The role of pH and osmolarity in evoking the acetic acid-induced wiping response in a model of nociception in frogs.

Acetic acid applied to the hindlimb of a frog evokes a vigorous wiping of the exposed skin. The aim of this study was to determine if acetic acid evokes this wiping response by decreasing subepidermal pH. Because acetic acid is hyperosmolar, a second aim was to determine if the osmolarity of acetic acid contributed to evoking the wiping response.