Improved rat heart function after low Ca2+ perfused preservation at 5 degrees C for 18 hours

Area of Science:

• Cardiology
• Cardiovascular Physiology
• Organ Preservation

Background:

• Hypothermic preservation is crucial for organ transplantation.
• Maintaining cardiac function post-preservation is a significant challenge.
• Calcium ion (Ca2+) overload can impair heart recovery after cold storage.

Purpose of the Study:

• To investigate the impact of varying calcium (Ca2+) concentrations on isolated rat heart function recovery after hypothermic preservation.
• To determine the optimal Ca2+ level for mitigating functional decline during and after cold storage.

Main Methods:

• Isolated working rat hearts were perfused at 37°C, cooled to 5°C, and preserved for 1, 6, or 18 hours.
• Perfusion solutions with different Ca2+ concentrations (0.35-2.0 mM) were used during cooling, preservation, and rewarming.
• Contractile functions, including heart rate (HR), left ventricular systolic pressure (LVSP), maximal rate of pressure development (+dP/dtmax), and coronary flow (CF), were assessed post-rewarming.

Main Results:

• Complete recovery was observed after 1 hour of preservation in normal Ca2+ (2.0 mM).
• Significant functional loss occurred after 6 hours, and further deterioration (decreased LVSP, +dP/dtmax, CF; increased diastolic pressure) after 18 hours at 5°C.
• Reducing Ca2+ to 0.5 mM prevented functional deterioration during prolonged hypothermic preservation (up to 18 hours).
• Ca2+ levels below 0.5 mM (e.g., 0.35 mM) led to reduced recovery.

Conclusions:

• Reducing extracellular Ca2+ concentration prior to and during hypothermic preservation is effective in preventing cardiac dysfunction.
• Perfusion with 0.5 mM Ca2+ K-H solution optimizes cardiac preservation, extending preservation time and maintaining functional integrity upon rewarming.
• This strategy offers significant benefits for improving outcomes in cardiac preservation and transplantation.