Effects of 18-hydroxycorticosterone and of aldosterone on acid-base parameters in the arterial blood of adrenalectomized rats.

Adrenalectomized rats were injected twice with either 2 micrograms aldosterone or 6 micrograms 18-hydroxycorticosterone (18-OH-B) and were then kept either under normal, or high-CO2 respiratory conditions. Arterial blood samples were withdrawn sequentially from T1 (i.e., 70 minutes after the first injection) on, and were then submitted to determinations of pH and PCO2. Bicarbonate levels were calculated from these data. 18-OH-B: 1) increased pH under both conditions; 2) had a tendency to decrease PCO2 in both conditions; the decrease was significant at 130 minutes after injection, under normal conditions; 3) increased CO3H levels at T1 under high-CO2 atmospheres. Aldosterone did not produce changes in pH values, even if injected in doses equimolar to those of 18-OH-B, but showed a tendency--at these higher doses--to decrease PCO2 values.