Plasma Creatine Phosphokinase Activity Research Articles

Characterization of plasma metabolites at late gestation and lactation in early parity sows on production and post-weaning reproductive performance1

Lactation is a very energy demanding period for sows. The current study provides a better understanding of the biochemical response of first- (n = 246) or second-parity (n = 127) sows during late gestation through lactation and assesses relationships with piglet production and dam reproductive performance. Plasma samples were collected from first- or second-parity dams at late gestation (110 d gestation [d110G]), d 1 post-farrowing (d1PF), and weaning (WN) then analyzed for various stress and protein metabolism compounds, including; creatine, creatine phosphokinase (CPK) activity, creatinine, urea nitrogen, albumin, and lactate. Litter performance was measured as number of piglets nursed and piglet ADG. Post-weaning reproductive performance was assessed by measuring weaning-to-estrus interval (WEI) and subsequent ovulation rate collected at time of harvest. Plasma creatine and CPK activity increased (P < 0.05) between d110G and d1PF. Plasma creatinine decreased (P < 0.05) from d110G through WN in first-parity dams, but remained similar between d110G and d1PF before declining (P < 0.05) at WN in second-parity dams. Plasma urea nitrogen increased (P < 0.05) over the course of the study and was negatively (P < 0.05) associated with piglet ADG at d110G and d1PF and with ovulation rate at d110G (P < 0.05). Similarly, plasma albumin increased (P < 0.05) in first-parity dams over the course of the study, whereas it plateaued (P < 0.05) at d1PF and remained similar (P > 0.10) through WN in second-parity dams. First-parity dams had less (P < 0.05) plasma lactate at d110G than at d1PF or WN. However, second-parity dams had increased (P < 0.05) plasma lactate at d110G and d1PF, then decreased (P < 0.05) levels at WN. Plasma lactate at WN was positively (P < 0.05) associated with WEI in first-parity dams, but negatively (P < 0.05) related to WEI at d1PF in second-parity dams. Plasma lactate levels at all time points were positively (P < 0.05) associated with ovulation rate in second-parity dams. The biochemical profile of these dams differed by parity and merits further investigations into these differences to identify methods to improve physiological response to lactation for improved animal welfare, production, and reproductive performance.

Preventive Effects of Ellagic Acid Against Doxorubicin-Induced Cardio-Toxicity in Mice

Preventive effects of ellagic acid against doxorubicin-induced cardiac oxidative, inflammatory and apoptotic stress were examined. This agent at 0.25, 0.5 or 1% was added in feed and supplied to mice for 8 weeks, and followed by doxorubicin treatment. Ellagic acid intake increased its deposit in heart. Pre-intake of this compound at 0.5 and 1% significantly attenuated doxorubicin caused increase in plasma creatine phosphokinase activity. Doxorubicin treatment decreased glutathione content, increased reactive oxygen species (ROS), malonyldialdehyde (MDA), interleukin (IL)-6, IL-10, monocyte chemoattractant protein-1 and tumor necrosis factor-alpha levels, declined glutathione peroxidase (GPX) and superoxide dismutase (SOD) activities, and enhanced xanthine oxidases (XO) activity in heart. Ellagic acid intake dose-dependently reserved glutathione content, lowered ROS and MDA levels, and reduced XO activity. This compound at 0.5 and 1% retained GPX and SOD activities, and decreased cytokines in heart. Doxorubicin treatment raised cardiac activity and protein production of caspase-3, nuclear factor kappa B (NF-κB) p50 and p65. Ellagic acid dose-dependently lowered caspase-3 activity and cleaved caspase-3 formation, and at 0.5 and 1% declined activity and protein level of NF-κB. Doxorubicin treatment also up-regulated cardiac expression of p-p38, p-ERK 1/2 and p-JNK, and ellagic acid at 0.5 and 1% suppressed p-p38 expression and at 1% down-regulated p-ERK 1/2 expression. These findings suggest that ellagic acid is a potent cardiac protective agent against doxorubicin.

Sulforaphane treatment protects skeletal muscle against damage induced by exhaustive exercise in rats

Sulforaphane (SF), one of the most important isothiocyanates in the human diet, present in cruciferous vegetables, is known to have chemopreventive activities in different tissues. No data are available on its effects in the prevention of skeletal muscle damage. In this study, we investigated the potential protective effects of SF treatment on muscle damage and oxidative stress induced by an acute bout of exhaustive exercise in rats. Male Wistar rats were treated with SF (25 mg/kg body wt ip) for 3 days before undergoing an acute exhaustive exercise protocol in a treadmill (+7% slope and 24 m/min). Acute exercise resulted in a significant increase in plasma lactate dehydrogenase (LDH) and creatine phosphokinase (CPK) activities. It also resulted in a significant increase in thiobarbituric acid-reactive substances, in a significant decrease in tissue total antioxidant capacity, and in a significant decrease in NAD(P)H:quinone oxidoreductase 1 (NQO1) expression and activity in vastus lateralis muscle. SF treatment significantly increased muscle NQO1, glutathione-S-transferase, and glutathione reductase expression and activity, with no effect on glutathione peroxidase and thioredoxin reductase. The observed SF-induced upregulation of phase II enzymes was accompanied by a significant increase in nuclear erythroid 2 p45-related factor 2 expression and correlated with a significant increase in total antioxidant capacity and a decrease in plasma LDH and CPK activities. Our data demonstrate that SF acts as an indirect antioxidant in skeletal muscle and could play a critical role in the modulation of the muscle redox environment, leading to the prevention of exhaustive exercise-induced muscle damage.

Combined selenium and vitamin C deficiency causes cell death in guinea pig skeletal muscle

Combined antioxidant deficiencies of selenium and vitamin E or vitamin E and vitamin C in guinea pigs result in clinical illness. We hypothesized that combined selenium and vitamin C deficiency would have clinical consequences because in vitro interactions of these antioxidant nutrients have been reported. Because guinea pigs are dependent on dietary vitamin C, weanling male guinea pigs were fed selenium-deficient or control diet for 15 weeks before imposing vitamin C deficiency. Four dietary groups were formed and studied 3 weeks later: controls, vitamin C deficient, selenium deficient, and doubly deficient. Deficiencies were confirmed by determinations of glutathione peroxidase activity and vitamin C concentration in liver and skeletal muscle. Plasma creatine phosphokinase activity and liver, kidney, heart, and quadriceps histopathology were determined. Doubly deficient animals had moderately severe skeletal muscle cell death as judged by histopathology and plasma creatine phosphokinase activity of 6630 +/- 4400 IU/L (control, 70 + or - 5; vitamin C deficient, 95 + or - 110; selenium deficient, 280 + or - 250). Liver, kidney, and heart histology was normal in all groups. Muscle alpha-tocopherol levels were not depressed in the doubly deficient group, but muscle F2 isoprostane concentrations were elevated in them and correlated with markers of cell death. We conclude that combining selenium and vitamin C deficiencies in the guinea pig causes cell death in skeletal muscle that is more severe than the injury caused by selenium deficiency. The elevation of muscle F2 isoprostanes is compatible with the cell death being caused by oxidative stress.

Effects of transport, lairage and stunning on the concentrations of some blood constituents in horses destined for slaughter

The aim of the present study was to determine, in horses destined to slaughter, the effects of transport, lairage and stunning on some blood constituents related to stress. Twenty one horses culled from a race track due to poor athletic performance, transported weekly to a nearby slaughterhouse were used. Each horse was canulated through venipuncture of the right jugular vein with a central venous catheter which remained permanently until after the exsanguination. Through the catheter, blood samples were taken at 6 sampling times: one hour before loading of the horses, immediately after loading, at the end of the journey, immediately after unloading, after lairage, in the stunning box before stunning and during exsanguination. Blood samples were analyzed for the following variables: plasma lactate concentration, plasma creatine phosphokinase activity (CK), plasma glucose concentration, plasma cortisol concentration and packed cell volume (PCV). Time in the stunning box, number of stunning attempts, presence of return to consciousness signs and time between stunning and sticking were also recorded. The results for pre-mortem variables were: mean time in the stunning box 9 min 48 sec, 85.7% of the horses fell at the first stunning attempt, 57.2% of the horses showed signs of returning to consciousness after stunning and the most frequent interval between stunning and sticking was 1.01 to 2 min. Mean values for the blood variables showed a significant rise (P < 0.05) in the concentrations of lactate, glucose and cortisol, as well as CK activity and PCV during transport. The highest values for these blood constituents were seen before stunning and during exsanguination, except for cortisol concentration, which showed the highest values during the transport process.

Protective effects of caffeic acid phenethyl ester on skeletal muscle ischemia-reperfusion injury in rats

There is a great evidence that reactive oxygen species (ROS) play an important role in the pathophysiology of ischemia-reperfusion (I/R) injury in skeletal muscle. Caffeic acid phenethyl ester (CAPE) is a component of honeybee propolis. It has antioxidant, anti-inflammatory and free radical scavenger properties. The aim of this study is to determine the protective effects of CAPE against I/R injury in respect of protein oxidation, neutrophil in filtration, and the activities of xanthine oxidase (XO) and adenosine deaminase (AD) on an in vivo model of skeletal muscle I/R injury. Rats were divided into three equal groups each consisting of six rats: Sham operation, I/R, and I/R plus CAPE (I/R+CAPE) groups. CAPE was administered intraperitoneally 60 min before the beginning of the reperfusion. At the end of experimental procedure, blood and gastrocnemius muscle tissues were used for biochemical analyses. Tissue protein carbonyl (PC) levels and the activities of XO, myeloperoxidase (MPO) and AD in I/R group were significantly higher than that of control (p < 0.01, p < 0.05, p < 0.01, p < 0.005, respectively). Administration of CAPE significantly decreased tissue PC levels, MPO and XO activities in skeletal muscle compared to I/R group (p < 0.01, p < 0.05, p < 0.05, respectively). In addition, plasma creatine phosphokinase (CPK), XO and AD activities were decreased in I/R+CAPE group compared to I/R group (p < 0.05, p < 0.05, p < 0.001). The results of this study revealed that free radical attacks may play an important role in the pathogenesis of skeletal muscle I/R injury. Also, the potent free radical scavenger compound, CAPE, may have protective potential in this process. Therefore, it can be speculated that CAPE or other antioxidant agents may be useful in the treatment of I/R injury as well as diffused traumatic injury of skeletal muscle.

Nitric oxide and prostacyclin pathways: An integrated mechanism that limits myocardial infarction progression in anaesthetized rats

Nitric oxide (NO) and cyclooxygenase-derived prostaglandins, such as prostacyclin (PGI 2), are involved in vascular homeostasis. To better understand the reciprocal role of both NO and PGI 2 on myocardial infarction in the rat, we have investigated the cardioprotective effect of nitro-naproxen, isosorbide dinitrate (ISDN), l-arginine, defibrotide and naproxen. In this study, male Wistar rats were treated orally once a day for 5 consecutive days with the compounds under investigation and then, under anesthesia, the animals were subjected to acute myocardial ischemia (30 min) and reperfusion (120 min). Systemic blood pressure, left ventricular pressure and related parameters of cardiac mechanics were recorded. Ventricular arrhythmias and infarct size of the left ventricular wall were also evaluated. Furthermore, cardiac myeloperoxidase (MPO) and plasma creatine phosphokinase (CPK) activities were determined. Defibrotide, nitro-naproxen, ISDN and l-arginine all provided a cardioprotection characterized by significant prevention of arrhythmias with high survival rate of the rats. Infarct size restriction was paralleled by reduction of both cardiac MPO and plasma CK. Cardioprotection of nitro-naproxen, ISDN and l-arginine involve nitrites/nitrates and PGI 2-increased in the circulation associated to a reduction of thromboxane B 2 (TXB 2) in the blood. Defibrotide displays a cardioprotection by increasing PGI 2 release and by reducing TXB 2 in the blood. Naproxen was devoid a lower protecting activity on myocardial infarction, and PGI 2 inhibition may have played a critical role in this context. The results suggested that the increase of both NO and PGI 2 brings about a cascade of integrated cellular and molecular events which are of paramount importance in prevention of myocardial ischemic insult.

BEHAVIORAL TRAINING AND HYDRAULIC CHUTE RESTRAINT ENABLES HANDLING OF ELAND ANTELOPE (TAUROTRAGUS ORYX) WITHOUT GENERAL ANESTHESIA

Difficulties and risks associated with restraining large nondomestic ungulates are limiting factors toward developing and applying assisted reproductive technologies, such as artificial insemination and embryo transfer. In this study on 10 female eland (Taurotragus oryx), we evaluated the use of behavioral training and handling handling in a hydraulic chute to perform transvaginal ultrasound-guided oocyte retrieval and other clinical procedures. Nine females were conditioned to associate specific sound cues with food treats. The interval from the audio cue until acceptance of handheld treats varied among females (1.8-58.3 min). Animals also differed in their response to training for voluntary entry into the chute. Handling eland for oocyte retrieval in the hydraulic chute required xylazine sedation. During sedation and handling, eland undergoing oocyte retrieval procedures had higher blood glucose levels (14.4 +/- 3.1) than females handled similarly but without oocyte retrieval (9.3 +/- 2.7 mmol/L). Plasma osmotic pressure, hematocrit, and creatine phosphokinase activity were similar between these two groups. Females that were more difficult to train had higher blood glucose levels than the more cooperative animals. Cooperative females had fewer vertical stripes on their sides. More than 40 procedures were conducted without complications or mortality. The combination of behavioral conditioning-training and restraint of sedated eland in a hydraulic chute was a reliable and repeatable method for performing minimally invasive assisted reproductive techniques.

A New Animal Model for Acute Exercise Load Utilizing “Running Neuron” Stimulation

1746 Non-athletes often suffer from muscle pain and fatigue after unaccustomed exercise. A lack of appropriate animal models makes difficult to analyze experimentally the muscle damage during acute exercise. We have reported that hyper-running behavior was inducible in rats by stimulating the “running neurons” residing in the ventromedial nucleus of the hypothalamus (VMH) with bicuculline methiodide (BMI), an antagonist to GABAA receptor. This VMH stimulation induced stereotypical running irrespective of the intention. Hence, it is feasible to set up a model for acute exercise by utilizing this hyper-running behavior. PURPOSE: To evaluate this VMH stimulation as a method to study muscle damage and fatigue in non-athletes. METHODS: At 7-weekold, male Wistar rats were assigned to two groups: the trained (n = 24) and the untrained rats (n = 25). The trained or the untrained were housed in cages with or without a running wheel, respectively, so that only the trained could run as they wished. At 8- week-old, a stainless steel guide cannula was stereotaxically inserted into the VMH. At 9-week-old, hyper-running was induced by injecting 0.5μl of BMI (500μM). After this induced running, plasma creatine phosphokinase (CPK) activity and the food intake were measured. RESULTS: When the VMH was stimulated by BMI, 12 trained and 11 untrained rats exhibited hyper-running behavior by exceeding the limit of the normal running behavior (total running time (TRT) <27min, maximum speed (MS) <16m/min, and total running distance (TRD) < 251m). In hyper-running 12 trained rats, TRT, MS, and TRD were 45.7 ± 4.0min, 43.8 ± 2.6m/min, and 727.6 ± 82.9m, respectively. In hyperrunning 11 untrained rats, TRT, MS, and TRD were 44.0 ± 3.2min, 31.5 ± 1.9m/min, and 502.4 ± 34.4m, respectively. Plasma CPK activities in both groups were elevated above the resting levels after the hyper-running. The increase was much greater (P ≤ 0.05) in the untrained (2.0-fold increase in the trained and 5.9-fold in the untrained after two hrs). Post-exercise food intake was reduced in both groups, and the reduction was larger (P ≤ 0.01) in the untrained (−36% in untrained and −13% in the trained). CONCLUSIONS: When hyper-running behavior of trained and untrained rats was compared, untrained rats ran more slowly (P≤ 0.01) and shorter distance (P ≤ 0.05) with nearly identical running time. However, it was evident that both muscle damage (plasma CPK activity) and exercise-induced fatigue (post-exercise food intake) were more severe in untrained rats. Therefore, the VMH stimulation is an appropriate model to study muscle damage and fatigue resulting from acute exercise, particularly with non-athletes.

Octacosanol Supplementation Increases Running Endurance Time and Improves Biochemical Parameters After Exhaustion in Trained Rats

This study evaluated the effects of octacosanol on running performance and related biochemical parameters in exercise-trained rats run to exhaustion on a treadmill. Male Sprague-Dawley rats were randomly assigned to one of three groups - sedentary control group (SC), exercise-trained control group (EC), and exercise-trained, octacosanol-supplemented group (EO) - and raised on either control or octacosanol (0.75%)-supplemented diet with (or without for SC rats) exercise-training for 4 weeks. EC rats ran 184% longer until exhaustion than SC rats (P <.01), while octacosanol-supplemented trained rats ran 46% longer than EC rats (P <.05). Under the exhausted state immediately following the running performance test, EO rats exhibited significantly higher plasma ammonia and lactate concentrations compared with the values for EC rats (P <.05). Although EO rats ran significantly longer until exhausted, their plasma glucose level and gastronecmius muscle glycogen concentration were not significantly different from those of EC rats. Dietary supplementation of octacosanol resulted in significantly higher creatine phosphokinase activity in plasma (44% increase, P <.01) and citrate synthase activity in muscle (16% increase, P<.01) of exercise-trained rats. These results suggest that the ergogenic properties of octacosanol include the sparing of muscle glycogen stores and increases in the oxidative capacity in the muscle of exercise-trained rats.

Hematology, plasma chemistry, serology, and Chlamydophila status of the waved albatross (Phoebastria irrorata) on the Galapagos Islands.

Venipuncture was performed on 50 adult, free-ranging waved albatrosses (Phoebastria irrorata) on Española, Galapagos Islands, Ecuador, to establish hematologic and plasma biochemistry reference ranges and to determine the prevalence of exposure to important domestic avian pathogens. Weights and plasma creatine phosphokinase activities differed significantly between males and females. Serum was tested for evidence of exposure to avian influenza, avian paramyxoviruses 1, 2, and 3, avian cholera, adenovirus groups 1 and 2, avian encephalomyelitis, Marek's disease, infectious bursal disease, and infectious bronchitis virus (Connecticut and Massachusetts strains). Of 44 birds, 29 (66%) seroreacted to adenovirus group 1, and four seroreacted to avian encephalomyelitis. Cloacal swabs were negative for Chlamydophila psittaci DNA.

Attenuation of Isoproterenol-mediated Myocardial Injury in Rat by an Inhibitor of Polyamine Synthesis

Objective: Ornithine decarboxylase (ODC) is an initial rate-limiting enzyme in the synthesis of polyamines (putrescine, spermidine, and spermine) that play a role in cell growth and differentiation. Recent studies have shown that spermidine and spermine cause injury to a variety of cells including myocytes in vitro. In this investigation, we used α-difluoromethylornithine (DFMO), a specific and irreversible inhibitor of ODC activity and polyamine synthesis to test the hypothesis that polyamines contribute to myocardial injury in rat. Methods: Male Sprague Dawley rats were treated with (i) saline (0.2 ml/day, s.c.), (ii) isoproterenol (ISO) (5 mg/kg/day for 8 days, s.c.) to produce necrotizing myocardial injury, or with (iii) DFMO + ISO. DFMO was started 2 days before the initiation of ISO and both ISO and DFMO were continued until the end of the experimental period. Myocardial injury was assessed by determining the increased release of creatine phosphokinase (CPK) and lactate dehydrogenase (LDH) into the plasma, and by morphometric analysis of the lesion area in heart sections stained with Gomori trichrome. Results: ISO induced the release of CPK and LDH by 6 hr and 24 hr, respectively, and produced subendocardial necrosis, which was both acute and resolving following 8 days of ISO. DFMO treatment inhibited ISO-induced increases in (i) ODC activity and putrescine and spermidine levels in heart, (ii) CPK and LDH activity in plasma, and (iii) the area of subendocardial lesions. Conclusions: These observations suggest that polyamines are one of the intracellular factors that contribute to ISO-mediated cardiac injury in the rat.

Interactive and delayed effects of pyridostigmine and physical stress on biochemical and histological changes in peripheral tissues of mice

Gulf War veterans were taking pyridostigmine orally against possible exposure to nerve agents as well as being under physical stress. This study was designed to investigate the delayed effects of pyridostigmine and treadmill exercise on cholinesterase activity, lipid peroxidation and histology of peripheral tissues of mice. Male NIH Swiss mice were divided into four groups of 15 animals each and treated as follows: sedentary control; exercise training for 10 weeks; pyridostigmine (1.2 mg kg−1, p.o.) for 2 weeks during weeks 5 and 6; and pyridostigmine plus exercise training. The mice were sacrificed 24 h after the last exercise, and blood, triceps muscle and sciatic nerve were isolated and analyzed. The group treated with pyridostigmine alone showed decreased plasma butyrylcholinesterase (BChE) activity (87% of control), whereas pyridostigmine plus exercise significantly decreased the BChE activity (79% of control), indicating an interactive effect of the combination. Acetylcholinesterase (AChE) activity did not alter significantly in red blood cells, platelets or sciatic nerve with either of the treatments. However, AChE activity in triceps muscle decreased significantly (78% of control) in the group treated with pyridostigmine plus exercise. Creatine phosphokinase activity in plasma increased slightly (compared to control, pyridostigmine or exercise group) in mice treated with pyridostigmine plus exercise, which may be indicative of perturbation in the integrity of the skeletal muscle due to combination. However, there were no obvious histological abnormalities in the triceps muscle detected between experimental and control groups. Interaction of pyridostigmine and exercise significantly increased the concentration of the end product of lipid peroxidation (malondialdehyde) (124% of control) in triceps muscle, indicating an oxidative stress response of the combination. These results indicate that physical stress enhanced the delayed toxic effects of a subchronic oral dose of pyridostigmine primarily in the skeletal muscle of mice. Copyright © 2000 John Wiley & Sons, Ltd.

Influence of one bout of vigorous exercise on ascorbic acid in plasma and oxidative damage to DNA in blood cells and muscle in untrained rats

We investigated the influence of a single exhaustive bout of downhill running on oxidative damage to DNA and changes of antioxidant vitamin concentrations in rats. Plasma vitamin E levels were unchanged up to 48 hr postexercise. However, plasma ascorbic acid (AA) levels increased after the exercise, then decreased thereafter. This increase corresponded to a marked decrease in AA concentration in the adrenal glands. The activity of hepatic l-gulono-γ-lactone oxidase, which catalyzes AA synthesis, was unaltered after the exercise. The weight of the adrenal glands was significantly increased 24 hr postexercise. These results indicate that the change in the plasma AA concentration after vigorous exercise was due mainly to the release of AA from the adrenal glands. The plasma creatine phosphokinase (CPK) activity and white blood cell (WBC) count increased 3 to 6 hr postexercise. Over this same period, a marker of oxidative DNA damage, 8-hydroxydeoxyguanosine in DNA, increased in the WBC, but not in the foreleg muscle. Lipid peroxide and vitamin E levels were also unchanged in the foreleg muscle. There was a positive correlation between CPK activity in the plasma and DNA damage in the WBC, suggesting that the DNA damage in the WBC was closely related with muscle damage due to exercise.

Interactive and delayed effects of pyridostigmine and physical stress on biochemical and histological changes in peripheral tissues of mice.

Gulf War veterans were taking pyridostigmine orally against possible exposure to nerve agents as well as being under physical stress. This study was designed to investigate the delayed effects of pyridostigmine and treadmill exercise on cholinesterase activity, lipid peroxidation and histology of peripheral tissues of mice. Male NIH Swiss mice were divided into four groups of 15 animals each and treated as follows: sedentary control; exercise training for 10 weeks; pyridostigmine (1.2 mg kg(-1), p.o.) for 2 weeks during weeks 5 and 6; and pyridostigmine plus exercise training. The mice were sacrificed 24 h after the last exercise, and blood, triceps muscle and sciatic nerve were isolated and analyzed. The group treated with pyridostigmine alone showed decreased plasma butyrylcholinesterase (BChE) activity (87% of control), whereas pyridostigmine plus exercise significantly decreased the BChE activity (79% of control), indicating an interactive effect of the combination. Acetylcholinesterase (AChE) activity did not alter significantly in red blood cells, platelets or sciatic nerve with either of the treatments. However, AChE activity in triceps muscle decreased significantly (78% of control) in the group treated with pyridostigmine plus exercise. Creatine phosphokinase activity in plasma increased slightly (compared to control, pyridostigmine or exercise group) in mice treated with pyridostigmine plus exercise, which may be indicative of perturbation in the integrity of the skeletal muscle due to combination. However, there were no obvious histological abnormalities in the triceps muscle detected between experimental and control groups. Interaction of pyridostigmine and exercise significantly increased the concentration of the end product of lipid peroxidation (malondialdehyde) (124% of control) in triceps muscle, indicating an oxidative stress response of the combination. These results indicate that physical stress enhanced the delayed toxic effects of a subchronic oral dose of pyridostigmine primarily in the skeletal muscle of mice.

Poly(rac-lactide) nanocapsules containing diclofenac: protection against muscular damage in rats

The aim of this work was to determine whether encapsulation of a non steroidal antiinflammatory agent within nanocapsules could reduce local toxicity after intramuscular injection. Diclofenac-loaded nanocapsules were prepared by deposition of poly( rac -lactic acid) polymer, and administered intramuscularly to male Wistar rats. Plasma creatine phosphokinase (CPK) activity and histological examination were used to assess local tissue damage. Following a single intramuscular injection of diclofenac (0.8 mg), CPK activity was shown to depend on both the type of dosage form and, in the case of nanocapsules, on the chemical nature of the central oily core. Lower CPK activity was observed with nanocapsules prepared from Miglyol 810fi, a caprylic/capric triglyceride, while nanocapsules prepared from benzyl benzoate, either empty or containing diclofenac, exhibited the same CPK activity as the drug solution. Histopathological examination performed three days after administration of free diclofenac or nanocapsules containing diclofenac prepared from Miglyol 810fi revealed that a much more intense inflammation was obtained with the solution than with nanocapsules. In conclusion, when appropriately formulated, nanocapsules can considerably reduce the muscular damage caused by diclofenac.

??-HYDROXY-??-METHYLBUTYRATE SUPPLEMENTATION DURING RESISTANCE TRAINING

2069 The purpose of this investigation was 1) to validate previous research demonstrating that β-hydroxy-β-methylbutyrate (HMB) increases fat free mass (FFM) and strength during resistance training (RT) and 2) determine if a higher dose of HMB provides additional benefits. Thirty-seven, untrained, college-aged males were assigned to one of three groups: 0, 38, or 76 mg·kg−1·d−1 of HMB. The mean weights were 77.2, 76.1, and 81.7 kg for the 0, 38, and 76 mg·kg−1·d−1 groups, respectively. RT consisted of 10 different exercises performed 3 d·wk−1 for eight weeks at 80% of 1-repetition maximum (1RM). The 1RM was re-evaluated every two weeks with workloads adjusted accordingly. No differences were observed in 1RM strength among the groups. However, lower body strength increased by 14% and 10% for the 38 and 76 mg·kg−1·d−1 group, respectively, as compared to the 0 mg·kg−1·d−1 group. The 38 mg·kg−1·d−1 group elicited a greater increase in peak isometric torque than the 0 or 76 mg·kg−1·d−1 groups (p<0.05). The 76 mg·kg−1·d−1 group had a greater increase in peak isokinetic torque than the 0 or 38 mg·kg−1·d−1 groups at 2.1, −3.15, and −4.2 rads·sec−1 (p<0.05). No differences were observed in body fat. However, the 38 mg·kg−1·d−1 group exhibited a greater increase in FFM (0.02, 1.96, and −0.17 kg for the 0, 38, or 76 mg·kg−1·d−1, respectively, p=0.051). The plasma creatine phosphokinase activity (an estimator of muscle breakdown) showed a greater increase for the 0 mg·kg−1·d−1 vs the 38 or 76 mg·kg−1·d−1 groups at 48 hours after the initial training bout (p<0.05). Although the 1RM strength gains were not significantly different, HMB appears to increase FFM and inhibit muscle breakdown. Lastly, it appears that higher doses of HMB (>38 mg·kg−1·d−1) does not promote strength or FFM gains. Supported in part by a grant from MTI and EAS.

Effect of chronic K+ deficiency on contractile properties of soleus muscle in rats: evidence of sex differences.

1. Alterations in skeletal muscle function of chronically K(+)-depleted male and female rats were investigated in isolated soleus muscles. 2. By 16 weeks K+ deficiency, plasma K+ concentrations in both male and female rats were reduced to approximately 2 mEq/L, which was accompanied by an approximate 50% reduction in muscle K+ content and a marked increase in muscle Na+ content. These changes were similar in both males and females. 3. Plasma creatine phosphokinase activity progressively increased with time in K(+)-depleted male rats, whereas only a slight increase was observed in female rats. 4. Maximum isometric twitch tension (Pt) and tetanic tension (Po) of K(+)-depleted soleus muscles from male rats was markedly suppressed; this was not seen for soleus muscles obtained from female rats. 5. After exposure to insulin in low-K+ solution, the contractile tension of soleus from the K(+)-depleted male rats was suppressed to a greater extent. 6. All alterations in muscle function during chronic K+ depletion were restored to normal after 2 weeks K+ repletion. 7. The results suggest that there is a preponderance for male over female rats in developing alterations in skeletal muscle function during chronic K+ deficiency. The changes may be associated with abnormalities of muscle membrane permeability and cellular function.

Effect of Cremophor EL on the pharmacokinetics, antitumor activity and toxicity of doxorubicin in mice.

Cremophor EL (CR) is a solubilizing agent and a modulator of P-glycoprotein (P-gp)-mediated anticancer multidrug resistance. The present study was undertaken to evaluate whether doxorubicin (Dox) pharmacokinetics, therapeutic activity and cardiotoxicity in Swiss albino mice is modified when combined with CR treatment. CR (2.5 ml/kg, i.p) given simultaneously with Dox (20 mg/kg, i.p.) increased Dox levels in plasma, heart, liver and kidneys of healthy mice. Using an Ehrlich ascites carcinoma (EAC)-bearing mice experimental model, CR (2.5 ml/kg) improved the survival and antitumor activity of Dox. The enhanced antitumor activity of Dox was related to a significant increase in EAC tumor cellular Dox content by CR. Furthermore, CR (1 microg/ml) potentiated the in vitro cytotoxicity of Dox in cultured EAC cells. In healthy mice, Dox-induced mortality was markedly reduced by simultaneous treatment with CR. CR enhanced DOX-induced increase in plasma lactate dehydrogenase, creatine phosphokinase (CPK) and CPK-MB isozyme activities, as well as the cardiac malondialdehyde level. CR also increased Dox-induced focal necrotic myocardial lesions. These findings suggest that CR increased DOX antitumor activity and cardiotoxicity as a result of enhancing its bioavailability, and decreased Dox-induced mortality in mice by a mechanism not yet defined.

Protection against myocardial ischemia and reperfusion injury by 3-aminobenzamide, an inhibitor of poly (ADP-ribose) synthetase.

Peroxynitrite and hydroxyl radical, reactive oxidants produced during reperfusion, are potent triggers of DNA single strand breakage. DNA injury triggers the activation of the nuclear enzyme poly (ADP-ribose) synthetase (PARS), which contributes to cellular energetic depletion. Using 3-aminobenzamide, an inhibitor of PARS, we investigated the role of PARS in the pathogenesis of myocardial reperfusion injury in a rat model. Occlusion of the left main coronary artery (one hour) followed by reperfusion (one hour) in the anesthetized rat caused severe cardiac necrosis, neutrophil infiltration, and increased plasma creatine phosphokinase activity. There was significant peroxynitrite production during reperfusion, as indicated by a massive increase in nitrotyrosine in the necrotic myocardium. Reperfusion was also associated with a significant loss of myocardial ATP. In vivo administration of the PARS inhibitor 3-aminobenzamide (10 mg/kg i.v.) to rats subjected to myocardial ischemia and reperfusion, reduced myocardial infarct size and blunted the increase in plasma creatine phosphokinase activity and myeloperoxidase activity in infarcted hearts. In addition, 3-aminobenzamide partially preserved the myocardial ATP levels. In vitro, pharmacological inhibition of PARS also ameliorated peroxynitrite-induced cytotoxicity in rat cardiac myocytes and human endothelial cells. 3-aminobenzamide has significant protective effects in myocardial reperfusion injury. We hypothesize that activation of PARS activation plays a role in the pathophysiology of acute myocardial infarction.