Heart slice NMR

Abstract

Nuclear magnetic resonance (NMR) spectroscopy of the heart is normally carried out using whole heart preparations under coronary perfusion. In such preparations, either radical changes in ionic composition of the perfusate or applications of numerous drugs would affect coronary microcirculation. This report communicates the first31P NMR spectroscopy study using a heart slice preparation (left ventricular slices) superfused with extracellular medium. The ratio of phosphocreatine concentration to ATP concentration was ∼2.1. Also, intracellular pH and Mg2+concentration ([Mg2+]i), estimated from the chemical shifts of inorganic phosphate and ATP, were comparable with those under retrograde perfusion. [Mg2+]iwas significantly increased by the removal of extracellular Na+, supporting the essential role of Na+-coupled Mg2+transport in Mg2+homeostasis of the heart. Heart slice preparation could also be used to evaluate the potency of cardiac drugs, regardless of their possible effects on coronary microcirculation.