Leukocyte Redistribution and Eicosanoid Changes During the Autoperfused Working Heart-Lung Preparation

Abstract

We studied the role of leukocyte redistribution and eicosanoid changes in the early stages of instituting 16 rabbit autoperfused working heart-lung preparations (A WHLP). Physiological changes occurring during the transition from the intact animal to the A WHLP may determine the survival and viability of the organ blocks for transplantation. White blood cell (WBC) count decreased from 5160/μL to 1430/μL (P <. 01) at 60 min of autoperfusion. Differential WBC counts performed in ten of these A WHLP revealed a 63% decrease in lymphocyte count and an 88% decrease in the granulocyte count at 60 min. Thus, the predominant leukocyte remaining in the circulation was the lymphocyte. Blood samples were collected from the intact animal and from the A WHLP for assay of the stable metabolites of thromboxane A₂ (TxA₂) and prostacyclin (PGI₂). Transition from the in situ heart-lung block to the in vitro A WHLP stage caused significant changes in these metabolites. The PGI, metabolite 6-ketoprostaglandin F1, (6KPGF1_a) increased from 2680 ± 487 to 4339 ± 478 (pg/mL), P <. 05, while the TxA₂ metabolite, thromboxane B₂ (TxB₂) decreased from 618 ± 105 to 289 ± 63 (pg/mL). However. assays of 11-dehydro-TxB₂ (11-DHT), a longer lived metabolite of TxA₂ (n = 7) increased (668.4 ± 84.6 to 946.4 ± 43.7, P <. 05). The transition from the in situ heart-lung block of the intact animal to the A WHLP involves significant physiological changes. Redistribution of leukocytes occurs with a predominant decrease in the granulocyte count. while levels of bioactive lipid mediators show a distinct large rise in the PGI₂ metabolites and a lesser increase in TxA₂ metabolites. These early changes may play a complex critical role in the pulmonary injury leading to the failure of the A WHLP.

Key Words:

• Eicosanoid
• leukocytes
• auto-perfusion