Improved functional recovery of the atherosclerotic rabbit heart subjected to normothermic global ischemia
Toleikis, P.M.; Tomlinson, C.W.
Canadian Journal of Cardiology 3(7): 345-350
1987
ISSN/ISBN: 0828-282X PMID: 3427533 Document Number: 292006
Contractile function before, during and after a period of ischemia was evaluated in perfused hearts from rabbits fed either 2% cholesterol or a control diet for two months. Rabbits were sacrificed and the hearts were perfused by the Langendorff normothermic perfusion technique. After a 30-min baseline period, the hearts were subjected to a 60-min period of low flow ischemia (0.2 mL/min) with Krebs-Henseleit solution containing either 2.5mM (normocalcemic) or 0.5 mM (hypocalcemic) calcium. Subsequently the hearts were reperfused for 30 mins. No significant differences in baseline contractile function (expressed by developed pressure and dP/dtmax) were observed between hearts from cholesterol-fed and control rabbits. Although, initially the degree of contracture, as measured by an increase in end diastolic pressure from baseline, was less in cholesterol-fed rabbit hearts, this difference did not persist beyond 40 mins of ischemic perfusion. Hypocalcemic ischemic perfusion was associated with a delay in development of contracture relative to normocalcemic perfusion in the hearts from cholesterol-fed rabbits. These results suggest an early resistance to ischemia by hearts from cholesterol-fed rabbits. Upon reperfusion, the hearts from control rabbits exhibited a sudden increase in contracture following ischemic perfusion with 0.5 mM calcium which was not observed in the hearts from rabbits fed a cholesterol diet. There was improved functional recovery and less contracture development post reperfusion in the hearts from cholesterol-fed rabbits, independent of the concentration of calcium used during ischemia. These data support the concept that transient ischemia of hearts made mildly atherosclerotic by chronic administration of a high cholesterol diet is: not associated with baseline functional deterioration as reflected by developed pressure or dP/dtmax; accompanied by a relative resistance to the effects of ischemia and reperfusion; and less susceptible to the influence of altered extracellular concentrations of calcium during a period of ischemia.