Stress response in chronic hypercapnia.

SCHAEFER, KARL E., NANCY MCCABE, AND JUDITH WITHERS. Stress response in chronic hypercajmia. Am. J. Physiol. 214(3) : 543-548. 1968.-Respiratory acidosis induced by prolonged exposure of guinea pigs to 15% COz in 21y0 O2 was compensated after 3 days of exposure. Adrenal cortical response as measured by a rise of blood corticosteroids, adrenal cholesterol depletion, and lymphopenia was limited to the 3-day phase of uncompensated respiratory acidosis. The same was true for adrenal medullary stimulation as indicated by adrenal epinephrine depletion. Free fatty acid levels did not change during the 1 st hr of exposure to 15% COz, but showed a 100% rise after 6 hr of exposure and returned to initial levels with the compensation of the respiratory acidosis. Intermittent daily 8-hr exposure to 15% CO2 for 7 days did neither produce a compensation of the respiratory acidosis nor an abatement of the sympathoadrenal stimulation. Significant changes in body weight consisting in a 10% loss occurred only during the first 2 days of exposure to 15% COZ. Adrenal enlargement and lymphatic involution accompanying the sympathicoadrenal response to respiratory acidosis outlasted the functional changes and were still present after 7 days of exposure to 15% COz.