title: Potassium secretion by nasal salt glands of desert lizard Sauromalus obesus.
abstract: Potassium secretion by the nasal salt glands of the herbivorous desert lizard Sauromalus obesus was determined in vivo by a new technique. Intraperitoneal injection of KCl rapidly increased the potassium secretion rate from 0.28 to 15.35 mumol X 100 g-1 X h-1. A second identical intraperitoneal injection, given 15 h after the first, further increased potassium secretion to 50.09 mumol X 100 g-1 X h-1. This was associated with a doubling of plasma K+ concentration and salt gland Na+-K+-adenosinetriphosphatase (ATPase) activity. Neither salt gland weight or residual (Mg2+) ATPase activity were affected. In an isolated perfused head preparation, potassium secretion from the nasal salt glands was stimulated from 0.99 to 10.76 mumol X 100 g-1 X h-1 by methacholine and to 14.68 mumol X 100 g-1 X h-1 by forskolin. In this perfused preparation, simultaneous determination of salt gland perfusion flow (using radiolabeled microspheres) and the rate of potassium secretion revealed that the secreting glands removed 68% of the perfusing potassium ions. Calculations indicated that secretion at the maximal rate observed in vivo would necessitate a fourfold increase in the rate of blood flow to the gland.
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D066298:In Vitro Techniques; D008116:Lizards / Q000097:blood / Q000378:metabolism* / Q000652:urine; D008863:Microspheres; D009297:Nasal Mucosa / Q000378:metabolism*; D009929:Organ Size; D010477:Perfusion; D011188:Potassium / Q000378:metabolism*; D011189:Potassium Chloride / Q000494:pharmacology; D012491:Salt Gland / Q000033:anatomy & histology / Q000201:enzymology / Q000378:metabolism*
chemical_list: D011189:Potassium Chloride; D000251:Adenosine Triphosphatases; D011188:Potassium