Erythrocyte carbonic anhydrase: a major intracellular enzyme to regulate cellular sodium metabolism in chronic renal failure patients with diabetes and hypertension.

Changes in carbonic anhydrase (CA) activity have been associated with metabolic diseases like diabetes mellitus and hypertension. To explore the exchange of H+ for Na+ and 22Na+, the sodium pool, CA activity and H2O content in erythrocytes from the two groups of diabetic chronic renal failure (CRF) patients with and without hypertension before dialysis were studied. The results were compared with those from the normotensive controls. The CA activity was determined spectrophotometrically, the sodium pool by ouabain insensitive 22Na+ influx and the percent H2O content gravimetrically. The 22Na+ influx in CRF patients with hypertension was significantly higher (p less than 0.025) than in the normotensive CRF patients and the controls. The levels of CA activity (U/min/mL) and the percent H2O content were significantly different in the hypertensive and the normotensive CRF patients from the control group (2.24 +/- 0.69 and 67.11 +/- 1.33, 1.95 +/- 0.63 and 66.43 +/- 1.51, 1.44 +/- 0.07 and 63.61 +/- 1.72, respectively). The present study implies a relationship between the 22Na+ influx and CA activity in CRF patients with hypertension. The variation of CA activity may thus result in changes in H+ production and ultimately in the intracellular Na+ pool.