title: Distal tubular tracer microinjection study of renal tubular potassium transport.
abstract: Renal tubular potassium (K) transfer was studied in rats using a tracer microinjection technique in which [14C]inulin and 42K were simultaneously injected into early distal tubules during osmotic diuresis. Experiments were carried out in 1) animals on a control diet, 2) animals in which K secretion had been stimulated (high-K diet + KC1, Na2SO4, Diamox infusions), and 3) animals in which K excretion had been reduced by a low-K or low-Na diet or by amiloride. 42K excretion into the urine coincided closely in time with the excretion pattern of [14C]inulin. Efflux of 42K out of the lumen was stimulated during reduced K secretion along the distal nephron and decreased during enhanced K secretion when small tubular K loads were given. These experiments demonstrate bidirectional K movement across the distal nephron and show that changes in reabsorptive K efflux participate in the regulation of tubular net K movement.
mesh_terms: D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D004032:Diet; D004231:Diuresis; D007444:Inulin / Q000378:metabolism; D007684:Kidney Tubules / Q000378:metabolism*; D007686:Kidney Tubules, Distal / Q000378:metabolism*; D008845:Microinjections; D011188:Potassium / Q000378:metabolism*; D051381:Rats; D012964:Sodium / Q000378:metabolism
chemical_list: D000584:Amiloride; D007444:Inulin; D012964:Sodium; D011188:Potassium