The isolated rat heart perfused with washed platelets was used as a model to examine platelet-vessel wall interactions. Release of prostacyclin and thromboxane A2 was measured, using a cascade of smooth muscle bioassay tissues or radioimmunoassays of the stable hydration products. In hearts perfused with rabbit or human platelets, injection of sodium arachidonate caused release of both prostacyclin and thromboxane A2. In hearts perfused with aspirin-pretreated platelets, arachidonate released only prostacyclin indicating that thromboxane A2 originates largely in the platelets. Infusion of epinephrine (0.6-6 nmol/liter) through the heart potentiated arachidonate-induced release of thromboxane A2. Similar potentiation of thromboxane A2 release was observed in rat hearts perfused with either rabbit or human platelets, and in rabbit hearts perfused with rabbit platelets. In contrast, when rabbit platelets were infused through an incubation coil of tubing in place of the heart, epinephrine did not alter thromboxane A2 release. There was no significant loss of rabbit platelets on perfusion through rat hearts, and no aggregates were observed in the effluent either before or immediately after arachidonate injections, even in the presence of epinephrine. Thus, potentiation of thromboxane A2 production could not be explained by aggregation. However, it is clear from these studies that physiological concentrations of epinephrine can potentiate thromboxane A2 release from platelets when they are stimulated by arachidonic acid within the heart. This could result from a redirection of arachidonate metabolism to a local potentiating factor in the vessel wall. Potentiation of thromboxane A2 release might contribute to myocardial ischemia associated with platelet activation.

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In this essay, we set out to explore the ways in which our approaches and assumptions around internationalisation, and the experiences of international students, have been challenged. Drawing on our experiences as academics through the transitioning times over the last two years, we have chosen to approach this through a series of reflections on four themes: university as an imagined community, globalisation, home not as a metaphor, and a journey toward humility. Through this essay, we invite discussions on these topics to foster excellence in teaching and learning internationalisation in the higher education sector.