Abstract:
:Energy-deprivation contractures were investigated in unloaded rat ventricular myocytes. Application of 2 mM cyanide in the presence of 10 mM 2-deoxyglucose (metabolic blockade) led to a rapid shortening "contracture" (maximum speed 1.5 +/- 0.2% control cell length/s). Cells shortened to a constant length of 69 +/- 1.6% of the control length. Removal of cyanide caused cells to shorten further ("recontracture"), before relaxing towards the control length. Cells shortened to 57 +/- 2.0% during the recontracture. Similar behaviour was observed in zero extracellular [Ca2+]. Cells permeabilized with saponin (0.1% w/v) responded to the removal of ATP from the bathing solution, and to readdition of ATP, as intact cells did to complete metabolic blockade and its removal. In these permeabilized cells, the extent and speed of contracture shortening were similar at pCa = 7 and pCa greater than 9. When the bath concentration of ATP ([ ATP]b) was lowered to zero, shortening stopped at about 70% of the control length. However, when [ATP]b was lowered to an intermediate level (4-20 microM), cells contracted to lengths as short as 30% of the control length. Similarly, when [ATP]b was restored from zero to an intermediate concentration (4-20 microM), recontracture shortening continued without relaxation. The peak speed of this Ca2(+)-independent shortening showed a sigmoidal dependence on pMgATP (pMgATP0.5 = 4.0). Phosphocreatine (10 mM) shifted the ATP dependence of Ca2(+)-independent shortening to lower [ATP]b (pMgATP0.5 = 5.0), suggesting that gradients of [ATP] could exist between the bath and the myofilaments. Ca2(+)-independent shortening was inhibited by the chemical phosphatase 2,3-butanedione monoxime (BDM), although BDM did not relax cells from the shortened state during energy deprivation. Using a simple model, we show that the results can be explained by cross-bridge cycling occurring independently of Ca2+ over a "window" range of [MgATP] (0.1-100 microM). Therefore, when [MgATP] falls, cross-bridge cycling occurs and the cell shortens. As [MgATP] falls to very low levels ([ MgATP] less than 1 microM), shortening ceases as the rate of cross-bridge cycling declines. Recontracture occurs on restoring ATP production, because stiffness falls and Ca2(+)-independent cross-bridge cycling initially increases. As [MgATP] rises above 100 microM, Ca2(+)-independent cross-bridge cycling ceases and the cell relaxes towards the control length. We conclude that energy-deprivation contractures, and recontractures, can result from changes in [MgATP] and do not necessarily require changes in [Ca2+]i.
journal_name
Can J Physiol Pharmacoljournal_title
Canadian journal of physiology and pharmacologyauthors
Nichols CG,Lederer WJdoi
10.1139/y90-029subject
Has Abstractpub_date
1990-02-01 00:00:00pages
183-94issue
2eissn
0008-4212issn
1205-7541journal_volume
68pub_type
杂志文章abstract::The most important reason for the non-approval and withdrawal of drugs by the Food and Drug Administration is hepatotoxicity. Therefore, this study was undertaken to evaluate the protective effects of hesperidin against cyclophosphamide (CYP)-induced hepatotoxicity in Wistar rats. The rats received a single intraperit...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/cjpp-2014-0204
更新日期:2014-09-01 00:00:00
abstract::The activity of the lipolytic system of the obese hyperglycemic mouse was assessed after treatment with physiological doses of thyroxin (T4). The treatment significantly increased fatty acid mobilization in response to adrenaline over the levels observed in the control mice under all conditions studied. The activities...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/y77-177
更新日期:1977-12-01 00:00:00
abstract::In 2-kidney, 1-clip hypertensive rats, the time course of changes in blood pressure (BP), heart rate, activity of the sympathetic nervous system and the renin-angiotensin system, plasma and blood volumes, left ventricular (LV) and right ventricular (RV) weight, and LV dimensions were evaluated during treatment with hy...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/y86-257
更新日期:1986-12-01 00:00:00
abstract::Salvianolic acid B (Sal B) exerts strong antioxidant activity and eliminates the free radical effect. However, how it affects the antioxidant pathway is not very clear. The objective of this study was to investigate the underlying mechanism of Sal B in CCl4-induced acute liver injury, especially its effect on the Nrf2...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/cjpp-2019-0349
更新日期:2020-03-01 00:00:00
abstract::Biochemical studies using highly condensed Xenopus sperm chromatin and protein extracts prepared from multiple systems have lead to the identification of conserved proteins involved in chromosome decondensation. However, mutations to these proteins are unavailable as the systems used are not amenable to genetic studie...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/y05-042
更新日期:2006-03-01 00:00:00
abstract::Local microinjections of harmaline evoked sustained rhythmic activity in the inferior olive of decerebrate cats. Harmaline appears to exert its action within restricted areas of the inferior olivary complex: the caudal halves of the dorsal and medial accessory nuclei. Since the highly synchronized activity generated b...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/y75-116
更新日期:1975-10-01 00:00:00
abstract::A survey of 'steady-state' serum levels of anticonvulsant drugs from 221 epileptic patients at a university hospital was conducted. Serum concentrations of phenobarbital, primidone, and diphenylhydantoin were determined by a gas chromatographic method. Sixty-five percent (130) of the patients receiving diphenylhydanto...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/y76-119
更新日期:1976-12-01 00:00:00
abstract::Hydroxytyrosol (HT), a phenolic compound in olive oil, exerts an anti-inflammatory effect in cardiovascular diseases. Recent studies found that autophagy was a therapeutic target of diseases. However, the effect of HT on autophagy in vascular adventitial fibroblasts (VAFs) remains unknown. Thus, in this study, we aime...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/cjpp-2016-0676
更新日期:2018-01-01 00:00:00
abstract::The potential of nickel chloride to prevent streptozotocin-induced hyperglycemia was tested in rats in vivo. To induce diabetes, streptozotocin (100 mg/kg body weight) was injected as a single dose. Streptozotocin treatment resulted in a significant decrease in plasma insulin and ceruloplasmin, and pancreatic Cu, prot...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/y88-104
更新日期:1988-05-01 00:00:00
abstract::Slow alpha2-globulin (salpha2G), a high molecular weight glycoprotein, appears as a component of rat serum in a wide variety of both physiologic and pathologic conditions, including pregnancy; it is also present in the neonate. In the present study, the protein was detectable in serum after 6 to 10 days, and was prese...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/y77-071
更新日期:1977-06-01 00:00:00
abstract::Between 1 and 7 days of life, the newborn rabbit heart shifts from predominantly using carbohydrates to predominantly using fatty acids as an energy substrate. We therefore used isolated working hearts from 1- or 7-day-old rabbits to determine the effects of fatty acids on myocardial glucose use and the ability of hea...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/y92-184
更新日期:1992-10-01 00:00:00
abstract::Spironolactone at 10 mg per kilogram per day was given to control and 'one-kidney-one-clip' hypertensive dogs for 6--7 weeks. Compared with untreated animals the treated animals had a lower arterial water content, a higher arterial, myocardial, and skeletal muscle sodium content, and variable changes in tissue potassi...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/y79-096
更新日期:1979-06-01 00:00:00
abstract::The release of endothelium-derived relaxing factor (EDRF), prostacyclin (PGI2), and endothelin-1 (ET-1) was measured from endothelial cells (EC) cultured from either bovine vena cava (BVCEC) or bovine aorta (BAEC). EDRF release was determined by using the superfusion bioassay technique, whereas ET-1 and PGI2 were meas...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/y92-088
更新日期:1992-05-01 00:00:00
abstract::After myocardial infarction, the hemodynamics under basal conditions might appear to be unaltered, which makes it difficult to identify cardiac dysfunction by the usual approaches. Thus, we tested the response to sudden afterload stress in infarcted rats with apparently normal ejection function. Control (CT) and infar...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/y10-062
更新日期:2010-07-01 00:00:00
abstract::The LA/N-corpulent (LA/N-cp) rat is a normotensive strain derived from Koltesky's original mutant strain of the spontaneously hypertensive rat (SHR). When homozygous for the cp gene (cp/cp), the rats are hyperphagous, hyperlipidemic, hyperinsulinemic, and obese. The rats have been shown, by scanning electron microscop...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/y86-215
更新日期:1986-10-01 00:00:00
abstract::Epinephrine caused hyperglycemia in part by increasing gluconeogenesis. However, the mechanism of its gluconeogenic effects has not been studied in ruminants. This study was undertaken to examine the effect of epinephrine on the net hepatic uptake of selected glucose precursors in sheep. The major abdominal blood vess...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/y91-071
更新日期:1991-04-01 00:00:00
abstract::The turnover rate of glucose, the irreversible disposal rate of lactate, and the rate of gluconeogenesis from lactate were calculated by tracer methods in four normal and four alloxan-diabetic dogs under control conditions as well as in chronic, stable metabolic acidosis and alkalosis. Acidosis was produced by feeding...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/y88-025
更新日期:1988-02-01 00:00:00
abstract::As an activator of AMPK, the effect of AICAR on insulin signaling has not been investigated extensively. PI3K-Akt is a critical node involved in the insulin signaling pathway. We observed that concomitant with the activation of AMPK by AICAR, the protein level of PI3K p85α and the insulin-induced phosphorylation of Ak...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/cjpp-2015-0159
更新日期:2016-02-01 00:00:00
abstract::This study aimed to investigate the antiulcer and antioxidant activities of myrtle berry seed aqueous extract (MBSAE) in a peptic ulcer model induced by ethanol in male Wistar rats. MBSAE is rich in total polyphenols, total flavonoids, and unsaturated fatty acids, particularly linoleic (18:2) and oleic (18:1) acids. M...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/cjpp-2016-0094
更新日期:2017-05-01 00:00:00
abstract::Inhibition of prostaglandin synthesis together with vagally mediated peristaltic contractions are essential if mucosal injury is to occur in the stomach of indomethacin-treated rats. The neomycin group of antibiotics has been shown to interfere with acetylcholine release. Agents blocking peristalsis have been demonstr...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/y89-162
更新日期:1989-09-01 00:00:00
abstract::We characterized the innervation of isolated circular and longitudinal-oriented muscle strips from the nulliparous rabbit uterus and cervix by field stimulation (FS). FS with increasing frequency (2.5-50 pps) and voltage (2.5-70 V) caused graded increases in isometric contraction with no relaxation or inhibition of sp...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/y89-131
更新日期:1989-08-01 00:00:00
abstract::This paper provides a brief overview of the adaptive control of prehension. Several primary issues for research in the field are considered. One pertains to the stages of prehensile activity, with particular concern for the kinematic control of precontact phases, and the coordination of load and grip forces following ...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章,评审
doi:10.1139/y94-074
更新日期:1994-05-01 00:00:00
abstract::Opioid and N-methyl-d-aspartate (NMDA) receptors mediate different effects of fluoxetine. We investigated whether opioid and NMDA receptors are involved in the protective effect of fluoxetine against the behavioral despair induced by acute physical stress in male mice. We used the forced swimming test (FST), tail susp...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/cjpp-2015-0429
更新日期:2016-06-01 00:00:00
abstract::This study aimed to investigate the anti-depressant effect of hesperidin (Hsp) in streptozotocin (STZ)-induced diabetic rats. Additionally, the effect of Hsp on hyperglycaemia, oxidative stress, inflammation, brain-derived neurotrophic factor (BDNF), and brain monoamines in diabetic rats was also assessed. The Wistar ...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/cjpp-2014-0281
更新日期:2014-11-01 00:00:00
abstract::Geraniol, a plant-derived monoterpene, has been extensively studied and showed a wide variety of beneficial effects. The aim of this study was to investigate the therapeutic effect of geraniol on functional recovery and neuropathic pain in rats with spinal cord injury (SCI). Rats received a clip-compression SCI and we...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/cjpp-2016-0528
更新日期:2017-12-01 00:00:00
abstract::In Sprague-Dawley rats, we attempted to develop an experimental model to stimulate the cardiac sympathetic nerve. After transverse thoracotomy under anesthesia, a miniature, bipolar electrode was placed on the right ansa subclavia and it was stimulated electrically. The nerve stimulation at 2, 4, and 8.3 Hz (2 ms in d...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:
更新日期:1997-02-01 00:00:00
abstract::Single-electrode voltage-clamp experiments were made on CA1 neurons in the presence of tetrodotoxin and K channel blockers. Applications of halothane (1-3% v/v) for 3-10 min caused a similar marked and reversible depression of slow inward currents (probably Ca currents) evoked by depolarizing pulses from a holding pot...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/y88-257
更新日期:1988-12-01 00:00:00
abstract::Because the excessive apoptosis of articular chondrocytes contributes to extracellular matrix (ECM) loss and cartilage damage in rheumatoid arthritis (RA), inhibiting chondrocyte apoptosis might be a promising strategy for RA. Aquaporin1 (AQP1) is overexpressed in RA cartilage and synovial tissues, and play a vital pa...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/cjpp-2018-0334
更新日期:2018-11-01 00:00:00
abstract::Traumatic brain injury (TBI) is one of the main causes of intellectual and cognitive disabilities. In the clinic it is essential to limit the development of cognitive impairment after TBI. In this study, the effects of gallic acid (GA; 100 mg/kg, per oral, from 7 days before to 2 days after TBI induction) on neurologi...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/cjpp-2014-0546
更新日期:2015-08-01 00:00:00
abstract::Most physiological and pathophysiological responses to bradykinin are mediated by G-protein-coupled receptors designated B2 receptors. Discovery of antagonists for these receptors has brought about a revolution in research in the kinin field. The chemistry and development of antagonists for B2 kinin receptors are disc...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章,评审
doi:10.1139/y95-106
更新日期:1995-07-01 00:00:00