FIGURE 3.

Immunohistochemical localization in the renal cortex of the rate limiting enzyme in catecholamine production, tyrosine hydroxylase (TH; a–d; brown stain) in non-diabetic control and diabetic normotensive and hypertensive mice. Periodic acid Schiff’s (PAS) stain (pink) was used as a counterstain to distinguish proximal (PTs) and distal tubule (DTs) populations. Quantification of proximal tubules (e) and distal tubules (f) shows non-diabetic control hypertensive mice had a greater percentage area of staining for TH in proximal tubules compared to diabetic hypertensive animals. There were no significant differences between groups for the percentage area stained for TH in distal tubules. Renal cortical catecholamine content (g) for DOPA, dopamine, and norepinephrine. Note change in scale for norepinephrine. Hypertensive animals had significantly greater amounts of norepinephrine and dopamine. Diabetic animals had significantly less dopamine and norepinephrine content. Diabetic hypertensive mice retained significantly greater levels of dopamine and norepinephrine as compared to diabetic normotensive mice. n = 6–9/group. 2-factor ANOVA p-values: I=interaction, D=relative to diabetic status, S=relative to strain. t-test p < 0.05: ^∗ vs. Cont. Normot.; † vs. Cont. Hypert.; ‡ vs. Diab. Normot; TH staining in PTs Cont. Normot. vs. Cont. Hypert p = 0.06. DOPA- L-3,4-dihydroxyphenylalanine. Scale bar: 50 μm.