THE EFFECTS OF RECOMBINANT HUMAN GRANULOCYTE-COLONY-STIMULATING FACTOR ON VASCULAR DYSFUNCTION AND SPLANCHNIC ISCHEMIA-REPERFUSION INJURY

1 The aim of our study was to investigate the effects of recombinant h uman granulocyte-colony stimulating factor in a rat model of splanchni c ischaemia-reperfusion injury. 2 Male anaesthetized rats were subject ed to clamping of the splanchnic arteries for 45 min. This surgical pr ocedure resulted in an irreversible state of shock (splanchnic artery occlusion shock; SAO shock). Sham operated animals were used as contro ls. Survival rate, serum tumour necrosis factor-alpha (TNF-alpha), neu trophil count, bone marrow myeloid precursor cells, myeloperoxidase ac tivity (MPO; studied as a quantitative means to assess leukocyte accum ulation), mean arterial blood pressure and the responsiveness of aorti c rings to phenylephrine (PE, 1 nM-10 mu M) were studied. 3 SAO shocke d rats had a decreased survival rate (0% at 4 h of reperfusion, while sham shocked rats survived more than 4h), increased serum levels of TN F-alpha (201+/-10 u ml(-1); sham shocked rats=undetectable), neutropen ia, enhanced MPO activity in the ileum (0.11+/-0.06 u x 10(-3) g(-1) t issue; sham shocked rats=0.02+/-0.001 u x 10(-3) g(-1) tissue) and in the lung (1.5+/-0.2 u x 10(-3) g(-1) tissue; sham shocked rats=0.19+/- 0.05 u x 10(-3) g(-1) tissue) and unchanged bone marrow myeloid precur sor cells. Furthermore aortic rings from shocked rats showed a marked hyporeactivity to PE. 4 Administration of recombinant human granulocyt e colony stimulating factor (rh G-CSF; 5, 10 and 20 mu g kg(-1) 5 min following the release of occlusion) increased in a dose-dependent mann er survival rate (90% at 4 h of reperfusion with the dose of 20 u x 10 (-3) g kg(-1)), reduced serum TNF-alpha (13+/-5 u ml(-1)) and MPO acti vity in the ileum (0.065+/-0.002 u x 10(-3) g(-1) tissue) and in the l ung (0.7+/-0.03 mu g kg(-1) tissue), improved neutropenia and mean art erial blood pressure but did not modify bone marrow myeloid progenitor cells. Furthermore rh C-CSF, either in vivo or in vitro (200 nM for 1 h in the organ bath), restored to control values the hyporeactivity t o PE. Finally rh G-CSF potently inhibited the activity of inducible ni tric oxide synthase in peritoneal macrophages activated with endotoxin . 5 Our results suggest that rh G-CSF protects against splanchnic isch aemia reperfusion injury by a mechanism(s) that does not depend upon i ts haematopoietic effects.