European Journal of Cardio-Thoracic Surgery, Vol 11, 338-342, Copyright © 1997 by European Association for Cardio-thoracic Surgery
In vitro pulmonary arterial relaxation after experimental lung transplantation with extracorporeal circulation
S Kukkonen, T Siltanen and P Aarnio
Department of Anesthesiology, Helsinki University Central Hospital, Finland.
OBJECTIVE: In search of an agent to attenuate the increased pulmonary
vascular resistance after lung transplantation with extracorporeal
circulation, we investigated contractions and relaxations of isolated
porcine pulmonary arterial rings in organ chambers. METHODS: Rings of
arteries from three groups were studied. Rings from the heart-lung block
were studied immediately after Euro-Collins flush (n = 6). Rings from the
recipient's native (n = 5) and transplanted (n = 5) lung were studied after
3 h of right heart bypass following transplantation. The duration of cold
ischemia of the transplanted lung was 3-4 h. Contractions to potassium
chloride and phenylephrine were measured. In order to study relaxations,
the rings were preconstricted with phenylephrine. Relaxations to
acetylcholine, adenosine diphosphate and isoproterenol were determined in
rings with endothelium, and relaxations to sodium nitroprusside in rings
without endothelium. RESULTS: Sodium nitroprusside induced complete
relaxations (100%) in rings of arteries from all three groups. Relaxations
to acetylcholine and adenosine diphosphate were comparable among the three
groups, but relaxations to isoproterenol were significantly depressed in
pulmonary artery rings from the transplanted lung, compared with those from
the native lung. CONCLUSIONS: Lung transplantation with extracorporeal
circulation is associated with depressed beta-receptor-mediated
vasodilation, but the pulmonary vascular smooth muscle cell's ability to
relax is not affected.
