RENAL ADAPTATION OF ADULT TRANSGENIC MREN2 RATS TO ORAL SODIUM LOAD

We compared the renal adaptation of hypertensive transgenic rats (TGR) to changing sodium diets with those of spontaneously hypertensive rats (SHR) and normotensive Sprague Dawley rats (SD). Animals were held in metabolic cages and were exposed to a low sodium diet for nine days (31 umol Na+/g), followed by a high sodium diet for ten days (307 umol Na+/g) and again low sodium diet for nine days. Measured parameters were: systolic blood pressure, body weight, water and food intake, urinary and faecal volume as well as sodium and potassium intake and excretion. All groups reacted adequately to an increased or reduced sodium load with an increase or decrease of urinary sodium excretion. SHR thereby compensated a smaller water intake and urinary volume by a significant increase in urinary salt concentration. Based on the parameters measured we could not find any specific differences between TGR, SHR and SD concerning the sodium excretion capacity. Further in TGR there was no sign of a reduced capacity for sodium excretion under oral sodium load that could be involved in TGR hypertension.