caa a22 4500 465826369 CHVBK 20180323112150.0 cr unu---uuuuu 170327e19900401xx s 000 0 eng 10.1007/BF00258770 doi (NATIONALLICENCE)springer-10.1007/BF00258770 Characterization of the calcium paradox in the isolated perfused frog heart: enzymatic, ionic, contractile and electrophysiological studies [Elektronische Daten] [Maria Touraki, Isidoros Beis] Summary: The effect of perfusion temperature and duration of calcium deprivation on the occurrence of the calcium paradox was studied in the isolated frog heart. Loss of electrical and mechanical activity, ion fluxes, creatine kinase and protein release were used to define cell damage. Perfusion was performed at 22, 27, 32, and 37°C, and calcium deprivation lasted 10, 20, 30, or 40 min. At 22°C and 27°C even a prolonged calcium-free perfusion failed to induce a calcium paradox. After 30 min of calcium-free perfusion at 37°C ventricular activity ceased and a major contraction occurred followed by an increase in resting tension. During the 15-min re-perfusion period the release of creatine kinase was 158.24±2.49 IU·g dry wt-1, and the total amount of protein lost was 70.37±0.73 mg·g dry wt−1, while lower perfusion temperatures resulted in a decreased loss of protein and creatine kinase. Ion fluxes in the perfusion effluent indicate that during re-perfusion a massive calcium influx accompanied by a potassium and a magnesium efflux, and an apparent sodium efflux, occur at a perfusion temperature of 37°C after 30 min of calcium deprivation. The results suggest that the basic principles and damaging effects of calcium overloading are common to both mammalian and frog hearts. Springer-Verlag, 1990 Calcium paradox nationallicence Frog heart nationallicence Enzyme release nationallicence Electromechanical uncoupling nationallicence Calcium overload nationallicence Touraki Maria Laboratory of Animal Physiology, School of Sciences, University of Thessaloniki, 54006, Thessaloniki, Greece aut Beis Isidoros Laboratory of Animal Physiology, School of Sciences, University of Thessaloniki, 54006, Thessaloniki, Greece aut Journal of Comparative Physiology B Springer-Verlag 160/1(1990-04-01), 113-118 0174-1578 160:1<113 1990 160 360 https://doi.org/10.1007/BF00258770 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00258770 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Touraki Maria Laboratory of Animal Physiology, School of Sciences, University of Thessaloniki, 54006, Thessaloniki, Greece aut NATIONALLICENCE 700 1- Beis Isidoros Laboratory of Animal Physiology, School of Sciences, University of Thessaloniki, 54006, Thessaloniki, Greece aut NATIONALLICENCE 773 0- Journal of Comparative Physiology B Springer-Verlag 160/1(1990-04-01), 113-118 0174-1578 160:1<113 1990 160 360 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer