Fig. 1.

Uptake of ¹²⁵I-angiotensinogen in isolated proximal tubules. A: schematic of the ¹²⁵I-angiotensinogen uptake assay and subcellular fractionation. ¹²⁵I-angiotensinogen (20 nM) was incubated with isolated sheep renal proximal tubules (500 µg protein) for 2 h at 37°C. B: distribution of extracellular and intracellular ¹²⁵I-angiotensinogen. Data are mean ± SE expressed a %initial cpm; n = 4. Inset: subcellular fractionation revealed that 21 ± 4% of internalized ¹²⁵I-angiotensinogen associated with the mitochondrial (Mito) fraction, with additional labeling in the nucleus (Nuc; 60 ± 7%), endoplasmic reticulum (ER, 4 ± 0.5%), and cytosol (15 ± 4%). Data are means ± SE expressed as the %total intracellular cpm; n = 4.