scholarly journals Comparison of the in-vivo Effect of Two Tranexamic Acid Doses on Fibrinolysis Parameters in Adults Undergoing Valvular Cardiac Surgery with Cardiopulmonary Bypass - A Pilot Investigation

2020 ◽  
Author(s):  
Zhen-feng ZHOU ◽  
Wen Zhai ◽  
Li-na YU ◽  
Kai SUN ◽  
Li-hong SUN ◽  
...  
Keyword(s):  
Cardiac Surgery ◽  
Placebo Group ◽  
Cardiopulmonary Bypass ◽  
Plasminogen Activator ◽  
Dose Group ◽  
Low Dose ◽  
High Dose Group ◽  
High Dose ◽  
Pai 1

Abstract Background: The blood saving efficacy of TXA in cardiac surgery has been proved in several studies, but TXA dosing regimens were varied in those studies. Therefore, we performed this study to investigate if there is a dose dependent in-vivo effect of TXA on fibrinolysis parameters by measurement of fibrinolysis markers in adults undergoing cardiac surgery with CPB, which has not been systematically elucidated.Methods: A double-blind, randomized, controlled prospective trial was conducted from February 11, 2017 to May 05, 2017. Thirty patients undergoing cardiac valve surgery were identified and randomly divided into a placebo group, low-dose group and high-dose group by 1: 1: 1. Fibrinolysis parameters were measured by plasma levels of D-Dimers, plasminogen activator inhibitor-1 (PAI-1), thrombin activatable fibrinolysis inhibitor (TAFI), plasmin-antiplasmin complex (PAP), tissue plasminogen activator (tPA) and thrombomodulin (TM). Those proteins were measured at five different sample times: preoperatively before the TXA injection (T1), 5 min after the TXA bolus (T2), 5 min after the initiation of CPB (T3), 5 min before the end of CPB (T4) and 5 min after the protamine administration (T5). A Thrombelastography (TEG) and standard coagulation test were also performed.Results: Compared with the control group, the level of the D-Dimers decreased in the low-dose and high-dose groups when the patients arrived at the ICU and on the first postoperative morning. Over time, the concentrations of PAI-1, TAFI, and TM, but not PAP and tPA, showed significant differences between the three groups (p <0.05). Compared with the placebo group, the plasma concentrations of PAI-1 and TAFI decreased significantly at the T3 and T4 (p <0.05); TAFI concentrations also decreased at the T5 in low-dose group (p <0.05). Compared with the low-dose group, the concentration of TM increased significantly at the T4 in high-dose group. No significant differences were observed in the levels of the coagulation proteins at any points between the groups.Conclusions: The vivo effect of low dose TXA is equivalent to high dose TXA on fibrinolysis parameters in adults undergoing valvular cardiac surgery with cardiopulmonary bypass, and we recommend a low dose TXA regimen for those patients.Clinical trial number and registry URL: ChiCTR-IPR-17010303; http://www.chictr.org.cn, Principal investigator: Zhen-feng ZHOU, Date of registration: January 1, 2017.

scholarly journals Comparison of the in-vivo effect of two tranexamic acid doses on fibrinolysis parameters in adults undergoing valvular cardiac surgery with cardiopulmonary bypass - a pilot investigation

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Zhen-feng Zhou ◽  
Wen Zhai ◽  
Li-na Yu ◽  
Kai Sun ◽  
Li-hong Sun ◽  
...  
Keyword(s):  
Cardiac Surgery ◽  
Placebo Group ◽  
Cardiopulmonary Bypass ◽  
Plasminogen Activator ◽  
Dose Group ◽  
Low Dose ◽  
High Dose Group ◽  
High Dose ◽  
Pai 1

Abstract Background The blood saving efficacy of TXA in cardiac surgery has been proved in several studies, but TXA dosing regimens were varied in those studies. Therefore, we performed this study to investigate if there is a dose dependent in-vivo effect of TXA on fibrinolysis parameters by measurement of fibrinolysis markers in adults undergoing cardiac surgery with CPB. Methods A double-blind, randomized, controlled prospective trial was conducted from February 11, 2017 to May 05, 2017. Thirty patients undergoing cardiac valve surgery were identified and randomly divided into a placebo group, low-dose group and high-dose group by 1: 1: 1. Fibrinolysis parameters were measured by plasma levels of D-Dimers, plasminogen activator inhibitor-1 (PAI-1), thrombin activatable fibrinolysis inhibitor (TAFI), plasmin-antiplasmin complex (PAP), tissue plasminogen activator (tPA) and thrombomodulin (TM). Those proteins were measured at five different sample times: preoperatively before the TXA injection (T1), 5 min after the TXA bolus (T2), 5 min after the initiation of CPB (T3), 5 min before the end of CPB (T4) and 5 min after the protamine administration (T5). A Thrombelastography (TEG) and standard coagulation test were also performed. Results Compared with the control group, the level of the D-Dimers decreased in the low-dose and high-dose groups when the patients arrived at the ICU and on the first postoperative morning. Over time, the concentrations of PAI-1, TAFI, and TM, but not PAP and tPA, showed significant differences between the three groups (P <  0.05). Compared with the placebo group, the plasma concentrations of PAI-1 and TAFI decreased significantly at the T3 and T4 (P <  0.05); TAFI concentrations also decreased at the T5 in low-dose group (P < 0.05). Compared with the low-dose group, the concentration of TM increased significantly at the T4 in high-dose group. Conclusions The in-vivo effect of low dose TXA is equivalent to high dose TXA on fibrinolysis parameters in adults with a low bleeding risk undergoing valvular cardiac surgery with cardiopulmonary bypass, and a low dose TXA regimen might be equivalent to high dose TXA for those patients. Trial registration ChiCTR-IPR-17010303, Principal investigator: Zhen-feng ZHOU, Date of registration: January 1, 2017.

Postoperative Hemostasis and Fibrinolysis in Patients Undergoing Cardiopulmonary Bypass with or without Aprotinin Therapy

1994 ◽  
Vol 72 (03) ◽  
pp. 438-443 ◽  
Author(s):  
He Lu ◽  
Charles Du Buit ◽  
Jeannette Soria ◽  
Bernard Touchot ◽  
Bernard Chollet ◽  
...  
Keyword(s):  
Placebo Group ◽  
Cardiopulmonary Bypass ◽  
Blood Loss ◽  
Plasminogen Activator ◽  
Fold Increase ◽  
Tissue Type ◽  
Postoperative Blood Loss ◽  
High Dose ◽  
Double Blind Study ◽  
Pai 1

SummaryIntra- and postoperative blood loss during open heart surgery is reduced by approximately 50% when aprotinin, a potent inhibitor for plasmin and kallikrein, is administered during surgery. But whether aprotinin increases the risk of thrombotic complications remains controversial. The aim of this study was to evaluate the effects of aprotinin administration on coagulation and fibrinolysis during and after cardiopulmonary bypass (CPB). Thirty patients undergoing CPB were randomly assigned to two comparable groups for a double-blind study (16 patients receiving high-dose aprotinin, 14 patients receiving placebo). Patients’ plasma levels of ATM (thrombin-induced modified antithrombin III), FbDP (fibrin degradation products, D-Dimers), t-PA (tissue-type plasminogen activator) and PAI-1 (plasminogen activator inhibitor type 1) were measured at regular intervals. In both groups, ATM level increased during surgery (from less than 30 to 90-110 ng/ml) and returned to normal 24 h after surgery and remained unchanged thereafter. Aprotinin reduced this increase in ATM levels (p = 0.02 at 30 min after the start of CPB). The FbDP generated during surgery was greatly reduced in the aprotinin group (945 ng/ml) in comparison with the placebo group (1889 ng/ml, p = 0.004). After surgery, FbDP levels decreased in both groups with nadirs at 2nd day (placebo group: 940 ng/ml and aprotinin group: 865 ng/ml) indicating a hypo-fibrinolytic period. Then, the FbDP level in both groups started to increase up to the 9th day, in an identical manner. This postoperative hypofibrinolysis is related to the changes of t-PA and PAI-1 levels: immediately after surgery there was a 2’fold increase in t-PA level and a 4-5 fold increase in PAI-1 level in the two groups. During the following 24 h, t-PA levels decreased in both groups. In contrast, PAI-1 levels in the placebo group during the same time increased sharply to a maximum level (175.7 ng/ml). This further increase did not occur in the aprotinin group although it remained at a high level (79.2 ng/ml). The difference in the increase of PAI-1 between the 2 groups (value at 24 h minus preoperative value: Dl-Tl) was significantly different (p = 0.04). Then t-PA continued to decrease and PAI-1 began to decrease steadily. Total blood loss was significantly reduced by aprotinin therapy (3.06 ml/kg versus 5.86 ml/kg). The present study confirms the inhibitory effects of aprotinin on both fibrinolytic activity and blood coagulation activation during CPB, and reveals an hypofibrinolytic period that lasts 48 h after surgery in both aprotinin and placebo groups. This inhibition of fibrinolysis is apparently associated with high PAI-1 level. The data of this study also show that 2 days after aprotinin therapy, there is no prolonged effect of aprotinin on fibrinolysis. In addition, the lower level of PAI-1 in the aprotinin group after surgery might result from a protection of endothelial cells by aprotinin, suggesting an unexpected benefit of aprotinin therapy.

scholarly journals Serum lipid-improving effect of soyabean β-conglycinin in hyperlipidaemic menopausal women

2013 ◽  
Vol 110 (9) ◽  
pp. 1680-1684 ◽  
Author(s):  
Defu Ma ◽  
Kyoko Taku ◽  
Yumei Zhang ◽  
Meng Jia ◽  
Yang Wang ◽  
...  
Keyword(s):  
Placebo Group ◽  
Dose Group ◽  
Low Dose ◽  
Ldl Cholesterol ◽  
Cholesterol Concentration ◽  
High Dose Group ◽  
High Dose ◽  
Cholesterol Levels ◽  
Menopausal Women ◽  
Effect Of Treatment

To evaluate the effect of treatment with β-conglycinin, a major soyabean protein, on blood lipids in menopausal women, we recruited 100 hyperlipidaemic women aged 40–60 years old. Participants were randomly allocated to three groups: placebo group (n 34, four casein tablets/d); low dose group (n 33, four tablets containing 2·3 g β-conglycinin/d); high-dose group (n 33, eight tablets containing 4·6 g β-conglycinin/d). The mean serum TAG concentration was significantly reduced after 6 and 12 weeks of β-conglycinin intervention by 0·44 (sd 0·20) and 0·78 (sd 1·03) mmol/l in the low-dose group, and by 0·46 (sd 0·17) and 1·25 (sd 1·06) mmol/l in the high-dose group, respectively. One-way ANOVA revealed that serum TAG concentrations in the low-dose and high-dose groups were significantly lowered compared with the placebo group at weeks 6 and 12 (P< 0·05). The low dose and high dose consumptions of β-conglycinin significantly decreased the LDL-cholesterol concentration by 0·46 (sd 0·72) and 0·52 (sd 0·97) mmol/l at week 12, respectively (P< 0·05). Compared with the changes from baseline in the placebo group, apoB and NEFA were significantly lowered in both the low-dose and high-dose β-conglycinin groups (P< 0·05). In conclusion, the results suggest that β-conglycinin intake significantly decreases serum TAG and LDL-cholesterol levels.

scholarly journals Newly Developed Recombinant Antithrombin Protects the Endothelial Glycocalyx in an Endotoxin-Induced Rat Model of Sepsis

2020 ◽  
Vol 22 (1) ◽  
pp. 176
Author(s):  
Toshiaki Iba ◽  
Jerrold H. Levy ◽  
Koichiro Aihara ◽  
Katsuhiko Kadota ◽  
Hiroshi Tanaka ◽  
...  
Keyword(s):  
Dose Group ◽  
Low Dose ◽  
Leukocyte Adhesion ◽  
Endothelial Glycocalyx ◽  
High Dose Group ◽  
Control Group ◽  
High Dose ◽  
Protective Effects ◽  
Circulating Levels

(1) Background: The endothelial glycocalyx is a primary target during the early phase of sepsis. We previously reported a newly developed recombinant non-fucosylated antithrombin has protective effects in vitro. We further evaluated the effects of this recombinant antithrombin on the glycocalyx damage in an animal model of sepsis. (2) Methods: Following endotoxin injection, in Wistar rats, circulating levels of hyaluronan, syndecan-1 and other biomarkers were evaluated in low-dose or high-dose recombinant antithrombin-treated animals and a control group (n = 7 per group). Leukocyte adhesion and blood flow were evaluated with intravital microscopy. The glycocalyx was also examined using side-stream dark-field imaging. (3) Results: The activation of coagulation was inhibited by recombinant antithrombin, leukocyte adhesion was significantly decreased, and flow was better maintained in the high-dose group (both p < 0.05). Circulating levels of syndecan-1 (p < 0.01, high-dose group) and hyaluronan (p < 0.05, low-dose group; p < 0.01, high-dose group) were significantly reduced by recombinant antithrombin treatment. Increases in lactate and decreases in albumin levels were significantly attenuated in the high-dose group (p < 0.05, respectively). The glycocalyx thickness was reduced over time in control animals, but the derangement was attenuated and microvascular perfusion was better maintained in the high-dose group recombinant antithrombin group (p < 0.05). (4) Conclusions: Recombinant antithrombin maintained vascular integrity and the microcirculation by preserving the glycocalyx in this sepsis model, effects that were more prominent with high-dose therapy.

scholarly journals Spatio-temporal biodistribution of 89Zr-oxine labeled huLym-1-A-BB3z-CAR T-cells by PET imaging in a preclinical tumor model

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Naomi S. Sta Maria ◽  
Leslie A. Khawli ◽  
Vyshnavi Pachipulusu ◽  
Sharon W. Lin ◽  
Long Zheng ◽  
...  
Keyword(s):  
T Cells ◽  
Real Time ◽  
Pet Imaging ◽  
Dose Group ◽  
Low Dose ◽  
High Dose ◽  
Car T Cells ◽  
Nsg Mice ◽  
Car T

AbstractQuantitative in vivo monitoring of cell biodistribution offers assessment of treatment efficacy in real-time and can provide guidance for further optimization of chimeric antigen receptor (CAR) modified cell therapy. We evaluated the utility of a non-invasive, serial 89Zr-oxine PET imaging to assess optimal dosing for huLym-1-A-BB3z-CAR T-cell directed to Lym-1-positive Raji lymphoma xenograft in NOD Scid-IL2Rgammanull (NSG) mice. In vitro experiments showed no detrimental effects in cell health and function following 89Zr-oxine labeling. In vivo experiments employed simultaneous PET/MRI of Raji-bearing NSG mice on day 0 (3 h), 1, 2, and 5 after intravenous administration of low (1.87 ± 0.04 × 106 cells), middle (7.14 ± 0.45 × 106 cells), or high (16.83 ± 0.41 × 106 cells) cell dose. Biodistribution (%ID/g) in regions of interests defined over T1-weighted MRI, such as blood, bone, brain, liver, lungs, spleen, and tumor, were analyzed from PET images. Escalating doses of CAR T-cells resulted in dose-dependent %ID/g biodistributions in all regions. Middle and High dose groups showed significantly higher tumor %ID/g compared to Low dose group on day 2. Tumor-to-blood ratios showed the enhanced extravascular tumor uptake by day 2 in the Low dose group, while the Middle dose showed significant tumor accumulation starting on day 1 up to day 5. From these data obtained over time, it is apparent that intravenously administered CAR T-cells become trapped in the lung for 3–5 h and then migrate to the liver and spleen for up to 2–3 days. This surprising biodistribution data may be responsible for the inactivation of these cells before targeting solid tumors. Ex vivo biodistributions confirmed in vivo PET-derived biodistributions. According to these studies, we conclude that in vivo serial PET imaging with 89Zr-oxine labeled CAR T-cells provides real-time monitoring of biodistributions crucial for interpreting efficacy and guiding treatment in patient care.

scholarly journals Recombinant Human Thyrotropin-Stimulated Radioiodine Therapy in Patients with Multinodular Goiters: A Meta-Analysis of Randomized Controlled Trials

2020 ◽  
Vol 52 (12) ◽  
pp. 841-849
Author(s):  
Chunmei Xu ◽  
Ping Wang ◽  
Huikai Miao ◽  
Tianyue Xie ◽  
Xiaojun Zhou ◽  
...  
Keyword(s):  
Fixed Effects ◽  
Dose Group ◽  
Low Dose ◽  
Radioiodine Therapy ◽  
Meta Analysis ◽  
High Dose Group ◽  
High Dose ◽  
Fixed Effects Model ◽  
Recombinant Human Thyrotropin

AbstractA potential reduction of goiter volume (GV) of recombinant human thyrotropin (rhTSH) on multinodular goiters (MNG) was previously reported but controversial. Hence we conducted a meta-analysis to estimate the effect of rhTSH-stimulated radioiodine therapy in patients with MNG. PubMed, Cochrane, CNKI, VIP, and Wanfang databases were searched. Mean difference (MD) and odds ratios with 95% confidence intervals (95% CI) were derived by using an inverse variance random-effects model and fixed-effects model, respectively. Six studies (n=237) were involved in the analysis. For 12 months follow up, high dose (>0.1 mg) of rhTSH significantly reduced GV (MD=17.61; 95% CI=12.17 to 23.04; p<0.00001) compared with placebo. No effective pooled results of low dose of rhTSH (<0.1 mg) were applicable for only one study included. For 6 months follow up, the source of heterogeneity was determined by subgroup and sensitivity analysis. High dose group showed vast improvement in GV reduction (MD=16.62; 95% CI=1.34 to 31.90; p=0.03). The reduction of low dose group compared with placebo was inferior to high dose group. No available data were obtained to assess the influence of rhTSH after 36 months follow up for the only included study. Hypothyroidism incidence was higher for rhTSH group. No publication bias was seen. High dose of rhTSH treatment-stimulated radioactive 131I therapy after 6 months and 12 months follow up had a better effect in reducing GV, but with higher incidence of hypothyroidism. Owing to the limited methodological quality, more clinical researches are warranted in the future.

Effect of Different Doses of Propofol and Nerve block Combined with General Anesthesia on The Intraoperative Anesthesia and Postoperative Awakening and Cognitive Function in Elderly Patients with Knee Osteoarthritis

2021 ◽  
Vol 7 (4) ◽  
pp. 697-705
Author(s):  
Jianhui Ma ◽  
Meimei Pang ◽  
Xin Ding ◽  
Shirong Fang ◽  
Lichao Chu
Keyword(s):  
Cognitive Function ◽  
Elderly Patients ◽  
General Anesthesia ◽  
Nerve Block ◽  
Dose Group ◽  
Low Dose ◽  
High Dose Group ◽  
High Dose ◽  
Knee Oa ◽  
Different Doses

Objective. To explore the effect of different doses of propofol and nerve block combined with general anesthesia on the intraoperative anesthesia and postoperative awakening and cognitive function in elder patients with knee osteoarthritis (OA). Methods. According to the inclusion criteria for research object, we selected 98 elderly patients with knee OA who needed surgery and were admitted to our hospital from January 2019 to January 2021 for the study. Patients were divided into the low dose group (given 2 mg/kg propofol by pumping under constant speed during surgery) and the high dose group (given 4 mg/kg propofol by pumping during surgery) by the number table method to compare their indicators including the intraoperative anesthesia effect, with 49 cases in each group. Results. No between-group difference was shown in the anesthesia time and postoperative VAS scores, but the awakening time of the low dose group was significantly shorter than that of the high dose group (P<0.05); the differences in heart rate (HR) values at various time points between the two groups were not obvious, but the high dose group obtained significantly higher HR values at T4 than the low dose group; the mean arterial pressure (MAP) values of both groups were significantly reduced at Ti and then returned to the level before anesthesia (P>0.05); the bispectral index scores (BIS) of both groups experienced a marked drop at Ti and then recovered gradually, but failed to return to the level at T0 till the end, and a between-group difference in BIS indexes presented at Ti; the plasma corticosterone (CORT) concentration at Ti of both groups were significantly lowered and then returned to the level at T0, with no between-group difference; and compared with the low dose group, the high dose group achieved slightly lower mini-mental state examination (MMSE) scores at 24-72 h after surgery, with no significant difference between them (P>0.05). Conclusion. The therapy of different doses of propofol and nerve block combined with general anesthesia has no significant effect on the cognitive function in elderly knee OA patients after surgery. With the nerve block improving the analgesic effect, a low dose of propofol is good for the postoperative awakening of patients. Different doses of propofol inhibited the stress response to a different degree and produced good anesthesia outcomes in elderly patients, but comparatively speaking, a low-dose propofol ensures more smooth indexes and less effect on the intraoperative hemodynamics.

scholarly journals Research on the Effects of the Extract of Polygala fallax Hemsl on Sex Hormones and ?-EP in Perimenopausal Rat Models

2020 ◽  
Vol 4 (3) ◽  
Author(s):  
Siyuan Yang ◽  
Zhiyong Cao ◽  
Jiabao Chen ◽  
Gang Fang
Keyword(s):  
Menstrual Cycle ◽  
Sex Hormones ◽  
Dose Group ◽  
Low Dose ◽  
Normal Group ◽  
Dose Effect ◽  
High Dose Group ◽  
High Dose ◽  
Model Group ◽  
Rat Models

Objective: To study the effects of the ethnic medicine Polygala fallax Hemsl with Guangxi characteristics on the sex hormones and ?-EP in research objective perimenopausal rat models. Methods: 40 female SPF rats were randomly divided into 4 groups, including the normal, model, high-dose and low-dose groups. Rats of three groups except for the normal one were treated with perimenopausal modelling through the method of subcutaneous injection of compound 4-VCD for 15 consecutive days. Rats of the normal and model group were normally fed without any treatment. Rats of the high-dose and low-dose groups were administered by high- and low-dose intragastric administration of the extract of Polygala fallax Hemsl. According to the menstrual cycle of the vaginal smear of the rat, each menstrual cycle is a course of treatment and 6 consecutive courses of treatment would be given. The indexes of serum sex hormones (E2, FSH, LH) and ?-EP of rats in each group were observed after treatment. Results: After the treatment of 6 cycles, for the levels of ?-EP and E2, the model group was lowest (P<0.05), the normal group was highest (P<0.05); and the high-dose group was higher than the low-dose group; For the levels of FSH and LH, the normal group was lowest (P<0.05), the model group was highest (P<0.05), and the high-dose group was lower than the low-dose group. Conclusion: Guangxi characteristic national medicine Polygala fallax Hemsl can effectively improve the levels of serum sex hormones and ?-EP in perimenopausal rat models and relieve the related symptoms with a certain dose-effect relationship.

Carcinogenesis Bioassay of Propyl Gallate in F344 Rats and B6C3FJ Mice

1983 ◽  
Vol 2 (6) ◽  
pp. 425-433 ◽  
Author(s):  
K. M. Abdo ◽  
J. E. Huff ◽  
J. K. Haseman ◽  
M. P. Dieter ◽  
G. A. Boorman ◽  
...  
Keyword(s):  
Propyl Gallate ◽  
Dose Group ◽  
Low Dose ◽  
Female Rats ◽  
Male Rats ◽  
High Dose Group ◽  
High Dose ◽  
Preputial Gland ◽  
Rats And Mice ◽  
F344 Rats

Chronic toxicity studies were conducted by maintaining groups of 50 F344 rats and 50 B6C3F1 mice of each sex on nutritionally complete diets containing 0%, 0.6%, or 1.2% propyl gallate for 103 weeks. Survival of rats and mice of both sexes was not significantly affected by the administration of this compound. Dosed rats and mice showed growth retardation and reduced feed utilization efficiency. Increased incidence of hepatic cytoplasmic vacuolization and suppurative inflammation of the prostate gland were observed in dosed male rats and were considered to be related to propyl gallate administration. Tumors of the preputial gland, islet ceil tumors of the pancreas, and pheochromocytoma of the adrenal gland were observed with significantly (p < 0.05) higher incidence in the low-dose male rats; however, there was little evidence of a dose response or of an effect in the high-dose group. Rare tumors (an astrocytoma and a glioma) were found in the brains of two low-dose female rats but none was found in the high-dose group. Malignant lymphoma occurred with a significant (p < 0.05) positive trend in male mice and the incidence in the high-dose group was significantly (p < 0.05) higher than that of the concurrent controls. However, the high-dose incidence was not significantly different from the historical control rate for the laboratory that conducted the bioassay. Under the conditions of the bioassay, propyl gallate was not considered to be clearly carcinogenic for F344 rats, although the increased incidence of preputial gland tumors, islet-cell tumors of the pancreas, and pheochromocytoma of the adrenal glands in low-dose male rats may have been related to compound administration. Thus, the evidence for carcinogenicity in male rats is regarded as being equivocal, while there was no indication of a carcinogenic response in female rats. Propyl gallate was not considered to be carcinogenic for B6C3F1 mice, although the increased incidence of malignant lymphoma in dosed male mice may have been related to administration of the test compound.

Failure of oxygen radical scavengers to modify fatigue in electrically stimulated muscle

1991 ◽  
Vol 69 (10) ◽  
pp. 1470-1475 ◽  
Author(s):  
Ian Shrier ◽  
Sabah Hussain ◽  
Sheldon Magder
Keyword(s):  
Blood Flow ◽  
Dose Group ◽  
Gastrocnemius Muscle ◽  
Low Dose ◽  
Muscle Tension ◽  
Oxygen Radical ◽  
High Dose Group ◽  
High Dose ◽  
Partial Recovery ◽  
Radical Scavengers

We used in situ gastrocnemius muscle of anaesthetized dogs to test the hypothesis that O2 radical production during muscle contraction contributes to fatigue. Muscle tension was measured with a force transducer and blood flow was monitored with an electromagnetic flow probe. Muscle contractions were produced by stimulating the nerve for 15 min at 20 Hz, 12 trains/min, and a duty cycle of 0.25. Three groups of seven animals were given an infusion of 0.2 mL∙min−1 of either saline, low-dose oxygen radical scavengers (250 IU∙mL−1 superoxide dismutase, 640 IU∙mL−1 polyethylene glycol (PEG)-catalase, 0.25 mg∙mL−1 deferoxamine, and 0.1 mg∙mL−1 oxypurinol), or high-dose oxygen radical scavengers (3300 IU∙mL−1 uperoxide dismutase, 6600 IU∙mL−1 PEG-catalase, 2.5 mg∙mL−1 deferoxamine, and 0.1 mg∙mL−1 oxypurinol). Blood flow and vascular resistance of the gastrocnemius muscle during stimulation did not differ among groups. After 15 min of stimulation, the developed tension (represented as a percentage of initial tension developed) was 66 ± 7% in the saline treated group, 70 ± 6% in the low-dose group, and 70 ± 4% in the high-dose group. The change in tension during recovery was not significant in the control or low-dose groups. However, there was partial recovery in the high-dose group. In conclusion, in this preparation, oxygen radical scavengers did not delay the development of decreased muscle tension.Key words: muscle fatigue, oxygen free radicals, resistance, flow.

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