DEXTRAN VS HYDROXYETHYLSTARCH IN INHIBITION OF POSTISCHEMIC LEUKOCYTEADHERENCE IN STRIATED-MUSCLE

Microvascular injury associated with ischemia/reperfusion (I/R) is cha racterized by both ''no reflow'' and ''reflow paradox.'' Prophylactic isovolemic hemodilution with dextran 60 to a hematocrit of 30% has bee n shown to prevent I/R-induced capillary no reflow in striated muscle. The objective of the present study was to analyze whether hemodilutio n prior to ischemia has the potential to reduce postischemic leukocyte -endothelium interaction, which is known to be one of the major compon ents of I/R-induced reflow paradox. Syrian golden hamsters (n = 21) we re fitted with a dorsal skinfold chamber, which contains striated musc le and subcutaneous tissue and allows for repetitive analyses of the m icrocirculation by means of intravital fluorescence microscopy. Four h r of pressure-induced ischemia and 30 min of subsequent reperfusion (c ontrols, n = 7) resulted in a significant (P < 0.05) increase of micro vascular leukocyte accumulation (40,630 +/- 12,731 mm(-3)) and adheren ce to the endothelial lining of postcapillary venules (74.2% +/- 11.5% ) when compared to preischemic baseline (7,502 +/- 1,700 mm(-3) and 3. 4% +/- 1.0%, respectively). Recovery was not complete after an observa tion period of 24 hr reperfusion [13,735 +/- 2,666 mm(-3) (P < 0.05) a nd 18.5% +/- 6.0% (P < 0.05)]. Prophylactic isovolemic hemodilution wi th 6% dextran 60 (Dx60) to a hematocrit of 30% (Dx60, n = 7) significa ntly attenuated postischemic leukocyte accumulation (23,402 +/- 13,837 mm(-3); P < 0.05 vs. controls) and adherence (22.6% +/- 6.4%; P < 0.0 5). In contrast, hemodilution with 6% hydroxyethylstarch 200/0.62 (Hes ) was not effective in reducing leukocyte accumulation (37,878 +/- 15, 178 mm(-3)), and attenuation of postischemic leukocyte adherence (46.6 % +/- 7.6%; P < 0.05 vs. controls) was significantly less pronounced c ompared to that in Dx60-treated animals (P < 0.05). We conclude that p rophylactic isovolemic hemodilution with Dx60 is superior to Hes for i nhibition of postischemic leukocyte adherence in striated muscle, prob ably due to a compound-specific pharmacologic effect. (C) 1993 Wiley-L iss, Inc.