Independent action of antidiuretic hormone, theophylline and cyclic 3′,5′‐adenosine monophosphate on cell membrane permeability in frog skin

Abstract

1. The effects of antidiuretic hormone (ADH), theophylline and cyclic 3′,5′‐adenosine monophosphate (AMP) on membrane potentials in frog skin have been investigated. 2. Membrane potentials across the outer and inner facing membranes were recorded in both normal and current clamped skins. In the latter condition active transport of sodium had been abolished by ouabain or metabolic inhibitors, but ionic gradients were maintained by passing current through the skin from the inside. 3. ADH increases the potential across the outer facing membranes and reduces the skin resistance. The results are consistent with ADH causing an increase in permeability of the outer facing membranes to sodium ions. 4. Theophylline reduces the skin potential by reducing specifically the potential across the outer facing membranes. At the same time the skin resistance is reduced. Theophylline acts by increasing the permeability of the outer facing membranes to chloride ions. 5. Cyclic 3′,5′‐AMP causes a biphasic potential change accompanied by an increase in skin resistance. 6. Metabolic inhibitors block the response of the skin to ADH but not to theophylline. 7. Separate explanations for the increase in sodium transport by ADH, theophylline and cyclic 3′,5′‐AMP are discussed. It is not necessary to involve cyclic AMP in order to explain the effects of either ADH or theophylline.

The effects of anions on sodium transport

“…The values are for curve (a) 5!7 g and for curve (b) 3.0 g. These values may be compared with the thickness increases estimated from weight measurements (8-11 g). In a previous paper (Cuthbert & Painter, 1968b) it was shown that theophylline increased the chloride permeability of the outer facing membranes of frog skin. This conclusion was based on the ability of theophylline to cause a potential fall in choline chloride Ringer, but not in sodium isethionate Ringer.…”

The effects of theophylline and choleragen on sodium and chloride ion movements within isolated rabbit ileum.

“…rabbit ileum, rabbit gall-bladder (Frizzell, Dugas & Schultz, 1975), rat colon (Binder & Rawlins, 1973) 60-90 Q cm2, guinea-pig gallbladder (Saverymuttu & Wood, 1977), and fly salivary gland (Prince & Berridge, 1973) to secretagogues differs from the response of a number of tight epithelia, e.g. rabbit colon (Frizzell, Koch & Schultz, 1976) 220-270 Q cm2, guinea-pig seminal vesicle (Levine, Rinaldo & Schultz, 1976), rabbit cornea (Beitch, Beitch & Zadunaisky, 1974), and frog skin (Cuthbert & Painter, 1968). In the latter group of tight epithelia, the secretagogues have no inhibitory effect on either net or unidirectional transepithelial Na+ fluxes, indeed they may stimulate Na+ absorption in frog skin, whilst causing marked increases in the short-circuit current due to stimulated Cl-secretion.…”

Some aspects of the inhibition of the action of antidiuretic hormone by lithium ions in the rat kidney and bladder of the toad Bufo marinus

“…These changes may affect the action of antidiuretic hormone in the kidney but would not obviously add much towards an explanation of the effects of lithium on the amphibian tissue. The two effects may, of course, be unrelated, as may the effect of cyclic AMP and antidiuretic hormone in the toad bladder (see, for example, Cuthbert & Painter, 1968).…”