Abstract
We made novel measurements of the influence of rest intervals and stimulation frequency on twitch contractions and on sarcoplasmic reticulum (SR) Ca2--content (using rapid cooling contractures, RCCs) in isolated ventricular muscle strips from rat and rabbit hearts at a physiological temperature of 37 °C. In addition, the frequency-dependent relative contribution of SR Ca2+-uptake and Na+/Ca2+-exchange for cytosolic Ca2+-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 Ca2+-uptake relative to Na+/Ca2+-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 Ca2+-load contributes to the positive force-frequency relationship in rabbits and post-rest potentiation of twitch force in rats. Decreased SR Ca2+-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 Ca2+-release channel refractoriness may contribute importantly to the negative force-frequency relationship in rat and recovery from refractoriness may contribute to post-rest potentiation.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 2249-2258 |
| Number of pages | 10 |
| Journal | Journal of Molecular and Cellular Cardiology |
| Volume | 32 |
| Issue number | 12 |
| DOIs | |
| State | Published - 2000 |
| Externally published | Yes |
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Keywords
- Force-frequency relationship
- Post-rest behavior
- Rapid cooling contractures
- SR Ca-content
ASJC Scopus subject areas
- Molecular Biology
- Cardiology and Cardiovascular Medicine
Cite this
Differences in Ca2+-handling and sarcoplasmic reticulum Ca2+-content in isolated rat and rabbit myocardium. / Maier, Lars S.; Bers, Donald M; Pieske, Burkert.
In: Journal of Molecular and Cellular Cardiology, Vol. 32, No. 12, 2000, p. 2249-2258.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Differences in Ca2+-handling and sarcoplasmic reticulum Ca2+-content in isolated rat and rabbit myocardium
AU - Maier, Lars S.
AU - Bers, Donald M
AU - Pieske, Burkert
PY - 2000
Y1 - 2000
N2 - We made novel measurements of the influence of rest intervals and stimulation frequency on twitch contractions and on sarcoplasmic reticulum (SR) Ca2--content (using rapid cooling contractures, RCCs) in isolated ventricular muscle strips from rat and rabbit hearts at a physiological temperature of 37 °C. In addition, the frequency-dependent relative contribution of SR Ca2+-uptake and Na+/Ca2+-exchange for cytosolic Ca2+-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 Ca2+-uptake relative to Na+/Ca2+-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 Ca2+-load contributes to the positive force-frequency relationship in rabbits and post-rest potentiation of twitch force in rats. Decreased SR Ca2+-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 Ca2+-release channel refractoriness may contribute importantly to the negative force-frequency relationship in rat and recovery from refractoriness may contribute to post-rest potentiation.
AB - We made novel measurements of the influence of rest intervals and stimulation frequency on twitch contractions and on sarcoplasmic reticulum (SR) Ca2--content (using rapid cooling contractures, RCCs) in isolated ventricular muscle strips from rat and rabbit hearts at a physiological temperature of 37 °C. In addition, the frequency-dependent relative contribution of SR Ca2+-uptake and Na+/Ca2+-exchange for cytosolic Ca2+-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 Ca2+-uptake relative to Na+/Ca2+-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 Ca2+-load contributes to the positive force-frequency relationship in rabbits and post-rest potentiation of twitch force in rats. Decreased SR Ca2+-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 Ca2+-release channel refractoriness may contribute importantly to the negative force-frequency relationship in rat and recovery from refractoriness may contribute to post-rest potentiation.
KW - Force-frequency relationship
KW - Post-rest behavior
KW - Rapid cooling contractures
KW - SR Ca-content
UR - http://www.scopus.com/inward/record.url?scp=0034502322&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0034502322&partnerID=8YFLogxK
U2 - 10.1006/jmcc.2000.1252
DO - 10.1006/jmcc.2000.1252
M3 - Article
C2 - 11113000
AN - SCOPUS:0034502322
VL - 32
SP - 2249
EP - 2258
JO - Journal of Molecular and Cellular Cardiology
JF - Journal of Molecular and Cellular Cardiology
SN - 0022-2828
IS - 12
ER -