Stop-flow analysis of the influence of pCO₂ on renal tubular transport of K and H

¹ Departments of Medicine and Pharmacology, University of Western Ontario, London, Canada

The stop-flow procedure was used to study the transport of H and K ions in the renal tubule during conditions of high and low pCO₂. The increased rate of K excretion during respiratory alkalosis was due primarily to marked increase of K secretion at a distal site. The interrupted stop flow showed that K reabsorption was decreased at a site just proximal to the secretory area. This made a smaller contribution to the increased K excretion. The reciprocal relationship between tubular transport of K and H was demonstrable. CO₂ tension appeared to influence HCO₃ reabsorption and H secretion in both the distal and proximal tubule, whereas its effect on K transport was confined to the distal tubule. Hypercapnia never completely obliterated the distal secretory site. It is suggested that a pCO₂-dependent H carrier is not shared with K. The increased K secretion of hypocapnia is more likely the result of increased K within the distal tubular cells.

Key Words: hydrogen • potassium • CO₂ tension

Submitted on October 14, 1963