Antidiuretic hormone infusion reduces taurine and NaCl-induced hypernatremia in the rat

Rats drinking taurine and hypertonic saline (T + S) develop severe hypernatremia, but rats drinking either T or S alone do not. One hypothesis for this disruption of homeostasis is that the T + S combination interferes with the actions of antidiuretic hormone (ADH). Rats drinking T + S developed severe hypernatremia (170 mmol/L) by day 8 when infused with distilled water by osmotic minipumps, but maintained plasma sodium below 150 mmol/L when infused with ADH. Cumulative water balance in T + S drinkers receiving ADH was consistently higher than in those not receiving ADH. However the ratio of cumulative sodium balance to cumulative water balance suggests little uniform advantage to rats receiving ADH nor does comparison of urine osmolality in the two groups. Precisely how ADH administration reduces hypernatremia in T + S drinking rats remains unclear, but the hypothesis that T + S interferes with the action of ADH in its regulation of extracellular fluid volume and osmolality remains viable.