ABSTRACT A patch-clamp analysis of L-type Ca2+ current in ventricular myocytes cold- and warm-acclimated rainbow trout (Oncorhynchus mykiss) crucian carp (Carassius carassius) hearts was performed. Trout were acclimated at 4 17°C 24°C for a minimum weeks. Ventricular isolated by enzymatic dissociation using collagenase trypsin. Marked species-specific differences noted density its β -adrenergic regulation. The basal (6.9–7.4 pA pF−1) almost double that (4.2–4.5 myocytes. Maximal β-adrenergic...

Cold-acclimated (CA) phenotype of trout heart was induced by 4-wk acclimation at 4 degrees C and characterized 32.7% increase in relative mass 49.8% ventricular myocyte size compared with warm-acclimated (WA; 18 C) fish (P < 0.001). Effect temperature on transcriptome the rainbow examined using species-specific microarray chips containing 1,380 genes. After wk acclimation, 8.8% (122) genes were differently expressed CA WA hearts, most them (82%) upregulated cold 0.01). Transcripts engaged...

The whole cell patch clamp method was used to measure Ca current through L-type channels in enzymatically isolated ventricular myocytes of crucian carp (Carassius carassius L.) heart. Fish were acclimated 22 degrees C for more than 4 wk, and properties measured at room temperature (21 +/- 1 C). Depolarizing voltage steps from -50 mV evoked rapidly activating currents, which exhibited a bell-shaped dependence with peak amplitude 0 mV. currents suppressed by nifedipine (5 microM), verapamil...

ABSTRACT Atrial and ventricular myocardium perform different tasks in the pumping work of vertebrate heart, which are reflected their contractile properties. Although atrial contraction is assumed to have an important role function fish properties not been directly compared any species. The objective this study was clarify differences heart teleost and, particular, elucidate contribution myofibrillar ATPase intracellular Ca2+ stores characteristics contraction. Experiments were conducted on...

Crucian carp Carassius carassius show great phenotypic plasticity in individual morphology and physiology, strong variation population density different fish communities. Small with shallow bodies large heads are typical overcrowded monospecific communities small ponds, whereas deep‐bodied, found larger, multispecies lakes. especially vulnerable to predation by piscivorous their greater relative body depth has been proposed be an induced defence against size‐limited predation, hence adaptive...

Contractile tension in response to 200-ms voltage-clamp pulses was measured isolated guinea pig ventricular cells conditioned constant Ca load. At 23 degrees C, the tension-voltage relation bell shaped, decaying from a maximum at +20 mV zero +100 mV, but 35 C it sigmoidal, with similar twitch tensions and mV. Tension reduced by ryanodine or caffeine abolished removal of just before test pulse. increased markedly as Na concentration patch pipette ([Na]p) varied between 0 20 mM. Cd (300...

ABSTRACT The temperature dependence of heart rate and isometric contractile properties cardiac tissue was determined in thermally acclimated crucian carp (Carassius carassius L.). Fish were adapted for more than 3 weeks to 5 15°C during both summer winter. At all but the lowest experimental temperatures, (FH), maximal force (Fmax) pumping capacity higher fish winter 5°C. Except fH, similar acclimation effects observed when comparing cold- warm-acclimated seasons. In contrast, kinetics...

The hypothesis of pacemaker level origin thermal compensation in heart rate was tested by recording action potentials (AP) intact sinoatrial tissue and enzymatically isolated cells rainbow trout acclimated at 4 degrees C (cold) 18 (warm). With electrophysiological recordings, the primary located base valve, where a morphologically distinct ring comprising myocytes neural elements found histological examination. Intrinsic beating this higher cold-acclimated (46 +/- 6 APs/min) than...

Electrical activity of the heart is assumed to be one key factors that set thermal tolerance limits for ectothermic vertebrates. Therefore, we hypothesized in acclimation--the duration cardiac action potential and repolarizing K+ currents regulate (APD)--the rapid component delayed rectifier current (I(Kr)) inward (I(K1)) are more plastic eurythermal than stenothermal fish species. The hypothesis was tested six freshwater teleosts representing four different orders (Cadiformes,...

Summary The upper thermal tolerance and mechanisms of heat-induced cardiac failure in the brown trout (Salmo trutta fario) was examined. point above which ion channel function sinoatrial contractility vitro, electrocardiogram (ECG) vivo, started to fail (break temperature, BPT) determined by acute temperature increases. In general, electrical excitation heart most sensitive heat intact animal least isolated myocytes (ion currents). BPTs Ca2+ K+ currents were much higher (&amp;gt;28°C) than...

At critically high temperature, cardiac output in fish collapses as a result of depression heart rate (bradycardia). However, the cause bradycardia remains unresolved. To investigate this, rainbow trout (Oncorhynchus mykiss; acclimated at 12°C) were exposed to acute warming while electrocardiograms recorded. From 12°C 25.3°C, electrical excitation between different parts was coordinated, but above atrial and ventricular beating rates became partly dissociated because 2:1 atrioventricular...

Temperature has a strong influence on the excitability and contractility of ectothermic heart that can be alleviated in some species by temperature acclimation. The molecular mechanisms involved temperature-induced improvement cardiac are, however, still poorly known. present study examines role sarcolemmal K + currents from rainbow trout ( Oncorhynchus mykiss) myocytes after thermal two major conductances were identified as Ba 2+ -sensitive background inward rectifier current I K1 )...

This study was designed to compare the activities of sarcoplasmic (SR) Ca2+-ATPase and Ca2+ uptake in fish mammalian hearts determine whether thermal acclimation has any effect on function cardiac SR fish. To this end, we measured thapsigargin-sensitive activity thapsigargin-inhibitable velocity crude homogenates newborn adult rats two teleost (crucian carp rainbow trout) acclimated low (4 degrees C) high (17 C 24 for trout carp, respectively) ambient temperatures. The TG-sensitive highest...

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous contaminants in aqueous environments. They affect cardiovascular development and function fishes. The 3-ring PAH phenanthrene has recently been shown to impair cardiac excitation-contraction coupling by inhibiting Ca2+ K+ currents marine warm-water scombrid To see if similar events take place a boreal freshwater fish, we studied whether the PAHs retene (an alkylated phenanthrene) modify action potential (AP) via effects on Na+ (INa ),...

ABSTRACT Rainbow trout, Oncorhynchus mykiss, inhabit eurythermal environments and must therefore be able to cope with changes in environmental temperature. As ectotherms, their heart is required maintain cardiac function over a range of ambient water temperatures. This raises important questions concerning the temperature-dependence ion channel fish hearts, particular, channels involved Ca2+ transport. Thus, we studied effects acute, physiologically relevant temperature on density kinetics...

ABSTRACT Influx of extracellular Ca2+ plays a major role in the activation contraction fish cardiac cells. The relative contributions Na+/Ca2+ exchange and L-type channels to influx are, however, unknown. Using physiological action potential as command pulse voltage-clamped heart cells, we examined sarcolemmal through crucian carp (Carassius carassius L.) ventricular myocytes. When other cation conductances were blocked, Ni2+-sensitive current with characteristic voltage- time-dependent...