Changes in proteasome activity in the ischemic kidney of rat with experimental renovascular hypertension.

A long-lasting renal ischemia, followed by the left renal artery clipping (two-kidney, one clip Goldblatt model in rats) led to a marked decrease in proteasome chymotrypsin-like activity in the ischemic kidney. This activity was, however, significantly raised upon the stimulation with an artificial 20S proteasome activator SDS (0.025%). No changes were observed in either the levels of the constitutive 20S proteasome subunit (alpha5) or of its protein activator, PA28alpha, in the kidneys by Western blot. These preliminary results indicate that an inhibition of proteasome activity may result from a dissociation of the active proteasome complexes into the inactive 20S proteasome and its endogenous activators after a long-lasting renal ischemia.