Fenoterol stimulation of sodium transport in the isolated toad skin: a beta adrenergic effect

1. This work examines the effects of fenoterol on the isolated skin of the Chilean toad Pleurodema thaul. 2. A dose-dependent increase in the potential difference and in the short-circuit current of the skin was found. Furthermore, sodium potential (ENa) and sodium conductance (GNA) also rose. 3. The increase in bioelectric parameters was reversibly blocked by propranolol, was not significantly affected by reserpinization and was not calcium-dependent. 4. The skin response was significantly reduced in the presence of low Na+ in the outer bathing solution. Although the response was also reduced in the presence of isethionate Ringer's in the inner bathing solution, this reduction was less than the decrease in the presence of low Na+. 5. Fenoterol significantly increased toad skin oxygen consumption and net Na+ movement across the skin due to an increase in Na+ flux from mucosa to serosa. 6. These results show that fenoterol enhances active transport across the isolated toad skin probably through beta adrenergic stimulating effects which activate the sodium driving force, sodium conductance and net Na+ transepithelial flux.