title: Effects of dDAVP on rat juxtamedullary nephrons: stimulation of medullary K recycling.
abstract: The effects of 1-desamino-8-D-arginine vasopressin (dDAVP) on the handling of water and electrolytes by the juxtamedullary nephrons were studied on rats with reduced circulating levels of antidiuretic hormone (ADH), parathyroid hormone, calcitonin, and glucagon, all of which stimulate the adenylate cyclase system of the thick ascending limb and the distal tubule. In such hormone-deprived rats and in hormone-deprived + dDAVP rats, the concentration of Na, Cl, and total solutes was lower in the ascending than in the descending limbs, whereas the inulin concentration was similar at both sites. dDAVP did not alter the fraction of NaCl remaining in the thin limbs, but tended to reduce that of Mg and Ca. On the other hand, dDAVP significantly increased the fraction of filtered K remaining from 65.8 +/- 5.2 to 107.3 +/- 15.8%. A direct correlation was observed between the fraction of filtered K remaining at the tip of the juxtamedullary loops and the fractional excretion rate of K in urine. Since dDAVP enhances distal K net secretion, as previously shown in our laboratory, these results indicate that the medullary recycling of K from nephron terminal segments to Henle's loop of juxtamedullary nephrons is stimulated by this peptide.
mesh_terms: D000818:Animals; D001127:Arginine Vasopressin / Q000494:pharmacology*; D002712:Chlorides / Q000652:urine; D003894:Deamino Arginine Vasopressin / Q000494:pharmacology*; D005934:Glucagon / Q000037:antagonists & inhibitors; D007677:Kidney Function Tests; D007679:Kidney Medulla / Q000187:drug effects / Q000378:metabolism*; D008138:Loop of Henle / Q000187:drug effects / Q000378:metabolism; D008297:Male; D009318:Natriuresis / Q000187:drug effects*; D009399:Nephrons / Q000187:drug effects / Q000378:metabolism*; D009994:Osmolar Concentration; D011188:Potassium / Q000378:metabolism* / Q000652:urine; D051381:Rats; D011910:Rats, Brattleboro; D012964:Sodium / Q000652:urine; D014462:Ultrafiltration
chemical_list: D002712:Chlorides; D001127:Arginine Vasopressin; D005934:Glucagon; D012964:Sodium; D003894:Deamino Arginine Vasopressin; D011188:Potassium