Ouabain‐sensitive (OS) O2consumption was determined in proximal tubular cells from weanling rats fed 21 % (normal‐protein, NP) or 50% (high‐protein, HP) protein diet for 4 days. Butyric acid 10‐3M was added as a substrate for mitochondrial respiration and the ionophore amphotericin B (10 μ ml‐1) was used to sodium‐load the cells. OS respiration was higher in HP than in NP cells in both DME and amino acid‐free electrolyte solution (ES). Amphotericin B significantly increased OS respiration in both NP and HP cells, implying that the Na‐K pump was activated by increased intracellular Na. In cells incubated in ES, addition of amino acids stimulated OS respiration significantly in HP cells (16.9 ± 1.4vs21.2 ± 1.1 nmol min‐1mg‐1protein) and in NP cells (13.9 ± 0.3vs14.9 ± 0.6 nmol min‐1mg‐1protein). Stimulation was significantly higher in HP cells (26 ± 4%) than in NP cells (7 ± 4%) (P<0.001). The amino acids did not stimulate ouabain‐insensitive respiration.The results indicate that an HP diet to weanling rats will increase proximal tubule cell Na, K‐ATPase‐dependent respiration by enhancing Na