caa a22 4500 605514399 CHVBK 20210128100704.0 cr unu---uuuuu 210128e20151201xx s 000 0 eng 10.1007/s00360-015-0931-7 doi (NATIONALLICENCE)springer-10.1007/s00360-015-0931-7 Temperature-dependence of L-type Ca2+ current in ventricular cardiomyocytes of the Alaska blackfish ( Dallia pectoralis ) [Elektronische Daten] [Kerry Kubly, Jonathan Stecyk] To lend insight into the overwintering strategy of the Alaska blackfish (Dallia pectoralis), we acclimated fish to 15 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 (I Ca). Peak I Ca density at 5°C (−1.1±0.1pApF−1) was 1/8th that at 15°C (−8.8±0.6pApF−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 I Ca was ~4.5 times greater at 5°C than at 15°C, and the voltage for half-maximal inactivation was shifted from −23.3±1.0mV at 15°C to −19.8±1.2mV at 5°C. These modifications increase the open probability of the channel and culminate in an approximate doubling of the L-type Ca2+ window current, which contributes to approximately 15% of the maximal Ca2+ conductance at 5°C. Consequently, the charge density of I Ca (Q Ca) and the total Ca2+ transferred through the L-type Ca2+ channels (Δ[Ca2+]) were not as severely reduced at 5°C as compared to peak I Ca density. In combination, the results suggest that while the Alaska blackfish substantially down-regulates I Ca 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. Springer-Verlag Berlin Heidelberg, 2015 Electrophysiology nationallicence I Ca nationallicence Heart nationallicence Thermal acclimation nationallicence Kubly Kerry Department of Biological Sciences, University of Alaska Anchorage, 3211 Providence Drive, Conoco Philips Integrated Science Building, 99508, Anchorage, AK, USA aut Stecyk Jonathan Department of Biological Sciences, University of Alaska Anchorage, 3211 Providence Drive, Conoco Philips Integrated Science Building, 99508, Anchorage, AK, USA aut Journal of Comparative Physiology B Springer Berlin Heidelberg 185/8(2015-12-01), 845-858 0174-1578 185:8<845 2015 185 360 https://doi.org/10.1007/s00360-015-0931-7 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s00360-015-0931-7 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Kubly Kerry Department of Biological Sciences, University of Alaska Anchorage, 3211 Providence Drive, Conoco Philips Integrated Science Building, 99508, Anchorage, AK, USA aut NATIONALLICENCE 700 1- Stecyk Jonathan Department of Biological Sciences, University of Alaska Anchorage, 3211 Providence Drive, Conoco Philips Integrated Science Building, 99508, Anchorage, AK, USA aut NATIONALLICENCE 773 0- Journal of Comparative Physiology B Springer Berlin Heidelberg 185/8(2015-12-01), 845-858 0174-1578 185:8<845 2015 185 360