1. Sodium transport and intracellular sodium content were studied in thymocytes of rats made hypertensive by treatment for 4 or 8 weeks with deoxycorticosterone (DOC) and salt (DOC/salt).
2. The systolic blood pressure in the DOC/salt animals was 152 ± sem 3 and 189 ± 3 mmHg after 4 and 8 weeks' treatment respectively. This was significantly higher than pressures in their respective controls (124 ± 4 and 126 ± 5 mmHg), which had been given 1% sodium chloride solution (171 mmol/l) only.
3. The total sodium efflux rate constant in the DOC/salt rats was lower than that in the control group after 8 weeks of treatment (5.56 ± sem 0.21 vs 6.12 ± 0.11 h−1; P < 0.05) but not after 4 weeks of treatment (5.93 ± 0.13 vs 6.32 ± 0.13 h−1;0.1 > P > 0.05).
4. Intracellular sodium content in the DOC/salt rats was significantly higher than that of the control animals after 8 weeks' treatment (49.6 ± 2.5 vs 42.1 ± 1.0 mmol/kg dry weight; P < 0.05).
5. No significant changes were observed in intracellular potassium content, sodium influx or ouabain-insensitive sodium efflux rate constant.
