Recent studies revealed an additive cardiodepressive effect of polymorphonuclear granulocytes (PMN) and thrombocytes in hearts exposed to a no-flow
ischemia. To find out whether or not this is also true for isolated guinea pig hearts exposed to a low-flow
ischemia, the current study was performed. PMN or thrombocytes, together or separately, were applied as a 1-min bolus (1,000/microl or 20,000/microl, respectively) during
ischemia or in reperfusion in the presence of
thrombin (0.3 U/ml perfusate). Recovery of external heart work and intracoronary cell retention were quantified in percent. Sole application of PMN or platelets during
ischemia and reperfusion significantly compromised myocardial function, whereas coapplication of PMN and platelets did not exhibit any further cardiodepressive effect. Coapplication of cells almost prevented intracoronary platelet retention during
ischemia and in reperfusion, as opposed to sole platelet application. Known blockers of endogenously released anti-platelet substances like
nitric oxide, PGI(2) or
adenosine did not mediate a further aggravation of myocardial dysfunction. The
platelet-activating factor (PAF) antagonist
WEB 2170 BS, however, significantly improved recovery of external heart work during
ischemia and in reperfusion. This indicates that an additive cardiodepressive effect of PMN and platelets in working guinea pig hearts exposed to a low-flow
ischemia, cannot be demonstrated, whereas PAF antagonists seem to be cardioprotective, under these conditions. Even addition of
fibrinogen to the perfusate, did not show an additive cardiodepressive effect of coapplication of PMN and platelets.