Experiments were performed to evaluate the
hypothesis that the early stage of Type 1 diabetes
mellitus (DM) increases renal angiotensin
II (AngII) concentration and angiotensin type 1
(AT1) receptor protein levels. Nineteen or twenty
days after vehicle (Sham rats) or streptozotocin
(STZ rats) treatment, plasma [AngII] was
higher in STZ rats (152±23 fmol/ml) than in
Sham rats (101±7 fmol/ml); however, kidney
[AngII] did not differ between groups. AT1
receptor protein expression was greater in STZ
kidneys than in Sham kidneys. This increase
was restricted to the cortex, where AT1 protein
levels were elevated by 77±26% (42 kDa) and
101±16% (58 kDa) in STZ kidneys.
Immunohistochemistry revealed this effect to
be most evident in distal nephron segments
including the connecting tubule/cortical collecting
duct. Increased renal cortical AT1 receptor
protein and circulating AngII levels are consistent
with an exaggerated AngII-dependent
influence on renal function during the early
stage of DM in the rat.