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Proceedings of the Australian Physiological and Pharmacological Society Symposium: New Frontiers in Muscle Research
Does Ca 2+ release from the sarcoplasmic reticulum influence heart rate?
Author(s) -
Ju YueKun,
Allen David G
Publication year - 2001
Publication title -
clinical and experimental pharmacology and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 103
eISSN - 1440-1681
pISSN - 0305-1870
DOI - 10.1046/j.1440-1681.2001.03506.x
Subject(s) - endoplasmic reticulum , chronotropic , pacemaker potential , increased heart rate , stimulation , biophysics , calcium , sodium calcium exchanger , medicine , reticulum , chemistry , heart rate , biology , membrane potential , biochemistry , blood pressure
SUMMARY 1. The present review summarizes the evidence that Ca 2+ release from the sarcoplasmic reticulum (SR) is an important contributor to the systolic rise in [Ca 2+ ] i (the Ca 2+ transient) and influences the pacemaker firing rate. 2. We believe that the mechanism whereby [Ca 2+ ] i influences firing rate is through the dependence of the Na + –Ca 2+ exchanger on [Ca 2+ ] i . 3. Extrusion of Ca 2+ by the electrogenic Na + –Ca 2+ exchanger produces an inward current that contributes to the pacemaker currents. Confocal images of Ca 2+ indicate the distribution of [Ca 2+ ] i and Ca 2+ sparks add to the evidence that Ca 2+ release from SR is involved in pacemaker activity. 4. The normal pathway for increased heart rate is sympathetic activation; we discuss the evidence that part of the chronotropic effect of β ‐adrenoceptor stimulation is through the modulation of SR Ca 2+ release. 5. These studies show that Ca 2+ handling by the pacemaker cells makes an important contribution to the regulation of pacemaker activity.