Cold preservation-warm reperfusion perturbs cytosolic calcium ion homeostasis in rat liver sinusoidal endothelial cells.

Abstract

Increases in intracellular calcium ion (Ca(2+)) levels of sinusoidal endothelial cell (SEC) may have a crucial role in mediating the expression of adhesion molecules and thus contribute to the microcirculatory disturbances observed in primary graft dysfunction. The effect of changes in the composition and/or temperature of the reperfusion solution on cytosolic Ca(2+) was studied in isolated rat SECs. Cells were preserved in cold University of Wisconsin (UW) solution for 0, 12, or 24 hours and loaded with Fura-2AM dye (Cedarlane, Eugene, OR) at 20 degrees C in N-2-hydroxyethylpiperazine-propanesulfonic acid (HEPES)-buffered physiological solution (HEPES 20 degrees C) or UW solution (UW 20 degrees C). SEC Ca(2+) levels were measured by cytofluorimetry. Basal steady-state Ca(2+) levels were much lower when SECs were loaded in UW 20 degrees C (37 +/- 2 nmol/L) than in HEPES 20 degrees C (114 +/- 32 nmol/L). In unstored controls (0 hour), going from UW 20 degrees C to HEPES 37 degrees C induced a large transient increase (185 +/- 31 nmol/L) in SEC Ca(2+) levels, which was greatly inhibited (43 +/- 13 nmol/L) in Ca(2+)-free HEPES 37 degrees C. A similar large transient increase was observed going from UW 20 degrees C to HEPES 20 degrees C (163 +/- 22 nmol/L). Changing temperature only (20 degrees C to 37 degrees C) in UW or HEPES solution had a much smaller effect on SEC Ca(2+) levels (14 +/- 2 and 60 +/- 18 nmol/L, respectively). These changes were similar in cold-preserved cells. In unstored controls, solution changes greatly attenuated the intensity of subsequent Ca(2+) responses to the purinergic agonist adenosine triphosphate (ATP). Cold preservation (CP) greatly attenuated both the frequency of appearance and intensity of ATP-induced Ca(2+) responses. Hence, changing reperfusion solution composition has a greater impact on SEC steady-state Ca(2+) levels than changing temperature. Cold preservation does not significantly affect changes in SEC steady-state Ca(2+) levels, but greatly impairs the capacity of SECs to subsequently respond to Ca(2+)-mobilizing agonists.