Sarcoplasmic reticulum, potassium, and cardiac force in rainbow trout and plaice
| Autor: | M. F. el-Sayed, Hans Gesser |
|---|---|
| Rok vydání: | 1989 |
| Předmět: |
medicine.medical_specialty
Trout Physiology chemistry.chemical_element Flounder Calcium chemistry.chemical_compound Caffeine Physiology (medical) Internal medicine medicine Extracellular Animals biology Ryanodine Ryanodine receptor Myocardium Endoplasmic reticulum Heart musculoskeletal system biology.organism_classification Myocardial Contraction Electric Stimulation Sarcoplasmic Reticulum Endocrinology chemistry Flatfishes Potassium Rainbow trout medicine.symptom Extracellular Space Salmonidae Muscle contraction |
| Zdroj: | American Journal of Physiology-Regulatory, Integrative and Comparative Physiology. 257:R599-R604 |
| ISSN: | 1522-1490 0363-6119 |
| Popis: | The role played by the sarcoplasmic reticulum in force development and in cellular Ca2+ balance and its dependence on extracellular K+ were examined in heart ventricular tissue of rainbow trout and plaice. Compared with the steady-state twitch at a stimulation rate of 0.2 Hz, a 30-s rest led to a similar increase in twitch force in trout heart, regardless of whether [K+] was 2.5 or 5 mM. At 5 mM (but not at 2.5 mM) post-rest potentiation increased with increasing rest periods (from 30 to 900 s). These post-rest potentiations were removed or transformed into a loss of force by 10 microM ryanodine or 8 mM caffeine. In the plaice heart, where the sarcoplasmic reticulum is claimed to be sparse, the post-rest potentiation and the influence of ryanodine were small. The Ca2+ uptake measured during 5 min with 45Ca in the trout heart was higher in 5 than in 2.5 mM K+, regardless of the concomitant stimulation rate. This effect of K+ was removed by 10 microM ryanodine. The twitch force after 5 min of rest correlated significantly with the Ca2+ uptake, whereas the twitch force developed at a rate of 0.2 or 1.0 Hz did not. In conclusion, an elevation of K+ appears to stimulate the Ca2+ uptake of the sarcoplasmic reticulum. The twitch force after prolonged rest seems to relate to the Ca2+ contained in this organelle, whereas this does not apply to the twitch force developed at more physiological rates (0.2 or 1 Hz). |
| Databáze: | OpenAIRE |
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