Effect of rat cardionatrin I (rat ANF 99–126) on the response of toad skin to angiotensin II

Abstract

The atrial natriuretic peptide cardionatrin I (cardionatrin I is ANF 99–126) was used in studies directed to assess its effects on osmotic water permeability (Posm) and short-circuit current (SCC) in isolated toad skin. Results showed that ANF 99–126 (10−7 M) added to the dermal side of the skin had no effect on basal Posm or SCC. However, ANF 99–126 (3.3 × 10−8 M) was able to produce a 50% reversible inhibition of the maximal Posm response to angiotensin II (AH) (3.2 × 10−8 M). These effects were seen when the skins were preincubated with ANF 99–126 for 10 min or less before the addition of AII Longer preincubation appeared to inactivate ANF 99–126 through proteolysis. ANF 99–126 (10−7 M) failed to inhibit the SCC response to AII (10−5 M) in toad skin. These results are compatible with a modulatory function for ANF on several systems including those involved in the regulation of extracellular fluid volume.Key words: atrial natriuretic factor, natriuretic peptides, epithelial transport.