Calcium depletion in rabbit myocardium. Calcium paradox protection by hypothermia and cation substitution.
- 1 August 1982
- journal article
- research article
- Published by Wolters Kluwer Health in Circulation Research
- Vol. 51 (2), 131-141
- https://doi.org/10.1161/01.res.51.2.131
Abstract
The purpose of this study was to define further the basis of control of myocardial membrane permeability by further examination of the "calcium paradox." To this end, the protective effect of hypothermia and addition of micromolar amounts of divalent cations during the Ca-free perfusion period were studied. Damage during Ca++ repletion to the isolated arterially perfused, interventricular rabbit septum was assessed by contracture development, loss of developed tension, and loss of 42K and creatine kinase. Progressive hypothermia prolongs the time of Ca-free perfusion needed to cause similar 42K, creatine kinase and developed tension losses upon Ca++ repletion. Complete protection against the Ca-paradox after 30-60 minutes Ca-free perfusion is seen at 18 degree C. The inclusion of 50 microM Ca++ during 30 minutes "Ca-free" perfusion also provides complete protection during Ca++ repletion i.e., there was full mechanical recovery with no 42K or creatine kinase loss. Other divalent cations perfused in 50 microM concentrations during the Ca-free period exhibited variable ability to protect when Ca++ was reperfused. The order of effectiveness (Ca++ greater than Cd++ greater than Mn++ greater than Co++ greater than Mg++) was related to the crystal ionic radius, with those cations whose radii are closest to that of Ca++ (0.99 A) exerting the greatest protective effect. The cation sequence for effectiveness in Ca-paradox protection is the same sequence for potency of excitation-contraction uncoupling. The mechanism of hypothermic protection is likely a phase transition in the membrane lipids (from a more liquid to a less liquid state) which stabilizes membrane structure and preserves Ca++ permeability characteristics during the Ca-free period. The mechanism of protection via cation addition is perhaps a cation's ability to substitute for Ca++ (dependent on unhydrated crystal ionic radius) at critical sarcolemmal binding sites to preserve control of Ca++ permability during the Ca-free period.This publication has 25 references indexed in Scilit:
- Temperature dependence of the calcium paradox in the isolated working rat heart: Discrepancy between functional recovery and enzyme release,Journal of Molecular and Cellular Cardiology, 1980
- Energy dependence of the calcium paradoxJournal of Molecular and Cellular Cardiology, 1978
- Spin label studies on rat liver and heart plasma membranes: Effects of temperature, calcium, and lanthanum on membrane fluidityJournal of Supramolecular Structure, 1978
- Changes in high-energy phosphate compounds of isolated rat hearts during Ca2+-free perfusion and reperfusion with Ca2+Journal of Molecular and Cellular Cardiology, 1976
- A biochemical and ultrastructural study of the species variation in myocardial cell damageJournal of Molecular and Cellular Cardiology, 1976
- Prevention by hypothermia of paradoxical calcium necrosis in cardiac muscleJournal of Molecular and Cellular Cardiology, 1975
- Structural and functional changes associated with failure and recovery of hearts after perfusion with Ca2+-free mediumJournal of Molecular and Cellular Cardiology, 1975
- The Influence of Changes in pH of the Perfusion Fluid on the Occurrence of the Calcium Paradox in the Isolated Rat HeartCardiovascular Research, 1969
- Morphological Changes of Heart Muscle Caused by Successive Perfusion with Calcium-free and Calcium-containing Solutions (Calcium Paradox)Cardiovascular Research, 1967