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Supernormal excitability in the Luo-Rudy I model of the mammalian ventricular cell

100%

Cieniawa J., Gawda H.

Cellular and Molecular Biology Letters

2002

tom 07

nr Suppl.

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Myocardial calcium compartmentation and contractile control

75%

Langer G. A.

Journal of Physiology and Pharmacology

1991

tom 42

nr 1

Under the condition of rapid perfusion, the time course of contractile response of single ventricular cells to extracellular calcium (Ca) depletion and repletion identifies „fast” and „slow” cellular Ca pools. ⁴⁵Ca exchange was studied in these cells under the same conditions of on-line rapid perfusion. Four kinetically-defined compartments were distinguished: (1) A „rapid” compartment containing 2.6mmoles Ca/kg dry wt of lanthanum (La) displaceable Ca, t½ < 1 sec.; (2) An „intermediate” compartments) containing 2.1 mmoles, t½ = 3 and 19 sec. Caffeine displaced significant amounts of Ca from this compartment whereas La displaced none; (3) A „slow” compartment containing 1.6 mmoles, t½ = 3.6 min. Addition of inorganic phosphate to the perfusate adds significant amounts of Ca to this compartment; (4) An „inexchangeable” compartment, containing 1.2 mmoles. The „rapid” compartment’s flux is > 300 µmoles Ca/kg wet wt/sec. Its exchange rate indicates that it is the kinetic counterpart of the functionally-defined „fast” pool. Its subcellular locus is undefined. The „intermediate” compartment is best correlated with the „slow” pool and represents Ca in the sarcoplasmic reticulum. The „slow” compartment contains a significant fraction from the mitochondria. The results indicate that > 40% of cellular Ca can turn over within the period of one contraction cycle. These results are consistent with the following sequence: (1) Upon sarcolemmal depolarization, Ca moves through the Ca channel to arrive at the SR and at the myofilaments. (2) Ca induced Ca release occurs via the „feet” at the SR-inner SL region. The Ca diffuses to the myofilaments or is transported across the SL via the Na-Ca exchanger. (3) Ca is pumped into the free or longitudinal SR and diffuses to the cistemae. Ca is pumped across the SL by the SL Ca pump and by the Na-Ca exchanger. (4) Mitochondrial Ca exchange via the Na-Ca exchanger and/or SL Ca pump. (Supported by NHLBI and the Laubisch and Castera Endowments.)

Ograniczanie wyników

1 Cellular and Molecular Biology Letters

1 Journal of Physiology and Pharmacology

1 Cieniawa J.

1 Gawda H.

1 Langer G. A.

1 2002

1 1991

Wyniki wyszukiwania

Supernormal excitability in the Luo-Rudy I model of the mammalian ventricular cell

Myocardial calcium compartmentation and contractile control