Dual effect of polyaromatic hydrocarbons on sarco(endo)plasmic reticulum calcium ATPase (SERCA) activity of a teleost fish (Oncorhynchus mykiss).

Polycyclic aromatic hydrocarbons (PAHs) are embryo- and cardiotoxic to fish that might be associated with improper intracellular Ca management. Since sarco(endo)plasmic reticulum Ca-ATPase (SERCA) is a major regulator of intracellular Ca, the SERCA activity and the contractile properties of rainbow trout (Oncorhynchus mykiss) ventricle were measured in the presence of 3- and 4-cyclic PAHs. In unfractionated ventricular homogenates, acute exposure of SERCA to 0.

Transcript expression of inward rectifier potassium channels of Kir2 subfamily in Arctic marine and freshwater fish species.

Inward rectifier K (Kir2) channels are critical for electrical excitability of cardiac myocytes. Here, we examine expression of Kir2 channels in the heart of three Gadiformes species, polar cod (Boreogadus saida) and navaga (Eleginus nawaga) of the Arctic Ocean and burbot (Lota lota) of the temperate lakes to find out the role of Kir2 channels in cardiac adaptation to cold. Five boreal freshwater species: brown trout (Salmo trutta fario), arctic char (Salvelinus alpinus), roach (Rutilus rutilus), perch (Perca fluviatilis) and pike (Esox lucius), and zebrafish (Danio rerio), were included for comparison.

Cardiac voltage-gated sodium channel expression and electrophysiological characterization of the sodium current in the zebrafish (Danio rerio) ventricle.

Na channel α-subunit composition of the zebrafish heart and electrophysiological properties of Na current (I) of zebrafish ventricular myocytes were examined. Eight Na channel α-subunits were expressed in both atrium and ventricle of the zebrafish heart. Na1.

Effects of seasonal acclimatization on thermal tolerance of inward currents in roach (Rutilus rutilus) cardiac myocytes.

To test the hypothesis of temperature-dependent deterioration of electrical excitability (TDEE) (Vornanen, J Exp Biol 219:1941-1952, 2016), the role of sodium (I ) and calcium (I ) currents in heat tolerance of cardiac excitability was examined in a eurythermic fish, the roach (Rutilus rutilus). Densities of cardiac I and I and their acute heat tolerance were measured in winter-acclimatized (WiR) and summer-acclimatized (SuR) fish maintained in the laboratory at 4 ± 1 and 18 ± 1 °C, respectively. A robust L-type Ca current (I ), but no T-type Ca current, was present in roach atrial and ventricular myocytes.

Species- and chamber-specific responses of 12 kDa FK506-binding protein to temperature in fish heart.

The sarcoplasmic reticulum (SR) Ca(2+) release channel or ryanodine receptor (RyR) of the vertebrate heart is regulated by the FK506-binding proteins, FKBP12 and FKBP12.6. This study examines whether temperature-related changes in the SR function of fish hearts are associated with changes in FKBP12 expression.

Temperature dependence of sarco(endo)plasmic reticulum Ca2+ ATPase expression in fish hearts.

Cardiac function in fish acclimates to long-term temperature shifts by generating compensatory changes in structure and function of sarcoplasmic reticulum (SR) including the sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA2). The current study compares temperature responses of the cardiac SERCA in two fish species, burbot (Lota lota) and crucian carp (Carassius carassius), which differ in regard to thermal tolerance and activity pattern. Burbot are cold stenothermal and cold-active, while crucian carp are eurythermal and cold-dormant.

Expression of SERCA and phospholamban in rainbow trout (Oncorhynchus mykiss) heart: comparison of atrial and ventricular tissue and effects of thermal acclimation.

In the heart of rainbow trout (Oncorhynchus mykiss), the rate of contraction and Ca(2+) uptake into the sarcoplasmic reticulum (SR) are faster in atrial than ventricular muscle, and contraction force relies more on SR Ca(2+) stores after acclimation to cold. This study tested the hypothesis that differences in contractile properties and Ca(2+) regulation between atrial and ventricular muscle, and between warm-(WA) and cold-acclimated (CA) trout hearts, are associated with differences in expression of sarco(endo)plasmic reticulum Ca(2+) ATPase (SERCA) and/or phospholamban (PLN), an inhibitor of the cardiac SERCA. Quantitative PCR (SERCA only) and antibodies raised against SERCA and PLN were used to determine abundances of SERCA2 transcripts and SERCA and PLN proteins, respectively, in atrium and ventricle of trout acclimated to cold (+4°C, CA) and warm (+18°C, WA) temperatures.

Expression of calsequestrin in atrial and ventricular muscle of thermally acclimated rainbow trout.

Calsequestrin (CASQ) is the main Ca(2+) binding protein within the sarcoplasmic reticulum (SR) of the vertebrate heart. The contribution of SR Ca(2+) stores to contractile activation is larger in atrial than ventricular muscle, and in ectothermic fish hearts acclimation to low temperatures increases the use of SR Ca(2+) in excitation-contraction coupling. The hypotheses that chamber-specific and temperature-induced differences in SR function are due to the increased SR CASQ content were tested in rainbow trout (Oncorhynchus mykiss) acclimated at either 4 degrees C (cold acclimation, CA) or 18 degrees C (warm acclimation, WA).