Summary

To investigate β₂-adrenergic agonist-mediated effects on coronaryfluxes of local fibrinolytic factors, healthy anaesthetisedand instrumented pigs (n=10) were studied during infusion ofisoprenaline (IPR) into the left main coronary artery. Coronarynet fluxes of total t-PA antigen, active t-PA and total PAI-1 antigenwere determined at baseline and at 3, 5, 7 and 10 minutesof IPR infusion. During IPR, net release of total t-PA increasedin a biphasic pattern with transiently high levels at 3 (+440 %)and 7 minutes (+620%) and returned towards baseline at 10minutes. Net coronary release of active t-PA increased withmaximum levels at 3 minutes (+50%). Baseline coronary netflux of total PAI –1 showed a decrease which was most pronouncedat 10 minutes.To conclude, a fast β₂ agonist-mediatedlocal release of t-PA into the coronary vasculature was demonstrated.For total t-PA, this response was characterised by abiphasic release profile.