Red blood cell sodium in the DOCA hypertensive pig.

The influence of deoxycorticosterone acetate (DOCA) on the sodium content of the red blood cell was determined in the pig. DOCA (100 mg/kg), impregnated in Silastic, was implanted subcutaneously (s.c.) in six male pigs; seven additional pigs received Silastic implants without the DOCA. Those receiving DOCA had an increase in mean arterial pressure (MAP) that was significant in 48 hours and reached a plateau that was 24 mm Hg greater than that of the controls after 15 days. These animals also developed hypokalemia and polydipsia over approximately the same time course. Red blood cell sodium content increased in DOCA-treated pigs 24 hours after implant (5.57 +/- 0.17 vs 5.23 +/- 0.05, mEq/liter cells). The sodium content continued to rise, reaching a plateau 28% above that of control value by the 5th postimplant day (6.37 +/- 0.40 mEq/liter cells). In vitro tests of possible mechanisms that might have caused the in vivo increase in red blood cell sodium content gave the following results: 1) Incubations of red blood cells in a physiological salt solution (PSS) containing deoxycorticosterone failed to cause an increase in cell sodium content. 2) No ouabain-like factor was demonstrated in plasma from the DOCA hypertensive pigs. 3) An elevation in bicarbonate concentration in the PSS caused an increase in red blood cell sodium content. 4) A decrease in potassium concentration in the PSS also caused an increase in red blood cell sodium content.(ABSTRACT TRUNCATED AT 250 WORDS)