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Effects of Ca2+ and epinephrine on Ca2+ recirculation fraction and total Ca2+ handling in canine left ventricles
- Source :
- The Japanese journal of physiology. 48(2)
- Publication Year :
- 1998
-
Abstract
- We investigated the effects of intracoronary Ca2+ and epinephrine on the intracellular Ca2+ recirculation fraction (RF) and total Ca2+ handling in the left ventricle (LV) of the excised cross-circulated canine heart preparation. We analyzed LV postextrasystolic potentiation (PESP) following a spontaneous extrasystole that occurred sporadically under constant atrial pacing. All PESPs decayed in alternans and none decayed monotonically. We extracted an exponential decay component from the alternans PESP, determined its beat constant (taue), and calculated RF = exp(-1/taue). Increased intracoronary Ca2+ slightly increased taue and RF, but epinephrine did not change them, although both agents enhanced LV contractility 2-3 times. Neither Ca2+ nor epinephrine affected the sinusoidal decay of the alternans PESP. These results indicate that RF via the sarcoplasmic reticulum was slightly augmented by Ca2+, but not by epinephrine. We combined these RF data with LV Ca2+ handling O2 consumption data and obtained 40-110 micromol/kg as the total amount of Ca2+ handled in one cardiac cycle in the control and enhanced contractile states. These results indicate that this new LV-level approach seems to better the understanding of the Ca2+ mass dynamics responsible for the mechanoenergetics enhanced by inotropic interventions.
- Subjects :
- Inotrope
medicine.medical_specialty
Cardiac Complexes, Premature
Epinephrine
Physiology
chemistry.chemical_element
Beat (acoustics)
Calcium
Ventricular Function, Left
Contractility
Coronary circulation
Dogs
Oxygen Consumption
Internal medicine
Coronary Circulation
medicine
Animals
Cardiac cycle
Myocardium
General Medicine
Myocardial Contraction
medicine.anatomical_structure
chemistry
Ventricle
Cardiology
medicine.drug
Subjects
Details
- ISSN :
- 0021521X
- Volume :
- 48
- Issue :
- 2
- Database :
- OpenAIRE
- Journal :
- The Japanese journal of physiology
- Accession number :
- edsair.doi.dedup.....647abd219b4ed719b2ad8992b88edf58