37] Methods for assessing the effects of aldosterone on sodium transport in toad bladder

Abstract

Publisher Summary Aldosterone and other adrcnocortical steroids with mineralocorticoid activity stimulate sodium reabsorption by kidney (the distal convoluted portion of the nephron), intestines, sweat glands, and salivary glands. Because of the difficulty of studying sodium transport and the effect of mineralocorticoids directly in these tissues, simpler sodium transporting tissues, such as frog skin and toad bladder, have been used as model systems. The ease with which sodium transport can be measured in such epithelial membranes is due to the development of the short-circuit current technique by Ussing and Zerahn. The toad bladder is a bilobed saclike tissue, and it has advantages to the investigator in which it may be studied in vitro as a large membrane and because the transporting cells comprise a single cell layer. Thus the asymmetry of the transepithelial sodium transport system may be explored directly.