Hypertonic saline and dextran: impact on cardiac function in the isolated rat heart

Area of Science:

• Cardiovascular Physiology
• Resuscitation Medicine
• Pharmacology

Background:

• Hypertonic saline with dextran (HSD) is a novel prehospital treatment for hemorrhagic shock.
• Its effects on cardiac function, particularly during ischemia-reperfusion, require detailed investigation.

Purpose of the Study:

• To evaluate the impact of hypertonic saline (7.5% NaCl) and dextran on non-ischemic and post-ischemic rat hearts.
• To elucidate the specific contributions of saline and dextran to cardiac function during resuscitation.

Main Methods:

• Isolated rat hearts were subjected to global ischemia and reperfusion.
• Hearts were perfused with 0.9% NaCl (control), 7.5% NaCl/dextran, 7.5% NaCl alone, or dextran alone.
• Ventricular function (developed pressure, contractility, relaxation rate) and coronary flow were measured.

Main Results:

• 7.5% NaCl alone or with dextran impaired ventricular function in non-ischemic hearts.
• Hypertonic saline with dextran, dextran alone, or sucrose improved post-ischemic cardiac function recovery.
• Dextran, but not sucrose, reduced myocardial hydrogen peroxide levels during ischemia and reperfusion.

Conclusions:

• 7.5% NaCl directly depresses myocardial function.
• Dextran contributes to improved post-ischemic cardiac recovery, partly by reducing oxidative stress (hydrogen peroxide).
• The benefits of HSD in shock resuscitation are likely due to dextran's properties, not the saline component.