Abstract:
NEW FINDINGS:What is the central question of this study? Rate-pressure product (RPP) is commonly used as an index of cardiac 'effort'. In canine and human hearts (which have a positive force-frequency relationship), RPP is linearly correlated with oxygen consumption and has therefore been widely adopted as a species-independent index of cardiac work. However, given that isolated rodent hearts demonstrate a negative force-frequency relationship, its use in this model requires validation. What is the main finding and its importance? Despite its widespread use, RPP is not correlated with oxygen consumption (or cardiac 'effort') in the Langendorff-perfused isolated rat heart. This lack of correlation was also evident when perfusions included a range of metabolic substrates, insulin or β-adrenoceptor stimulation. Langendorff perfusion of hearts isolated from rats and mice has been used extensively for physiological, pharmacological and biochemical studies. The ability to phenotype these hearts reliably is, therefore, essential. One of the commonly used indices of function is rate-pressure product (RPP); a rather ill-defined index of 'work' or, more correctly, 'effort'. Rate-pressure product, as originally described in dog or human hearts, was shown to be correlated with myocardial oxygen consumption (MV̇O2). Despite its widespread use, the application of this index to rat or mouse hearts (which, unlike the dog or human, have a negative force-frequency relationship) has not been characterized. The aim of this study was to examine the relationship between RPP and MV̇O2 in Langendorff-perfused rat hearts. Paced hearts (300-750 beats min(-1)) were perfused either with Krebs-Henseleit (KH) buffer (11 mm glucose) or with buffer supplemented with metabolic substrates and insulin. The arteriovenous oxygen consumption (MV̇O2) was recorded. Metabolic status was assessed using (31) P magnetic resonance spectroscopy and lactate efflux. Experiments were repeated in the presence of isoprenaline and in unpaced hearts where heart rate was increased by cumulative isoprenaline challenge. In KH buffer-perfused hearts, MV̇O2 increased with increasing heart rate, but given that left ventricular developed pressure decreased with increases in rate, RPP was not correlated with MV̇O2, lactate production or phosphocreatine/ATP ratio. Although the provision of substrates or β-adrenoceptor stimulation changed the shape of the RPP-MV̇O2 relationship, neither intervention resulted in a positive correlation between RPP and oxygen consumption. Rate-pressure product is therefore an unreliable index of oxygen consumption or 'cardiac effort' in the isolated rat heart.
journal_name
Exp Physioljournal_title
Experimental physiologyauthors
Aksentijević D,Lewis HR,Shattock MJdoi
10.1113/EP085380subject
Has Abstractpub_date
2016-02-01 00:00:00pages
282-94issue
2eissn
0958-0670issn
1469-445Xjournal_volume
101pub_type
杂志文章abstract:NEW FINDINGS:What is the topic of this review? Brown fat's role in meal-associated thermogenesis and the related consequences for energy balance regulation with a focus on the gut hormone secretin, which has been identified as the endocrine molecular mediator of meal-associated brown fat thermogenesis. What advances do...
journal_title:Experimental physiology
pub_type: 杂志文章
doi:10.1113/EP087878
更新日期:2020-08-01 00:00:00
abstract::Gastric motility was recorded from ferrets chronically prepared with an antral strain gauge. In fasted animals, antral motility showed cycles of activity and quiescence typical of the migrating motor complex (MMC) with a period of 44.7 +/- 6.1 min (n = 4). Anaesthesia with pentobarbitone sodium (50 mg/kg) disrupted th...
journal_title:Experimental physiology
pub_type: 杂志文章
doi:10.1113/expphysiol.1990.sp003448
更新日期:1990-09-01 00:00:00
abstract:NEW FINDINGS:What is the topic of this review? This article draws evidence from the current literature to support the hypothesis that non-coding RNA-mediated gene regulation takes place in the mitochondria. An emphasis is put on skeletal muscle. What advances does it highlight? This review highlights the potential role...
journal_title:Experimental physiology
pub_type: 杂志文章,评审
doi:10.1113/EP086846
更新日期:2018-08-01 00:00:00
abstract::Contractile properties and fibre type composition of slow-twitch soleus muscles from spontaneously hypertensive rats (SHR) were compared with those from a control normotensive strain (Wistar-Kyoto, WKY). Male rats aged around 100 days were used, and muscle tension was recorded isometrically in vitro. Tetanic tension w...
journal_title:Experimental physiology
pub_type: 杂志文章
doi:10.1113/expphysiol.1994.sp003772
更新日期:1994-05-01 00:00:00
abstract::The effects of the bacterial toxin Escherichia coli STa on electrogenic secretion in proximal, mid and distal rat colon were examined in vitro using the short-circuit current (Isc) as an index of secretion. All areas showed toxin-elevated Isc which was reduced by bumetanide. The proximal colon was the most sensitive (...
journal_title:Experimental physiology
pub_type: 杂志文章
doi:10.1113/expphysiol.1991.sp003561
更新日期:1991-11-01 00:00:00
abstract::Chronic heart failure (CHF) impairs muscle O2 delivery (QO2) and, at a given O2 uptake (VO2), lowers microvascular O2 pressures (PmvO2: determined by the QO2-to-VO2 ratio), which may impair recovery of high-energy phosphates following exercise. Because CHF preferentially decreases QO2 to slow-twitch muscles, we hypoth...
journal_title:Experimental physiology
pub_type: 杂志文章
doi:10.1113/expphysiol.2004.027367
更新日期:2004-07-01 00:00:00
abstract:NEW FINDINGS:What is the central question of this study? Does treatment of obstructive sleep apnoea (OSA) with nocturnal oxygen or continuous positive airway pressure (CPAP) improve hypoxic vascular responses, which are reportedly impaired in OSA? What is the main finding and its importance? Cerebrovascular and cardiov...
journal_title:Experimental physiology
pub_type: 杂志文章
doi:10.1113/EP086845
更新日期:2019-04-01 00:00:00
abstract::The sympathetic neural regulation of the cerebral circulation remains controversial. The purpose of the present study was to determine how exercise modulates the simultaneous responsiveness of the cerebral and brachial circulations to 'endogenous' sympathetic activation (cold pressor test). In nine healthy subjects, h...
journal_title:Experimental physiology
pub_type: 杂志文章
doi:10.1113/expphysiol.2010.054387
更新日期:2010-11-01 00:00:00
abstract::What is the central question of this study? Neurocognitive functions can be enhanced by acute aerobic exercise, which could be associated with changes in serum brain-derived neurotrophic factor (BDNF) concentrations. We aimed to explore acute exercise-induced changes in BDNF concentrations, neuropsychological and neur...
journal_title:Experimental physiology
pub_type: 杂志文章
doi:10.1113/EP085682
更新日期:2016-07-01 00:00:00
abstract::In Helix aspersa, activation of the cerebral giant serotonin neurones (GSNs) evokes a biphasic, excitatory synaptic response in the M neurones of the buccal ganglia. Local application of serotonin to the current-clamped M neurones also evokes fast and slow depolarizing responses. The slow response is thought to be dep...
journal_title:Experimental physiology
pub_type: 杂志文章
doi:10.1113/expphysiol.1992.sp003656
更新日期:1992-11-01 00:00:00
abstract::We measured plasma levels of L-arginine, its analogue NG-monomethyl-L-arginine (L-NMMA), and related amino acids in normal subjects and uraemic patients (n = 31), before and after haemodialysis. Plasma levels of L-arginine were reduced to less than half of normal values in uraemic subjects compared with controls, and ...
journal_title:Experimental physiology
pub_type: 杂志文章
doi:10.1113/expphysiol.1996.sp003950
更新日期:1996-05-01 00:00:00
abstract::One of the most basic computational elements within a circuit is the synapse across which signals are transferred. Here we summarize some experimental strategies that allow the synaptic basis of circuit function to be studied through imaging. The two most promising approaches available currently are pHluorin-based rep...
journal_title:Experimental physiology
pub_type: 杂志文章,评审
doi:10.1113/expphysiol.2009.051953
更新日期:2011-01-01 00:00:00
abstract:NEW FINDINGS:What is the central question of this study? Is there sexual dimorphism in the occurrence of hepatic endoplasmic reticulum stress? What is the main finding and its importance? The transition from prepubertal to the adult age is associated with an increase in the unfolded protein response markers in the live...
journal_title:Experimental physiology
pub_type: 杂志文章
doi:10.1113/EP087518
更新日期:2019-05-01 00:00:00
abstract::Cardiovascular arousal is associated with patterned cortical activity changes. Head-down-tilt bed rest (HDBR) dimishes the baroreflex-mediated cardiac control. The present study tested the hypothesis that HDBR deconditioning would modify the forebrain organization for heart rate (HR) control during baroreflex unloadin...
journal_title:Experimental physiology
pub_type: 杂志文章,随机对照试验
doi:10.1113/expphysiol.2012.065557
更新日期:2012-12-01 00:00:00
abstract:NEW FINDINGS:What is the central question of this study? What are the ultrastructural changes of the caecal mucosa and the status of epithelial cellular apoptosis and oxidative reactions in lactating goats after prolonged feeding with a high-concentrate diet? What is the main finding and its importance? High-concentrat...
journal_title:Experimental physiology
pub_type: 杂志文章
doi:10.1113/expphysiol.2014.083352
更新日期:2015-03-01 00:00:00
abstract:NEW FINDINGS:What is the central question of this study? At near-term gestation, foramen ovale blood flow accounts for a significant proportion of fetal left ventricular output. Can the foramen ovale increase its volume blood flow when right ventricular afterload is increased by main pulmonary artery occlusion? What is...
journal_title:Experimental physiology
pub_type: 杂志文章
doi:10.1113/EP087423
更新日期:2019-02-01 00:00:00
abstract::Intracellular pH (pHi) was measured in left ventricular myocytes from hearts hypertrophied by constriction of the thoracic aorta. There was a continuous relation between an increase in heart-to-body weight ratio and a decrease in pHi (mean +/- S.D., 7.06 +/- 0.18 pH units in control hearts vs. 6.87 +/- 0.17 pH units i...
journal_title:Experimental physiology
pub_type: 杂志文章
doi:10.1113/expphysiol.1997.sp004011
更新日期:1997-01-01 00:00:00
abstract::Improved understanding of the processes involved in infarct healing is required for identification of novel therapeutic targets to limit infarct expansion and consequent long-term ventricular remodelling after myocardial infarction. Infarct healing can be modelled effectively in murine models of coronary artery ligati...
journal_title:Experimental physiology
pub_type: 杂志文章,评审
doi:10.1113/expphysiol.2012.064741
更新日期:2013-03-01 00:00:00
abstract::Power spectral analysis of heart rate variability has often been used to assess cardiac autonomic function; however, the relationship of low-frequency (LF) power of heart rate variability to cardiac sympathetic tone has been unclear. With or without adjustment for high-frequency (HF) power, total power or respiration,...
journal_title:Experimental physiology
pub_type: 杂志文章,评审
doi:10.1113/expphysiol.2010.056259
更新日期:2011-12-01 00:00:00
abstract::Interdigestive intestinal motility, and especially phase III of the migrating myoelectric/motor complex (MMC), is responsible for intestinal clearance and plays an important role in prevention of bacterial overgrowth and translocation in the gut. Yet previous results from gnotobiotic rats have shown that intestinal mi...
journal_title:Experimental physiology
pub_type: 杂志文章
doi:10.1113/expphysiol.2005.031708
更新日期:2006-01-01 00:00:00
abstract::Mammalian cardiomyocytes have limited regenerative capacity, such that cell death can result in a net loss of viable contractile elements and a decrease in cardiac functional reserve, both during normal ageing and after insults to the myocardium leading to heart failure. At least four types of cell death have been des...
journal_title:Experimental physiology
pub_type: 杂志文章,评审
doi:10.1113/eph8802549
更新日期:2003-05-01 00:00:00
abstract::Hypertension caused by chronic infusion of angiotensin II (Ang II) in experimental animals is dependent, in part, on increased activity of the sympathetic nervous system. This chronic sympathoexcitatory response is amplified by a high-salt diet, suggesting an interaction of circulating Ang II and dietary salt on sympa...
journal_title:Experimental physiology
pub_type: 杂志文章
doi:10.1113/expphysiol.2011.060491
更新日期:2012-01-01 00:00:00
abstract::The vascular actions of insulin are complex, because it can stimulate both nitric oxide-mediated dilatation and endothelin (ET)-1-mediated constriction. We examined vasoreactivity to insulin in isolated feed arteries of the gastrocnemius (GFA) and soleus muscles (SFA) of 32-week-old Long-Evans Tokushima Otsuka (LETO) ...
journal_title:Experimental physiology
pub_type: 杂志文章
doi:10.1113/expphysiol.2013.074047
更新日期:2014-01-01 00:00:00
abstract::The effect of resistance training on arterial stiffening is controversial. We tested the hypothesis that resistance training would not alter central arterial compliance. Young healthy men (age, 23 +/- 3.9 (mean +/- s.e.m.) years; n = 28,) were whole-body resistance trained five times a week for 12 weeks, using a rotat...
journal_title:Experimental physiology
pub_type: 临床试验,杂志文章
doi:10.1113/expphysiol.2004.029504
更新日期:2005-07-01 00:00:00
abstract::Vagal activity is thought to influence atrial electrophysiological properties and play a role in the initiation and maintenance of atrial fibrillation (AF). We evaluated the effects of acute vagal stimulation on atrial conduction, refractoriness of atrial and pulmonary veins (PVs) and inducibility of AF. An open-chest...
journal_title:Experimental physiology
pub_type: 杂志文章
doi:10.1113/expphysiol.2010.053280
更新日期:2011-02-01 00:00:00
abstract::Pairs of Ia and II afferent fibres supplying primary and secondary endings lying in the same tenuissimus spindles were prepared in barbiturate anaesthetized cats in order to compare the variability in the rhythm of discharge of the two endings during responses elicited by the contraction of different intrafusal muscle...
journal_title:Experimental physiology
pub_type: 杂志文章
doi:10.1113/expphysiol.1994.sp003801
更新日期:1994-09-01 00:00:00
abstract::Haemorrhagic shock (HS) and fluid resuscitation can lead to increased reactive oxygen species (ROS), contributing to ischaemia-reperfusion injury and organ damage. Ubiquinol is a potent antioxidant that decreases ROS. This study examined the effects of ubiquinol administered with fluid resuscitation following controll...
journal_title:Experimental physiology
pub_type: 杂志文章
doi:10.1113/expphysiol.2014.078600
更新日期:2014-07-01 00:00:00
abstract:NEW FINDINGS:What is the central question of this study? Are the urinary concentrations of NO and ATP, and their metabolites, associated with the severity of symptoms of overactive bladder? What is the main finding and its importance? The urinary ratios of [ATP/NO], [ADP/NO] and a combination of these, [ATP/Cr*ADP/Cr]/...
journal_title:Experimental physiology
pub_type: 杂志文章
doi:10.1113/EP088450
更新日期:2020-06-01 00:00:00
abstract::The study examined the effect of salt-induced hypertension on vascular relaxation in response to magnesium sulphate during pregnancy. Pregnant Wistar rats were fed for 6 weeks on a diet containing 0.3% (control) and 8.0% (test) sodium chloride. Aortic rings were then removed and contracted with 10(-7) M phenylephrine ...
journal_title:Experimental physiology
pub_type: 杂志文章
doi:10.1113/expphysiol.1995.sp003836
更新日期:1995-01-01 00:00:00
abstract::The present study was designed to investigate the renal responses to hypotensive haemorrhage early in life and the role of renal sympathetic nerves in modulating these renal responses. To this end, experiments were carried out in conscious, chronically instrumented lambs with either intact renal nerves (n = 7, Intact)...
journal_title:Experimental physiology
pub_type: 杂志文章
doi:10.1113/eph8702434
更新日期:2002-09-01 00:00:00