Effects of Nutrient and Hemoglobin Enriched Cell Free Perfusates Upon Ex Vivo Isolated Rat Heart Preparation

Abstract

We evaluated the effects of nutrient enriched medium and hemoglobin based oxygen carrier (HBOC) upon myocardial functional recovery after 15 minutes of warm ischemia in an isovolumic Langendorff rat heart model. Hearts (n = 8/group) were perfused at constant pressure (90 mm Hg) with Krebs-Henseleit buffer or HEPES modified cell culture medium (M199) in the absence and presence of HBOC. Hearts received 15 minutes of normothermic no flow ischemia followed by 60 minutes reperfusion. Hemodynamics, coronary flow, and tissue water content were measured, and microscopic evidence of injury including TUNEL assay was assessed. Preischemic left ventricular performance (left ventricular developed pressure and maximum rate of positive and negative change in systolic pressure) and coronary flow were similar among groups. At 60 minutes of reperfusion, M199 alone provided more stable and complete left ventricular systolic and diastolic functional recovery than any other perfusate. Coronary flow rates reflected left ventricular function observed under each perfusate condition. TUNEL assay showed arterial endothelial cell death in some hearts perfused with HBOC. Tissue water content did not reflect functional recovery. The combination of M199 and HBOC was associated with poor recovery and elevated perfusate methemoglobin. In this system, postischemic dysfunction is prevented by components in M199. Added HBOC does not improve functional recovery and negates the salutary effects of M199, possibly by augmenting methemoglobin formation.

Acute exercise exacerbates ischemia-induced diastolic rigor in hypertensive myocardium

“…The heart was then passively desiccated at 37.5°C until a stable dry weight was achieved. Tissue water content was calculated as ([wet weight-dry weight]/dry weight) and expressed as ml H 2 O/gm dry weight as previously described by our group (Mohara et al 2005). …”

Role of Endothelial Cells in Myocardial Ischemia-Reperfusion Injury

“…We and others have demonstrated in an isolated heart model that immediately following an IR insult, vascular function strongly correlates with cardiac function [ 86 , 98 , 99 ]. In isolated rat hearts pretreated with verapamil prior to subjecting the organs to 30 minutes of no flow, preservation of coronary flow was significantly correlated with functional recovery ( Fig.…”

“…2 ). These improvements were associated with decreases in histopathological markers (NF-kB translocation and apoptosis) in EC [ 98 ]. In both treated and untreated hearts, minimal cardiomyocyte damage was noted.…”

“…Drug treatment is often protective when administered prior to ischemia [ 86 , 88 , 89 , 98 , 99 , 111 , 147 – 154 ]. These drugs include insulin, adenosine and adenosine agonists, bradykinin, statins, cariporide, cyclosporine (CSA), and sanglifehrin A (SFA).…”

“…Cardiac functional measurements were obtained immediately at the end of reperfusion. Left ventricular (LV) developed pressure (LVDP, mmHg), and positive and negative (−) LV dP/dt (mm Hg/sec) correlated significantly with coronary flow [ 98 ].…”