Dw. Laight et al., ASSESSMENT OF MYELOPEROXIDASE ACTIVITY IN RENAL TISSUE AFTER ISCHAEMIA REPERFUSION/, European journal of pharmacology. Environmental toxicology and pharmacology section, 292(1), 1994, pp. 81-88
We have shown that a photometric assay of myeloperoxidase derived from
rat blood polymorphonucleocytes employing 3,3',5,5'-tetramethylbenzid
ine as substrate is more sensitive than an established assay employing
o-dianisidine. We went on to demonstrate that rat renal tissue is cap
able of inhibiting peroxidase activity. This activity approached 100%
when the rat renal supernate was incubated at 60 degrees C for 2 h and
the assay was conducted in the presence of a 10-fold higher concentra
tion of hydrogen peroxide (H2O2). Rat kidneys undergoing 45 min ischae
mia and 1, 3 and 6 h reperfusion in vivo, exhibited significant increa
ses in myeloperoxidase activity, indicating tissue polymorphonucleocyt
e accumulation. Monoclonal antibodies against rat intercellular adhesi
on molecule 1 (ICAM-1) and CD18 of beta(2),-integrins administered bot
h 5 min before a period of 45 min renal ischaemia (20 mu g/kg i.v.) an
d at the commencement of 1 h reperfusion (20 mu g/kg i.v.) reduced ren
al tissue polymorphonucleocyte accumulation. However, similar treatmen
t with the parent murine antibody immunoglobulin G1 (IgG1) and an unre
lated murine antibody, IgG2a, also significantly reduced renal tissue
polymorphonucleocyte accumulation. In conclusion, we demonstrate that
the rat renal suppression of peroxidase activity can be overcome by a
combination of heat inactivation and the provision of excess assay H2O
2. In addition, the available evidence suggests that murine monoclonal
antibodies against rat adhesion molecules may exert non-specific acti
ons in our model of renal ischaemia/ reperfusion in vivo.