Ca uptake by heart cells: I. Ca uptake by the sarcoplasmic reticulum of intact heart cells in suspension
| Autor: | David Redon, Katherine T. Potter, A B Goknur, Angela V. Biggs, Robert A. Haworth |
|---|---|
| Rok vydání: | 1998 |
| Předmět: |
medicine.medical_specialty
Thapsigargin Cardiotonic Agents Physiology Action Potentials Stimulation Heart cells Mitochondria Heart chemistry.chemical_compound Suspensions Internal medicine Caffeine medicine Animals Ca uptake Molecular Biology Cell Size Ion Transport Endoplasmic reticulum Myocardium Isoproterenol Heart Cell Biology Calcium Channel Blockers Myocardial Contraction Electric Stimulation Cell Compartmentation Rats Sarcoplasmic Reticulum Endocrinology chemistry Verapamil cardiovascular system Calcium Central Nervous System Stimulants Female Efflux Calcium Channels medicine.drug |
| Zdroj: | Cell calcium. 23(4) |
| ISSN: | 0143-4160 |
| Popis: | Electric field stimulation of adult rat heart cells suspended in medium with 0.2 mM Ca and isoproterenol caused 45 Ca uptake at a rate (5.25 pmol/mg/beat) proportional to stimulation frequency. Uptake was strongly inhibited by verapamil or thapsigargin. 45 Ca autoradiography showed that stimulation dependent verapamil sensitive uptake was associated with the rod shaped cells, while the uptake by round cells was unaffected by stimulation and was verapamilinsensitive. 45 Ca efflux measurements revealed a caffeine-sensitive component of uptake which was abolished by thapsigargin, and a caffeine-insensitive component. Part of the latter was sensitive to thapsigargin but not to 30 s of stimulation; another part was sensitive to such stimulation but not to thapsigargin. With longer times of stimulation, the caffeine-insensitive pool increased in size, part of which appeared to be mitochondrial Ca uptake via a thapsigarginsensitive pool. The caffeine-sensitive pool labelled quickly in stimulated cells and its size and rate of labelling was increased by stimulation frequency (3.87 pmol/mg/beat), while the caffeine-insensitive pool labelled more slowly and was relatively insensitive to stimulation (0.77 pmol/mg/beat). We conclude that essentially all of the SR Ca pool, as defined by its involvement in excitation-contraction coupling, is released by caffeine. |
| Databáze: | OpenAIRE |
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