AJP - Regulatory, Integrative and Comparative Physiology, Vol 253, Issue 1 83-R90, Copyright © 1987 by American Physiological Society
Potassium secretion by nasal salt glands of desert lizard Sauromalus obesus
T. J. Shuttleworth, J. L. Thompson and W. H. Dantzler
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.
