Differences in Ca2+-management between the ventricle of two species of neotropical teleosts: the jeju, Hoplerythrinus unitaeniatus (Spix &amp; Agassiz, 1829), and the acara, Geophagus brasiliensis (Quoy &amp; Gaimard, 1824)

Costa, Monica Jones; Rantin, Francisco Tadeu; Kalinin, Ana Lúcia

doi:10.1590/s1679-62252009000300015

Cited by 1 publication

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“…A number of in vivo and in vitro studies have examined the effects of temperature and oxygen deprivation on the cardiovascular status and cardiac physiology of air-breathing fishes (Costa et al 2005; Costa et al 2009; Iversen et al 2013; McKenzie et al 2007), but none have investigated cardiac excitation-contraction coupling at the level of the isolated cardiomyocyte. Our measurements of cardiomyocyte morphology revealed that ventricular cardiomyocytes of Alaska blackfish are long and thin, much like those of other non-mammalian species (Galli et al 2006; Galli et al 2009; Vornanen et al 2002).…”

Section: Discussionmentioning

confidence: 99%

Temperature-dependence of L-type Ca2+ current in ventricular cardiomyocytes of the Alaska blackfish (Dallia pectoralis)

Kubly

Stecyk

2015

J Comp Physiol B

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Summary To lend insight into the overwintering strategy of the Alaska blackfish (Dallia pectoralis), we acclimated fish to 15°C or 5°C and then utilized whole-cell patch-clamp to characterize the effects of thermal acclimation and acute temperature change on the density and kinetics of ventricular L-type Ca2+ current (ICa). Peak ICa density at 5°C (−1.1± 0.1 pA pF−1) was 1/8th that at 15°C (−8.8 ± 0.6 pA pF−1). However, alterations of the Ca2+- and voltage-dependent inactivation properties of L-type Ca2+ channels partially compensated against the decrease. The time constant tau (τ) for the kinetics of inactivation of ICa was ~4.5-times greater at 5°C than at 15°C, and the voltage for half-maximal inactivation was shifted from −23.3 ± 1.0 mV at 15°C to - 19.8 ± 1.2 mV at 5°C. These modifications increase the open probability of the channel and culminated in an approximate doubling of the L-type Ca2+ window current, which contributed to approximately 15% of the maximal Ca2+ conductance at 5°C. Consequently, the charge density of ICa (QCa) and the total Ca2+ transferred through the L-type Ca channels (Δ[Ca2+]) were not as severely reduced at 5°C as compared to peak ICa density. In combination, the results suggest that while the Alaska blackfish substantially down-regulates ICa with acclimation to low temperature, there is sufficient compensation in the kinetics of the L-type Ca2+ channel to support the level of cardiac performance required for the fish to remain active throughout the winter.

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