Ventricular cycle length irregularity affects the correlation between ventricular rate and coronary flow in isolated, Langendorff perfused guinea pig hearts

Abstract

In isolated hearts, cycle length irregularity increases the slope of the positive linear correlation between mean ventricular rate and coronary flow via producing beats in which left ventricular pressure remains below perfusion pressure. This means that changes in rhythm have the capacity to influence coronary flow independently of heart rate in isolated hearts perfused at constant pressure, which should be noted in drug studies on arrhythmias performed in Langendorff hearts.

Graphene Oxide Significantly Modifies Cardiac Parameters and Coronary Endothelial Reactivity in Healthy and Hypertensive Rat Hearts Ex Vivo

“…The instability of the dispersion can possibly modify the particle effects by lowering the effective blood concentration by aggregation at the injection site or at the first line of organ capillaries that can effectively filter the largest particles . This hindrance derives from the fact that the blood and isotonic perfusion buffersused in the ex vivo heart perfusion studiescontain relatively high concentrations of calcium, magnesium, and sodium cations − that can instantly precipitate GO in vitro and shortly after a tissue or vein injection. , The aggregation of GO was observed at similar to isotonic levels of bivalent calcium and/or magnesium , or monovalent sodium cations, despite a high dispersibility of GO in water and the initial stability of such dispersions. The colloid stability of GO is improved with the increasing number of oxygen-containing functional groups; it can be modified by other functionalization routes or by changing their pH-dependent ionization degree. , …”