Quinidine enhances intracellular Ca 2+ accumulation during rapid stimulation
1. 1. The quinidine-induced modification of intracellular Ca 2+ concentration ([Ca 2+] i) was studied in guinea-pig myocardium using fura-2. Quinidine reduced the systolic fluorescence signal level for [Ca 2+] i and enhanced the end-diastolic signal level during a stimulation train. 2. 2. The diasto...
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Published in | General pharmacology Vol. 26; no. 5; pp. 971 - 976 |
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Main Authors | , , , , , , |
Format | Journal Article |
Language | English |
Published |
Elsevier Inc
1995
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Subjects | |
Online Access | Get full text |
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Summary: | 1.
1. The quinidine-induced modification of intracellular Ca
2+ concentration ([Ca
2+]
i) was studied in guinea-pig myocardium using fura-2. Quinidine reduced the systolic fluorescence signal level for [Ca
2+]
i and enhanced the end-diastolic signal level during a stimulation train.
2.
2. The diastolic decay of [Ca
2+]
i fitted 2 exponential curves. Quinidine distorted the stimulation frequency-dependent acceleration of rapid [Ca
2+]
i decay, and prolonged the mean time constant of rapid decay after 2 Hz stimulation, from 154.4 to 205.3 msec (20 μM), and to 259.7 msec (60 μM quinidine). The time constant of slow recovery from [Ca
2+]
i accumulation after the stimulation train was not affected by stimulation frequency, or by quinidine, or caffeine.
3.
3. These results suggest that quinidine modulates [Ca
2+]
i via a balance between the slowing of rapid [Ca
2+]
i decay and the reduction of the systolic [Ca
2+]
i. This effect may contribute to the anti-arrhythmic and pro-arrhythmic effects exerted by quinidine in some conditions. |
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ISSN: | 0306-3623 1879-0011 |
DOI: | 10.1016/0306-3623(94)00297-Z |