+2 levels in the blood serum of rats; Na+-K+ ATPase enzyme-specific activities in muscle tissue; and free radical metabolism in both muscle tissue and serum) and transmission electron microscopic morphometric parameters of the diaphragm muscle were determined. We found that chronic exposure to ELF-EMF had no significant effect on the histological structure and mechanical activity of the muscle and on the majority of muscle bioelectrical activity parameters, with the exception of some parameters of muscle bioelectrical activity. However, the changes in some bioelectrical activity parameters were relatively small and unlikely to be clinically relevant.

Does Levetiracetam Administration Prevent Cardiac Damage in Adulthood Rats Following Neonatal Hypoxia/Ischemia-Induced Brain Injury?

Cardiovascular abnormalities are widespread when a newborn is exposed to a hypoxic-ischemic injury in the neonatal period. Although the neuroprotective effects of levetiracetam (LEV) have been reported after hypoxia, the cardioprotective effects of LEV have not been documented. Therefore, we aimed to investigate whether levetiracetam (LEV) has a protective effect on cardiac-contractility and ultrastructure of heart muscle in rats exposed to hypoxia-ischemia (HI) during the neonatal period. A total of 49 seven-day-old rat pups were separated into four groups. For HI induction, a combination of right common carotid artery ligation with 8% oxygen in seven-day-old rat pups for 2 h was performed for saline, LEV100, and LEV200 groups. Just after hypoxia, LEV100 and LEV200 groups were administered with 100 mg/kg and 200 mg/kg of LEV, respectively. The arteries of rats in the control group were only detected; no ligation or hypoxia was performed. At the end of the 16th week after HI, cardiac mechanograms were recorded, and samples of tissue were explored by electronmicroscopy.While ventricular contractility in the control group was similar to LEV100, there were significant decreases in both saline and LEV200 groups (p < 0.05). Although ventricular contractile duration of the control and saline groups was found to be similar, durations in the LEV100 and LEV200 groups were significantly higher (p < 0.05). After HI, mitochondrial damage and ultrastructural deteriorative alterations in ventricles and atriums of the LEV-administered groups were significantly less severe than the saline group. The present study showed that neonatal HI caused long-term cardiac dysfunction and ultrastructural deteriorations in cardiac muscles. LEV administration just after HI might possess some protective effects against myocardial damage and contractility.

Effects of Huperzin-A on the Beta-amyloid accumulation in the brain and skeletal muscle cells of a rat model for Alzheimer's disease.

AIMS: Alzheimer's Disease (AD) is characterized by a loss of cognitive function and also the accumulation of ß-amyloid peptide (ßAP) in the brain parenchyma, which plays an important role in this disease. However, it is often also associated with the non-cognitive symptoms such as loss of muscle function (Inclusion-Body Myositis-IBM). MAIN METHODS: Sprague-Dawley rats (13 weeks-n=68) were randomly assigned into five groups: Group C: Control; Group D: d-galactose; Group O+D: Bilateral oophorectomy+d-galactose; Group O: Bilateral oophorectomy; Group O+D+H: Bilateral oophorectomy+d-galactose+Hup-A. Tissue fixation was performed with the perfusion method. The Compound Muscle Action Potential (CMAP) and mechanical muscle activity were recorded using the standard electro-biophysical techniques. Immune staining was performed with specific antibodies, and the pathological changes were examined. RNA was obtained from brain tissue samples with the Trizol Method. Then, the expression data of mature-miRNAs (rno-miR-9-5p, rno-miR-29a-3p, rno-miR-106a-5p, rno-miR-107 and rno-miR-125a-3p), which may be effective in AD, were taken with Real-Time PCR. KEY FINDINGS: Impairments occurred in behavioral tests of the rats in the O+D group. ßAP accumulation and AChE activity increased significantly in the forebrain in the O+D group compared to the C group. It was seen that Huperzine-A (Hup-A) reduced AChE activity and destructed ßAP accumulation. There was a significant decrease in the maximum contractile force at different frequencies in the O+D group and in the O group compared to the C group. SIGNIFICANCE: It was found that Hup-A contributed to the healing process in rats for damage occurring both in the brain and in the neuro-muscular system.

Effects of a tumor necrosis factor-alpha inhibitor (etanercept) on the sciatic nerve in a hypoxic ischemia-induced neonatal rat model.

BACKGROUND: Neonatal hypoxic-ischemic (HI) injury has been considered to have acute and long term deleterious effects on many tissues, including the peripheral nerve. OBJECTIVES: In this study, the effects of a tumor necrosis factor-alpha (TNF-a) inhibitor (etanercept) on peripheral nerve damage and the ultrastructure of the sciatic nerve and gastrocnemius muscle in rats exposed to HI during the neonatal period were examined. MATERIAL AND METHODS: In this study, 45 seven-day-old rats were used and they were divided into three groups. The right carotid arteries of the rats in the saline and etanercept groups were ligated and put in a hypoxia chamber containing 8% oxygen for two hours. Just after hypoxia, the etanercept group was given 10 mg/kg etanercept, but the saline group had only saline intraperitoneally. The sham group rats' carotid arteries were not ligated or put in hypoxia. The amplitude, area and latency of sciatic nerve compound motor action potential (CMAP), which mainly reflects axonopathy and myelinopathy, were measured using standard techniques in the seventeenth week following the HI. Sciatic nerve and gastrocnemius muscle were evaluated with a transmission electron microscope, and grading for myelin sheath damage was done to all groups. RESULTS: Neuropathy was seen in rats after HI. While treatment with etanercept showed a protective effect for the axons of sciatic nerve, demyelination could not be recovered with etanercept. CONCLUSIONS: This study is the first in literature to show a partial interruption of the signal through the peripheral nerve fibers caused by axonal and myelin dysfunction continuation in rats exposed to HI after birth, in the 17th week.

Determination of the effects of pulmonary arterial hypertension and therapy on the cardiovascular system of rats by impedance cardiography.

AIM: To evaluate the effects of bosentan, sildenafil, and combined therapy on the cardiovascular system using impedance cardiography (ICG) in rats with monocrotaline (MCT)-induced pulmonary arterial hypertension (PAH). METHODS: Seventy male Wistar-albino rats were randomized into five groups. A single dose of MCT was given to all rats, except to the control group. After 4 weeks, bosentan, sildenafil, and combined treatment was started and lasted for 3 weeks. The last group that developed PAH did not receive any medication. Echocardiographic evaluation was performed to determine the PAH development. Thoracic fluid content index (TFCI), stroke volume index (SI), heart rate (HR), cardiac index (CI), and myocardial contractility index (IC) were determined. All procedures were performed at the baseline and after 4 and 7 weeks. RESULTS: Echocardiographic parameters showed that the all MCT-injected rats developed PAH. There were no significant inter- and intra-group differences in TFCI, SI, and IC (P>0.05), but at the 7th week, CI value in the sildenafil-treated PAH rats was significantly higher than in other groups and HR of PAH rats with combined therapy was significantly lower than in other groups. CONCLUSION: PAH did not have an effect on LV function of rats, or if it did, the effect was compensated by physiological processes. Also, sildenafil treatment deteriorated the LV cardiac index.

Adaptation of heart to training: a comparative study using echocardiography & impedance cardiography in male & female athletes.

BACKGROUND & OBJECTIVES: Intensive regular physical exercise training is associated with a physiological changes in left ventricular (LV) morphology and functions. This cardiac remodeling observed in the athletes is associated with the specific haemodynamic requirements of the exercise undertaken. The main objective of this study is to evaluate the effect of endurance training on cardiac morphology, systolic and diastolic LV functions and haemodynamic parameters both in male and female athletes. METHODS: Seventy nine healthy athletes (age 20.0 ± 2.6 yr; 49% male) and 82 healthy sedentary adolescent (age 20.8 ± 2.2 yr, 49% male) volunteered to participate in this study. All subjects underwent transthoracic echocardiography and impedance cardiography. RESULTS: Both female and male athletes had greater LV end-diastolic cavity sizes, LV mass and stroke volume (SV) values when compared with controls. Also, in male athletes, LV mass index was higher than in female athletes. While male athletes had lower resting heart rate compared to female athletes, they had higher mean arterial blood pressure. In male athletes, basal septal and mid septal strain values were higher compared to controls. There were no significant differences in strain and peak systolic strain rate values between female athletes and controls. In male athletes, there was a weak positive correlation between SV and LV mass, basal lateral and septal strain values. In female athletes, only a weak positive correlation was found between SV and basal septal strain values. INTERPRETATION & CONCLUSIONS: Endurance-trained male and female athletes had higher LV mass, LV cavity dimensions and SV compared to sedentary controls. Although there was no difference in diastolic cardiac functions between athletes and controls, local enhanced systolic function was found with increase of SV. Both morphologic and haemodynamic differences were more evident in male athletes.

The effect of tumor necrosis factor-α inhibitor soon after hypoxia-ischemia on heart in neonatal rats.

AIMS: Perinatal hypoxic-ischemic insult has acute and long term deleterious effects on many organs including heart. Although tumor necrosis factor alpha (TNF-α) has been reported to increase soon after hypoxia, the inhibition of this mediator has not been documented. The aim of this study was to investigate the effects of a TNF-α inhibitor (etanercept) on contractility and ultrastructure of rat heart muscles exposed to hypoxia-ischemia during neonatal period. MAIN METHODS: Forty-five seven-day old rats divided into three groups were included in this study. The right carotid arteries of Saline and Etanercept groups of rats were ligated and kept in a hypoxia chamber containing 8% oxygen for 2h. Immediately after hypoxia, while Etanercept group was administered 10mg/kg etanercept, Saline group had only saline intraperitoneally. The carotid arteries of rats in Sham group were located without ligation and hypoxia. Mechanical activity of heart was recorded and tissue samples were examined by electron microscopy in the sixteenth week following the hypoxia-ischemia. KEY FINDINGS: While atrial contractile force in Etanercept group was similar to Sham group, there was significant decrease in Saline group (p<0.001). However, there was only non-significant decrease in ventricular contractility of Saline group comparing to Sham group (p>0.05). After hypoxia-ischemia, ultrastructural degenerative changes and mitochondrial damage in atriums of Etanercept group were significantly less severe than Saline group. SIGNIFICANCE: This study demonstrated that neonatal hypoxia-ischemia caused long term cardiac dysfunction and ultrastructural degenerative changes in the heart of rats. TNF-α inhibitor administration soon after hypoxia-ischemia may have heart protective effect.

Determination of acute and chronic effects of cadmium on the cardiovascular system of rats.

In this study, the systemic hemodynamics induced by acute and chronic cadmium (Cd+2) intoxication in the cardiovascular system of rats using thoracic electrical bioimpedance were examined and the acute and chronic effects of Cd+2 intoxication on the activities of antioxidant enzymes and malondialdehyde (MDA) were compared. Also, in this study, ultrastructural changes in the heart and aorta of rats were evaluated. Thirty-eight male Wistar albino rats were randomly divided into control, acute, and chronic groups. Chronic group was administered by oral gavage an aqueous solution of CdCl2 for 60 days, at dose of 15 mg Cd+2/kg/day. Acute group was administered by oral gavage an aqueous solution of CdCl2 with a single dose of 15 mg Cd+2/kg. Cadmium increased the stroke volume and cardiac output of rats in the chronic group, but did not change the heart rate significantly. Antioxidant enzymes activities and MDA level significantly increased in the chronic group. In ultrastructural examination, there were widespread degenerative changes in heart muscle cells of the chronic group but endothelial cells and smooth muscle cells in the aorta tissue samples had normal morphological features in all groups. All of the findings indicate that Cd+2 toxication can cause deformation in heart muscle cells due to an increase in free radicals and lipid peroxidation. Also, this study has confirmed that a long-term-Cd+2 exposure increased stroke volume (SV) and cardiac output (CO), but did not change the heart rate (HR).

Assessment of cadmium genotoxicity in peripheral blood and bone marrow tissues of male Wistar rats.

In this study, Cadmium (Cd) genotoxicity was investigated in both bone marrow and peripheral blood treatment using rat micronucleus technique as genotoxicity test at acute and chronic treatment in the same animals. This study evaluated the frequency of micronuclei in the peripheral blood and bone marrow of male rats treated with unique cadmium dose (15 mg/kg. body w/day) by gavage for 60 days and acute treatment for 24 h, respectively. Mitomycin C (MMC) 2 mg/kg body wt was used as a positive control. This study shows that cadmium chloride treatment significantly induced the frequency of micronucleus in polychromatic erythrocytes in both tibia bone marrow and peripheral blood (p < 0.001, p < 0.01, respectively). This increase in micronucleus frequency shows that cadmium has a genotoxic effect on bone marrow and peripheral blood at this level. Also, in order to determine cytotoxicity in bone marrow and peripheral blood, the ratio of polychromatic erythrocytes to normochromatic erythrocytes was calculated in bone marrow and peripheral blood. Cd treatment decreased this ratio in only bone marrow. The results of this study demonstrate that Cd has both toxic and genotoxic potential in bone marrow and only genotoxic potential in peripheral blood. There is a significant difference between the control group and exposed group, including acute and chronic treatment for blood Cd level (p < 0.001). No significant difference was found between acute and chronic exposure group (p > 0.05).

Effects of low dose trapidil on electrical properties of a rat peripheral nerve after crush injury.

BACKGROUND: Trapidil has been shown to possess the protective effects in the treatment of ischemia and reperfusion injury in the peripheral nervous system. The purpose of this study was to determine the effects of low dose trapidil on peripheral nerve regeneration with electrophysiological method. METHODS: The sciatic nerve was compressed for 20 sec by using a jeweler's forceps. Trapidil treatment groups were administrated a single dose of trapidil (8 mg/kg) intraperitoneally just after the injury. Electrophysiological recordings were performed in crush and crush + trapidil treatment groups on the 2nd, 7th, 15th, 30th and 45th days following the nerve injury. RESULTS: EMG recordings on the second day following the crush injury showed low values of compound motor action potentials in the gastrocnemius muscle when compared to normal values obtained in intact animals; also, the values on the second day following the crush injury were significantly different between control and trapidil-treated groups. The action potential values for both groups did not yet reach baseline values at the end of the experiment. There was no difference in the action potential amplitude, area and distal latency values between rats with crush and crush+trapidil on all days. CONCLUSION: We could not prove a neuroprotective effect of a single low dose of trapidil in rat crush injury model using electrophysiological method.

The effect of preventive use of alanyl-glutamine on diaphragm muscle function in cecal ligation and puncture-induced sepsis model.

BACKGROUND: Low muscle glutamine levels during sepsis are associated with reduced protein synthesis and elevated protein breakdown, in particular myofibrillar protein breakdown. Thus, in a cecal ligation and puncture (CLP)-induced sepsis model in the rat, we hypothesized that glutamine pretreatment would protect the diaphragm muscle function. METHODS: Eighty-four male Wistar rats weighing between 180 g and 200 g received standard amino acid solution 1.2 g kg(-1) per day intraperitoneally (IP) or standard amino acid solution 1.2 g kg(-1) per day plus alanyl-glutamine (GLN) 0.25 g kg(-1) per day (IP) during the first 6 days of the experiment. On the seventh day, CLP or sham procedures were applied. The sham and CLP groups were equally divided into 3 subgroups according to the termination of the experiment, which took place at either the 24th hour, 48th hour, or 72nd hour. After the compound muscle action potentials (CMAP) were recorded from the diaphragms of the rats at these selected times, they were decapitated under ketamine/xylazine anesthesia, and diaphragms were harvested for biochemical and histopathological examination. RESULTS: The mean area and amplitude of CMAP were significantly larger in sham+GLN groups when compared with CLP and CLP+GLN groups at all times (p < .05). Diaphragm Ca+2 -ATPase levels were found to be significantly decreased in CLP group at all times compared to sham groups (p < .05). Diaphragm reduced glutathione levels were significantly higher in sham+GLN groups when compared with CLP and CLP+GLN groups at all times (p < .05). In histopathologic assessment, moderate neutrophil infiltration, which was observed in CLP48, was significantly reduced with alanyl-glutamine supplementation in CLP+GLN48 group (p < .05). CONCLUSIONS: This study showed that glutamine pretreatment did not improve diaphragm muscle function, but prevented the biochemical and histopathological changes in diaphragmatic muscle in CLP-induced sepsis. However, further studies are needed to clarify whether a higher dose of glutamine supplementation might protect the diaphragmatic muscle functions.

Erythropoietin both protects from and reverses experimental diabetic neuropathy.

Erythropoietin (EPO) possesses generalized neuroprotective and neurotrophic actions. We tested the efficacy of recombinant human EPO (rhEPO) in preventing and reversing nerve dysfunction in streptozotocin (STZ)-induced diabetes in rats. Two days after STZ [60 mg/kg of body weight (b.w.), i.p.], diabetic animals were administered rhEPO (40 microg/kg of b.w.) three times weekly for 5 weeks either immediately (preventive) before or after a 5-week delay (therapeutic) after induction of hyperglycemia or at a lower dose (8 microg/kg of b.w. once per week) for 8 weeks (prolonged). Tail-nerve conduction velocities (NCV) was assessed at 5 and 11 weeks for the preventive and therapeutic schedule, respectively. Compared to nondiabetic rats, NCV was 20% lower after 5 weeks in the STZ group, and this decrease was attenuated 50% by rhEPO. Furthermore, the reduction of Na(+),K(+)-ATPase activity of diabetic nerves (by 55%) was limited to 24% in the rhEPO-treated group. In the therapeutic schedule, NCV was reduced by 50% after 11 weeks but by only 23% in the rhEPO-treated group. rhEPO treatment attenuated the decrease in compound muscle action potential in diabetic rats. In addition, rhEPO treatment was associated with a preservation of footpad cutaneous innervation, as assessed by protein gene product 9.5 immunostaining. Diabetic rats developed alterations in mechanical and thermal nociception, which were partially reversed by rhEPO given either in a preventative or therapeutic manner. These observations suggest that administration of rhEPO or its analogues may be useful in the treatment of diabetic neuropathy.

Reversible conduction block in isolated frog sciatic nerve by high concentration of bupivacaine.

We evaluated the effects of a high concentration of bupivacaine commonly used for spinal anaesthesia on the reversibility of conduction block and compound nerve action potential (CNAP) parameters in isolated frog sciatic nerve measured by extracellular recording technique. Isolated frog sciatic nerves were bathed in 1.3% bupivacaine solution for 20 min. In each nerve, action potentials were recorded before exposure to bupivacaine solution, which served as the control data. The extracellular action potentials were recorded after 20 min in the drug by using a BIOPAC MP 100 Acquisition System Version 3.5.7 (Santa Barbara, USA). The nerves were washed for 3h continuously with Ringer's solution and action potentials were recorded. The nerve was then soaked overnight in Ringer's solution at room temperature and tested for impulse recovery. There were significant differences among the experiments regarding CNAP peak-to-peak amplitude, area and duration but conduction velocities among the experiments did not show any statistical difference. In the presence of bupivacaine the extracellular action potential amplitude decreased by 46.99+/-29.31% relative to the control amplitude (P<0.05), recovered to 47.10+/-26.90% after 3h of wash, and reached 123.20+/-39.70% after the overnight soak process. This study showed that exposing nerve to high concentration of bupivacaine causes reversible impulse blockade and that bupivacaine does not cause neurotoxic effect on isolated frog sciatic nerve.

Acute electrophysiologic effect of pulsed gallium-arsenide low energy laser irradiation on configuration of compound nerve action potential and nerve excitability.

BACKGROUND AND OBJECTIVES: We evaluated the acute electrophysiologic effects of low-energy pulsed laser irradiation, measured by extracellular recording technique on compound action potential configuration and nerve excitability in the isolated frog sciatic nerve STUDY DESIGN/MATERIALS AND METHODS: A pulsed gallium-arsenide (GaAs) laser (wavelength, 904 nm; pulse duration, 220 nanoseconds; peak power per pulse, 27 W; spot size, 0.28 cm(2); total applied energy density, 0.005-2.5 J/cm(2)) was used for the experiment. Sixty isolated nerves were divided into six groups (n = 10), each of which received a different repetition frequency. In each group, action potentials were recorded, before laser irradiation, which served as the control data. The extracellular action potentials were recorded for each combination of 1, 3, 5, 7, 10, 13, and 15 minutes of irradiation time and 4, 8, 16, 32, 64, 128 repetition frequency by using a BIOPAC MP 100 Acquisition System Version 3.5.7 (Santa Barbara USA). Action potential latency, duration of depolarization and repolarization, and the stimulating voltage were measured. Statistical evaluation was performed using linear correlation analysis by SPSS 9.05. RESULTS: Although there was no correlation between applied energy density and action potential latency, the duration of depolarization and repolarization phases (P > 0.05), there was a weak correlation between applied energy density and stimulating voltage. CONCLUSIONS: The study showed that low-energy GaAs irradiation at 42 different energy density between 0.005 and 2.5 J/cm(2) generates no effect on action potential configuration and nerve excitability.