Medizinische Universität Graz Austria/Österreich - Forschungsportal - Medical University of Graz
Gewählte Publikation:
Maier, LS; Bers, DM; Pieske, B.
Differences in Ca(2+)-handling and sarcoplasmic reticulum Ca(2+)-content in isolated rat and rabbit myocardium.
J Mol Cell Cardiol. 2000; 32(12):2249-2258
Doi: 10.1006/jmcc.2000.1252
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- Führende Autor*innen der Med Uni Graz
- Pieske Burkert Mathias
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- Abstract:
- We made novel measurements of the influence of rest intervals and stimulation frequency on twitch contractions and on sarcoplasmic reticulum (SR) Ca(2+)-content (using rapid cooling contractures, RCCs) in isolated ventricular muscle strips from rat and rabbit hearts at a physiological temperature of 37 degrees C. In addition, the frequency-dependent relative contribution of SR Ca(2+)-uptake and Na(+)/Ca(2+)-exchange for cytosolic Ca(2+)-removal was assessed by paired RCCs. With increasing rest intervals (1-240 s) post-rest twitch force and RCC amplitude decreased monotonically in rabbit myocardium (after 240 s by 45+/-10% and 61+/-11%, respectively P<0. 05, n=14). In contrast, rat myocardium (n=11) exhibited a parallel increase in post-rest twitch force (by 67+/-16% at 240 s P<0.05) and RCC amplitude (by 20+/-14%P<0.05). In rabbit myocardium (n=11), increasing stimulation frequency from 0.25 to 3 Hz increased twitch force by 295+/-50% (P<0.05) and RCC amplitude by 305+/-80% (P<0.05). In contrast, in rat myocardium (n=6), twitch force declined by 43+/-7% (P<0.05), while RCC amplitude decreased only insignificantly (by 16+/-7%). The SR Ca(2+)-uptake relative to Na(+)/Ca(2+)-exchange (based on paired RCCs) increased progressively with frequency in rabbit, but not in rat myocardium (;66+/-2% at all frequencies). We conclude that increased SR Ca(2+)-load contributes to the positive force-frequency relationship in rabbits and post-rest potentiation of twitch force in rats. Decreased SR Ca(2+)-load contributes to post-rest decay of twitch force in rabbits, but may play only a minor role in the negative force-frequency relationship in rats. SR Ca(2+)-release channel refractoriness may contribute importantly to the negative force-frequency relationship in rat and recovery from refractoriness may contribute to post-rest potentiation.
- Find related publications in this database (using NLM MeSH Indexing)
- Animals -
- Calcium - metabolism
- Cold - metabolism
- Electrophysiology - metabolism
- Muscle Fibers - physiology
- Myocardial Contraction - physiology
- Myocardium - metabolism
- Rabbits - metabolism
- Rats - metabolism
- Rats, Sprague-Dawley - metabolism
- Sarcoplasmic Reticulum - metabolism
- Temperature - metabolism
- Time Factors - metabolism
- Find related publications in this database (Keywords)
- SR Ca2+-content
- rapid cooling contractures
- force-frequency relationship
- post-rest behavior