DIFFERENT EFFECTS OF 3 ALDOSTERONE TREATMENTS ON PLASMA-ALDOSTERONE AND SALT INTAKE

Adrenalectomized male rats received a nominal dose of 47.6 mug/day ald osterone for 14 days by daily injections, osmotic minipumps, or contro lled-release pellets. Plasma aldosterone concentrations were barely de tectable (<20 pg/ml) 24 h after rats received aldosterone by injection , remained constant at 200 pg/ml in rats with osmotic minipumps, and d ropped from >500 to 75 pg/ml during the first week after implantation of controlled-release pellets. For the most part, the effects of the d ifferent treatments on NaCl intake were related to their effects on pl asma aldosterone levels according to a U-shaped function. However, NaC l intake was dissociated from plasma aldosterone levels when treatment first began or was discontinued. NaCl intake may be a function of the amount of aldosterone delivered but not necessarily plasma aldosteron e concentration.