Effect of diet-induced sodium deficiency on normal and compensatory growth of the lung in young rats.

Sodium deficiency is associated with decreased muscle growth and protein synthesis. We investigated the influence of diet-induced sodium deficiency on the rate and extent of compensatory growth of the right lung after left pneumonectomy in young rats of 83 +/- 1 g body weight. Starting 1 wk before surgery, all rats were fed a diet deficient only in sodium (2-9 mumol Na+/g of food) ad libitum. Sodium-deficient rats were supplied with distilled water, whereas sodium-replete controls were supplied water containing 37 mM NaCl. After 7 d on the experimental diets, both groups were divided and subjected either to sham thoracotomy (Sham) or to left pneumonectomy (PNX). Somatic growth and both normal and compensatory growth of the lungs were assessed 3, 4, and 7 d later. Sodium-deficient animals grew more slowly than control animals. In control PNX rats, right lung weight to body weight ratio (LW/BW) increased to equal that of the combined LW/BW in control Shams by postoperative d 4, and remained at the Sham combined LW/BW value on postoperative d 7. Compensatory lung growth was less rapid in sodium-deficient PNX animals. At postoperative d 4, right LW/BW was low relative to combined LW/BW of sodium-deficient Shams. This ratio approached but did not reach the sodium-deficient Sham combined LW/BW value by d 7. Sodium deficiency thus reduced the rate of compensatory growth of the right lung.(ABSTRACT TRUNCATED AT 250 WORDS)