Repetitive mechanical responses of the amphibian skin to adrenergic stimulation .
Mechanical responses of the amphibian nerve-skin preparation to adrenergic stimulation were investigated by recording pressure changes at the skin surface with a piezoelectric sensor. When a dilute epinephrine (or norepinephrine) solution was applied to the inner skin surface, repetitive mechanical responses, representing quick swelling of the skin repeating at more or less regular intervals of about 1 min, were frequently observed. In about 10% of the preparations, the skin was found to undergo repetitive quick shrinkage (instead of swelling) under practically indistinguishable experimental conditions. Rapid volume changes occurring in the cytoplasmic gel of the gland cells are considered to be at the base of these repetitive mechanical responses.