Effect Of Hypothermic Preservation Research Articles

Differential time scale of fluid and solute permeability following hypothermic lung preservation

Background Assessment of the quality of lung graft preservation by simple functional measures in some laboratory models may fail to detect endothelial injury. The effects of hypothermic preservation in isolation were investigated by measuring the pulmonary capillary filtration coefficient (Kf) and the albumin surface area product (PS) at various cold ischemic intervals. Methods Rat lungs were flushed with University of Wisconsin solution at 4° C. Following storage at 4° C, lungs for Kf measurement were subjected to a change in pulmonary arterial pressure. Kf was calculated from the change in rate of weight gain as a function of hydrostatic stress. PS lungs were exposed to Tris buffered Ringer’s solution containing I 125 albumin (20 μM) in an isogravimetric state. Following a vascular flush the lungs were homogenized and underwent scintillation counting. Using the Kedem-Katchalsky equation PS was calculated. Results The Kf for the control, 4-hour, and 7-hour groups were 0.778, 1.816, 4.853 g/cm H 2O/min/100 g wet lung tissue, respectively. There was a significant increase in Kf with each time increment ( P,0.01). The Kf for the 24-hour group was 5.587 g/cm H 2O/min/100 g wet lung tissue; not an additional significant increase. PS for the control and 4-hour groups (0.0115 and 0.0101 cm 3/g wet lung tissue/minute, respectively) were not significantly different. After 7 hours there was a significant increase to 0.171 cm 3/g wet lung tissue/min. PS could not be measured after 24 hours. Conclusions Significant endothelial injury occurs after 4 hours of cold ischemic preservation. There is progressive injury with time. Increase in water permeability is not secondary to increase in albumin permeability.

PHOSPHOLIPID METABOLISM IN THE HYPOTHERMIC LIVER

39 The activity of phospholipase A2 (PLA2) on membrane-bound phospholipids (PLs) during cold storage (CS) is a cause of liver injury due to: 1)loss of membrane structural and functional integrity, 2)generation of cytotoxic level of free fatty acids, and 3)formation of detergent-like, lysoPL compounds. In this study we show that not only are PLA2 active during CS of the liver, but also fatty acid acylation of PLs occurs rapidly. The continued activity of enzymes involved in PL metabolism may be a major cause of membrane alterations in the CS liver that leads to organ failure on reperfusion (transplantation). Rat hepatocytes (Hc) were CS (4°C) for up to 48 hours and rate of incorporation of radiolabelled arachadonic acid (AA) into specific PLs measured. PLs were extracted and separated by conventional thin layer chromatography (TLC) methods. The isolated and identified PL was used for determination of amount of radiolabelled AA. The results shown are for at least three separate Hc preparations. (PC = phosphatidylcholine, PE = phosphatidylethanolamine) Table The rate of incorporation of AA into specific PL species was not decreased by hypothermia. Also, there was no significant loss of PL species as judged by phosphorus analysis of the TLC spots. The rate of incorporation into PC, PE, PS (not shown) and PI (not shown) was nearly complete within one hour of incubation at both 37°C and 4°C in both L-15 tissue culture medium or UW solution. The incorporation was ATP dependent (blocked by KCN and iodoacetate) indicating a role for the ATP-dependent fatty acid acyltransferase in the incorporation of AA into PLs. Also, the incorporation was blocked by PLA2 inhibitor (trifluoroperazine) showing the role of PLA2 in the reaction. Thus, the acylation-deacylation of fatty acids that occurs at normothermia, occurs at a similar rate at hypothermia (4°C). The implications of this for liver preservation are: 1)acylation-deacylation is an important energy consuming reaction that can contribute to the energy deficit in the cold stored liver, 2)acylation-deacylation will lead to a restructuring of cellular and organelle membranes, contributing to abnormal cellular transport functions, and 3)PLA2 activity is not significantly suppressed by hypothermia. We will discuss how the effects of hypothermic preservation on liver PL metabolism can lead to methods to improve organ preservation.Table

Description and interpretation of structural changes in canine kidneys after preservation with a hyperosmolar solution and reperfusion

The effects of hypothermic preservation of canine kidneys for 24 hours by the use of the Sacks solution, and additional autogenous reperfusion were studied by means of submicroscopic morphological methods. While preservation with the Sacks solution was to ensure normal organization of the lipoprotein structures of the basement and cell membranes, in case of additional reperfusion, even of short duration, a substantial or complete loss of anisotropy of the cytomembranes was demonstrable. The present report is the first to be published in the literature on polarization microscopic studies concerned with the effects of kidney preservation and of reperfusion.