Altered erythrocyte transmembrane transport of sodium and potassium in patients with conventional or reservoir ileostomy

Abstract

Brevinge H, Herlitz H, Jonsson O. Altered erythrocyte transmembrane transport of sodium and potassium in patients with conventional or reservoir ileostomy. Scand J Clin Lab Invest 1993; 53: 765-772.

After proctocolectomy, the loss of the colonic absorptive capacity of sodium is compensated for by increased small intestine sodium absorption and renal conservation of Na by enhanced tubular reabsorption. These processes entail increased cellular sodium transport in the enterocytes and in the renal tubular cells.

In order to evaluate if there is a general increase in cellular transport of Na after proctocolectomy for inflammatory bowel diseases erythrocyte Na and K contents and the transmembrane Na fluxes were determined in 35 patients with conventional ileostomy, 23 of which were reinvestigated after conversion to continent reservoir ileostomy. A selected group of another 12 patients having high output from their reservoir ileostomy and low urinary Na were studied concomitantly and 33 healthy subjects served as controls. The intracellular Na content did not differ between the groups while the intracellular K levels were higher in patients with conventional or continent ileostomy compared to controls. In addition, the Na influx and the efflux rate constant of Na were both increased after conversion to reservoir ileostomy. Na influx correlated positively with intake and urinary excretion of Na in conventional ileostomy patients. The results suggest that patients with ileostomy have an increased cellular K uptake and that construction of a reservoir ileostomy further alters cell cation transport by increasing the transmembrane Na turnover.

Key Words:

• ileal reservoir
• sodium-potassium pump