Histological changes in the skin of Rana pipiens produced by metabolic alkalosis

The frog skin has been shown to excrete various electrolytes, the rates can be altered by varying metabolic conditions. The present study was performed to determine if metabolic alkalosis results in histological changes in the skin that are characteristic of this state. Rana pipiens were loaded with NaHCO3 and skin biopsies obtained (I). These biopsies were compared with biopsies from either control, unloaded frogs (II), or from NaCl loaded (III) frogs. In blind studies of microscopic sections, 13 of 15 biopsies of a mixture of I and II were correctly diagnosed, and similarly, 18 of 20 of I and III were correctly diagnosed (P = 0.0037, and 0.0002, respectively). The changes due to NaHCO3 treatment included; (1) an abundance of large euchromatin cells on or near the surface; (2) changes in the basal cell layer with elongation and rotation of the nuclei; (3) lighter cells in the spinosal layer; and, (4) sometimes the skin became thicker. We conclude that metabolic alkalosis results in characteristic histological changes in the skin, and that this is probably related to the ability of the skin to excrete bicarbonate.