Retention of leucocytes in reperfused, isolated hearts does not cause haemodynamically relevant permanent capillary plugging

Abstract

Effects of microspheres (5 microns or 10 microns diameter) and polymorphonuclear leucocytes (PMN) on coronary resistance were compared in beating, non-working isolated guinea-pig hearts (Langendorff preparation). The hearts were buffer perfused (5 ml/min, constant flow) and particles or cells were infused into the coronary system as a bolus (1 ml, 1 min). Coronary perfusion pressure, coronary flow and formation of epicardial transudate were measured before and after bolus administration. Coronary resistance was estimated from these parameters. Retention of particles or cells was monitored by quantifying the numbers emerging in the coronary effluent in relation to the number administered. The effects of PMN were also studied after 15 min of global ischemia. Coronary resistance correlated with the number of 10-micron particles infused, which were almost quantitatively retained. In contrast, 5-micron beads had no such effect and were not retained in the coronary system. Though considerable numbers of PMN were retained in the hearts (about 21% under control conditions and 35% after ischaemia), coronary resistance was not increased in either case. Blockage of the CD18 adhesion complex by monoclonal antibodies lowered basal retention to 11% and completely prevented the elevation of retention by ischaemia. We conclude that, in this experimental model, PMN, permanently retained in the hearts under normal flow conditions and especially after brief ischaemia, do not cause acute, haemodynamically relevant capillary plugging, but adhere to postcapillary venules via CD18.

The impact of crystalloidal and colloidal infusion preparations on coronary vascular integrity, interstitial oedema and cardiac performance in isolated hearts

“…PMN of guinea pigs and humans show a quantitatively similar degree of adhesion in our model [12]. Therefore, the latter were used to substantially reduce the total number of animals needed.…”

“…Therefore, the latter were used to substantially reduce the total number of animals needed. Preparation, intracoronary application and counting of non-adherent human PMN, as well as calculation of their adhesion rate were carried out as described previously [12]. Under basal conditions intracoronary retention has been shown to be 21.6 ± 2.1% [12].…”

“…Preparation, intracoronary application and counting of non-adherent human PMN, as well as calculation of their adhesion rate were carried out as described previously [12]. Under basal conditions intracoronary retention has been shown to be 21.6 ± 2.1% [12]. Experimental shedding of the glycocalyx by intracoronary application of heparinase almost doubled this adhesion rate to 37.3 ± 2.0% [4,13].…”

Selectins and β 2 -integrins mediate post-ischaemic venular adhesion of polymorphonuclear leukocytes, but not capillary plugging, in isolated hearts

“…Reducing the number of PMN should not jeopardize the validity of our results because previous experiments in our model have demonstrated that the percentage of PMN retained in reperfused isolated hearts is independent of the number of PMN applied over the range of 0.6×10 6 -10×10 6 PMN [16]. Perfusion was then continued for 30 min at a constant flow of 300 ml/h to allow stabilization.…”

PMN/Platelets Coinfused in Guinea Pig Hearts Exposed to Low-Flow Ischemia Have no Additive Cardiodepressive Effect

“…Moreover, coronary perfusion pressure was quantified to exclude occurrence of significant capillary plugging. In recent studies, comparing the effects of microspheres (5 and 10 µm diameter) and PMN on coronary perfusion pressure of isolated and constant-volume perfused (5 ml/min) guinea pig hearts exposed to a 15-min ischemia, we could demonstrate that coronary perfusion pressure is a very sensitive parameter in order to exclude significant capillary plugging [12]. The cell activator thrombin was then administered throughout the whole constant-pressure ischemia/reperfusion phase in a concentration of 0.3 U/ml perfusion buffer.…”