Fig. 3.

A: representative RT-PCR assays of afferent arterioles using the α, β, and γ₁ nested primers (Table 1, 35 + 35 cycles) and single (300 μm) segment of the cortical collecting duct (CCD). Nos. in parentheses indicate frequency of observation in all 20 kidney preparations. B: with the use of the α, β, and γ₂ primers (Table 1), mRNA for all three epithelial Na⁺ channel (ENaC) subunits could be detected in 10 CCD epithelial cells but not in 10 afferent arterioles (∼1,000 cells). C: same assay could detect ENaC subunit expression in an intact interlobar artery but not in isolated interlobar myocytes (see text for description).