Abstract：
:Our purpose was to determine the effect of eight different combinations of contraction intensity, duration, and rest on the rate of fatigue in vastus lateralis muscle. A single combination consisted of contractions at 30 or 70% maximal voluntary contraction (MVC), held for 3 or 7 s with 3- or 7-s rest intervals. Contractions were repeated until the subject could not hold the force for the requisite duration. At regular intervals during each experiment, a brief MVC, a single twitch, and the response to eight stimulation pulses at 50 Hz were elicited. The rate of fatigue was the rate of decline of MVC calculated from regression analysis. Mean rate of fatigue (n = 8) ranged from 0.3 to 25% MVC/min and was closely related (r = 0.98) to the product of the relative force and the duty cycle. Force from 50 Hz stimulation fell linearly and in parallel with MVC. Twitch force was first potentiated and then fell twice as fast as 50 Hz stimulation and MVC (p less than 0.05). Differentiated twitch contraction and relaxation rates were higher at potentiation and lower at the limit of endurance, compared with control values (p less than 0.05). The maximal electromyogram decreased 25% and the submaximal EMG increased to maximal by the end of the protocol, indicating that the entire motor unit pool had been recruited. The close relation between rate of fatigue and the force x time product probably reflects the off-setting interaction of contraction amplitude, duration, and rest interval. This occurs despite the changes in twitch characteristics and the apparent recruitment of fast fatiguing motor units.
journal_name
Can J Physiol Pharmacoljournal_title
Canadian journal of physiology and pharmacologyauthors
Dolmage T,Cafarelli Edoi
10.1139/y91-211subject
Has Abstractpub_date
1991-10-01 00:00:00pages
1410-5issue
10eissn
0008-4212issn
1205-7541journal_volume
69pub_type
杂志文章abstract：:Rhus tripartitum D.C., Anacardiaceae, has traditionally been used in Tunisia against many illnesses. The present study investigates, for the first time, the protective effects of the methanol extract of Rhus tripartitum fruit (MERT) against CCl4-induced hepatotoxicity and cisplatin-induced nephrotoxicty in Wistar rats...
journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章
doi：10.1139/cjpp-2016-0029
更新日期：2016-08-01 00:00:00
abstract：:In vivo fatty acid synthesis and the pathways of glycerol-3-phosphate (G3P) production were investigated in brown adipose tissue (BAT) from rats fed a cafeteria diet for 3 weeks. In spite of BAT activation, the diet promoted an increase in the carcass fatty acid content. Plasma insulin levels were markedly increased i...
journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章
doi：10.1139/y08-052
更新日期：2008-07-01 00:00:00
abstract：:The vasculature of the mammalian renal medulla is complex, having neither discrete input nor output. There is also efficient countercurrent exchange between ascending and descending vasa recta in the vascular bundles. These considerations have hampered measurement of medullary blood flow since they impose pronounced c...
journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章,评审
doi：10.1139/y86-151
更新日期：1986-07-01 00:00:00
abstract：:It has been reported that the intraportal infusion of glutamine in Munich-Wistar rats will cause depression of renal perfusion and the urinary excretion of salt and water. We have attempted to reproduce these findings in anaesthetized dogs. L-Glutamine was infused at doses between 120 and 150 mumol/min into the portal...
journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章
doi：10.1139/y92-201
更新日期：1992-10-01 00:00:00
abstract：:The effects of magnesium (from 1.2 to 7.2 mM) were investigated in isolated perfused rat heart subjected to coronary artery ligation and reperfusion. Increasing magnesium concentrations, of the medium containing 3.00 mM of calcium, induced a significant bradycardia and a protective effect towards reperfusion arrhythmi...
journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章
doi：10.1139/y90-105
更新日期：1990-06-01 00:00:00
abstract：:The effect of 6-hydroxydopamine (6-OH-dopamine) and of a cholesterol rich diet on the plasma and aortic cholesterol of female rats were studied. Both the diet and the 6-OH-dopamine produced an important increase in plasmatic and aortic cholesterol. A synergistic effect of these two treatments was observed on the plasm...
journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章
doi：10.1139/y76-014
更新日期：1976-04-01 00:00:00
abstract：:Intra- and extra-cellular concentrations of calcium were measured in hippocampal neurons of areas CA1 and CA3 during 8 min ischaemia and short-term (up to 60 min) recovery. During an ischaemic insult, [Ca2+]i increased progressively and [Ca2+]e decreased. There were large interneuronal differences, although, in genera...
journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章
doi：10.1139/y92-262
更新日期：1992-01-01 00:00:00
abstract：:The disruption to glucose homeostasis upon glucocorticoid (GC) treatment in adult male rats has not been fully characterized in older rats or in females. Thus, we evaluated the age- and gender-related changes in glucose homeostasis in GC-treated rats. We injected male and female rats at 3 months and 12 months of age w...
journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章
doi：10.1139/cjpp-2014-0259
更新日期：2014-10-01 00:00:00
abstract：:We examined whether there was a threshold for change in fetal arterial PO2 to elicit alterations in plasma adrenocorticotropic hormone, arginine vasopressin, or cortisol, or to affect the incidence of fetal breathing movements or eye movements and we determined whether such a threshold changed with gestational age. Fe...
journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章
doi：10.1139/y90-080
更新日期：1990-05-01 00:00:00
abstract：:Previous reports demonstrated that cilostazol, a phosphodiesterase 3 inhibitor, affected cellular electrophysiology and reduced episodes of ventricular fibrillation (VF) in patients with Brugada syndrome. However, its effects on VF induction and defibrillation efficacy have never been investigated. We tested the hypot...
journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章
doi：10.1139/y09-127
更新日期：2010-04-01 00:00:00
abstract：:The intraperitoneal administration of insulin has been recommended because it was found to effectively control the plasma glucose level. Several authors have suggested that intraperitoneal insulin administration may be more "physiological" and therefore preferable because the insulin is absorbed into the portal venous...
journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章
doi：10.1139/y86-036
更新日期：1986-03-01 00:00:00
abstract：:The endothelium, although only a single layer of cells lining the vascular and lymphatic systems, contributes in multiple ways to vascular homeostasis. Subsequent to the 1980 report by Robert Furchgott and John Zawadzki, there has been a phenomenal increase in our knowledge concerning the signalling molecules and path...
journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章,评审
doi：10.1139/y2012-073
更新日期：2012-06-01 00:00:00
abstract：:Coronary flow was recorded from spontaneously beating isolated perfused hearts of rats and guinea pigs. Arachidonic acid (AA), in single bolus doses, produced a fast short lasting coronary constriction followed by a slow developing but persisting vasodilation. These reactions (biphasic type) were characteristic of the...
journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章
doi：10.1139/y84-211
更新日期：1984-10-01 00:00:00
abstract：:The hemodynamic effects of the combination of clonidine and propranolol were studied in conscious rats with portal hypertension owing to secondary biliary cirrhosis. Pressure and blood flow measurements (radioactive microsphere method) were performed in three groups of eight rats before and after drug administration. ...
journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章
doi：10.1139/y89-219
更新日期：1989-10-01 00:00:00
abstract：:The role of iron-loaded transferrin in xanthine-xanthine oxidase (X-XO) induced cardiac injury in isolated perfused rat hearts was examined. X (2 mM) - XO (10 U/L) perfusion resulted in contractile failure, a rise in resting tension, an increase in lipid peroxidation, and myocardial cell damage. The addition of transf...
journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章
doi：10.1139/y90-068
更新日期：1990-04-01 00:00:00
abstract：:Newborn hearts have restricted functional reserve and variable responsiveness to inotropes that could be partly due to differences in myocardial beta-adrenoceptors (beta-AR). To clarify this issue, this study documented ventricle-specific changes in myocardial beta-AR density and affinity during postnatal maturation. ...
journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章
doi：10.1139/y06-026
更新日期：2006-08-01 00:00:00
abstract：:Infarct-like lesion induced by isoprenaline is a well-known model to study myocardial infarction (MI). Vitamin D has been shown to have anti-inflammatory and antioxidant effects. Recent studies highlighted cross talk between vitamin D and peroxisome proliferator-activated receptor gamma (PPAR-γ). The present study was...
journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章
doi：10.1139/cjpp-2016-0150
更新日期：2017-06-01 00:00:00
abstract：:Effect of Ni2+ on Zn2+-induced potentiation of twitch tension was studied electrophysiologically in the toe muscle fibers of Rana catesbeiana. The major findings of this investigation are as follows. When 2 mM Ni2+ was applied to fibers in a normal Ringer's solution containing 50 microM Zn2+ (Zn2+ solution), the Zn2+-...
journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章
doi：10.1139/y86-104
更新日期：1986-05-01 00:00:00
abstract：:Nonalcoholic fatty liver disease (NAFLD) is a spectrum of chronic liver conditions that are characterized by steatosis, inflammation, fibrosis, and liver injury. The global prevalence of NAFLD is rapidly increasing in proportion to the rising incidence of obesity and type 2 diabetes. Because NAFLD is a multifaceted di...
journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章,评审
doi：10.1139/cjpp-2016-0681
更新日期：2017-10-01 00:00:00
abstract：:Tension responses to ramp shortening of varying speed in whole muscle or single fibres from the plateau of an isometric tetanus, revealed at least two distinct phases. There was a fast initial drop in tension followed by a change of slope and a definite inflexion on the tension record. As the velocity of the imposed l...
journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章
doi：10.1139/y85-268
更新日期：1985-12-01 00:00:00
abstract：:This study developed an animal model of gestational obesity and prediabetes in Sprague Dawley rats using 35% sucrose supplementation (SS). Postprandially, insulin stimulates glucose uptake and nutrient partitioning via insulin-dependent as well as Hepatic Insulin Sensitizing Substance (HISS)-dependent action. HISS is ...
journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章
doi：10.1139/cjpp-2020-0340
更新日期：2020-10-16 00:00:00
abstract：:Isolated rabbit hearts undergo ventricular depolarization when exposed to 0.5 mM K--Krebs during 30 to 45 min. A ventricular tachyarrhythmia develops when these hearts are allowed to repolarize in 1.5 mM K--Krebs. Ventricular fibrillation usually follows. These arrhythmias do not cease spontaneously. Initially, perfus...
journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章
doi：10.1139/y82-226
更新日期：1982-12-01 00:00:00
abstract：:The area postrema (AP) is one of the circumventricular organs of the brain and as such it is highly vascular and lacks the normal blood-brain barrier. Anatomical tracing studies have demonstrated afferent projections to AP originating from the paraventricular nucleus, lateral parabrachial nucleus (l-PBN), nucleus trac...
journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章,评审
doi：10.1139/y91-153
更新日期：1991-07-01 00:00:00
abstract：:The effects of leukotrienes (LTs) have been widely studied in the isolated perfused mammalian heart; however, little is known about the effect or metabolism of LTs in the isolated bullfrog heart. Isolated perfused bullfrog hearts were administered randomized doses of LTC4, LTD4, or LTE4. The cardiac parameters of hear...
journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章
doi：10.1139/y88-161
更新日期：1988-08-01 00:00:00
abstract：:Vanadium (V) as sodium orthovanadate induces an increase in lipid peroxidation in the kidneys after a single subcutaneous or intraperitoneal injection to rats or mice. The rate of malondialdehyde (MDA) formation, an index of lipid peroxidation, by kidney homogenates increased by more than 100% 1 h after injection. Chr...
journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章
doi：10.1139/y85-037
更新日期：1985-03-01 00:00:00
abstract：:The effects of localized distension of the pulmonary vein - left atrial junctions on plasma arginine vasopressin (AVP) have been examined in chloralose anaesthetized dogs. Pulmonary vein distension caused an increase in heart rate and a decrease in plasma AVP concentration. Cooling the vagosympathetic nerves to 10 deg...
journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章
doi：10.1139/y83-136
更新日期：1983-08-01 00:00:00
abstract：:The present experiments were designed to evaluate vascular reactivity to angiotensin II in rats with experimental cirrhosis of the liver (induced with CCl4 and phenobarbital) before ascites appearance. The systemic pressor response to angiotensin II in conscious animals and the contractile effect of angiotensin II in ...
journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章
doi：10.1139/y89-243
更新日期：1989-12-01 00:00:00
abstract：:Using conventional intracellular microelectrode techniques, the membrane potential (Em) of vascular smooth muscle cells in isolated segments of thoracic rat aorta was measured. The influence of exogenous and of endothelium-derived nitric oxide on the Em was assessed, and the involvement of glibenclamide-sensitive chan...
journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章
doi：
更新日期：1997-12-01 00:00:00
abstract：:Both the kidney and colon secrete bicarbonate and transport water and electrolytes. The respective contributions of these two organs to acid-base and electrolyte balance in normal man has thus been studied in eight healthy male volunteers who underwent simultaneous renal clearance studies, and colonic perfusion with a...
journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章
doi：10.1139/y77-003
更新日期：1977-02-01 00:00:00
abstract：:The effects of 5-hydroxytryptamine (5-HT) on spinal motoneurons were examined in pentobarbital-anaesthetized cats and in nonanaesthetized decerebrate cats by intracellular recording and extracellular iontophoresis of 5-HT. 5-HT first induced a depolarization and then a long-lasting hyperpolarization (up to 60 min) wit...
journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章
doi：10.1139/y91-022
更新日期：1991-02-01 00:00:00
