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Early release of neutrophil chemotactic factor from isolated rat heart subjected to regional ischaemia followed by reperfusion.

OBJECTIVE
The study was designed to demonstrate the time course of neutrophil chemotactic factor (NCF) release from blood-free isolated rat hearts and to clarify the characteristics of NCF in order to facilitate its identification.


METHODS
Coronary effluents were collected every minute from Langendorff perfused rat hearts during ligation of the left coronary artery for 40 min and reperfusion for 60 min. The neutrophil chemotactic activity in the effluents was assayed using modified Boyden's chambers with rat neutrophils isolated from peripheral blood as the indicator cells.


RESULTS
The NCF release started at 10 min of coronary artery occlusion. During the reperfusion period, NCF release peaked at 5 min (230% of preischaemic value). To clarify the characteristics of NCF, the changes in chemotactic activity were examined using various inhibitors and inactivators of possible NCF candidates (LTB4, PAF, 5-lipoxygenase, and thromboxane synthase). The heat stability of NCF was also examined to exclude heat labile molecules such as adenosine or complements appearing as NCF. Among the various substances examined, only PAF antagonists (CV-6209 and TCV-309 at concentrations of 10(-6) M and 10(-5) M respectively) abolished the chemotactic activity. However direct measurement of PAF in the effluents was unsuccessful.


CONCLUSION
NCF is released from the heart early after ischaemic insult, with the highest peak occurring at 5 min of reperfusion. PAF related substances might be the primary NCF in the effluent but this remains to be determined.