Most investigators hold tentatively, to the view of Ussing ('49) and of Engbaek and Hoshiko ('57) that active sodium transport and generation of skin potential in frog skin occur in the "inner epidermis," possibly in the stratum germinativum. This layer is sandwiched between the "outer epidermis" (stratum corneum and stratum granulosum) and the corium. The corium consists of bands of dense and loose connective tissue in which are embedded mucous glands, blood vessels and nerves, and the tela subcutanea. A well defined basement membrane is located between the dermal side of the inner epidermis and the corium. In studies on active ion transport it seems important, therefore, to investigate the characteristics of the diffusion barriers on either side of the region in which active transport takes place. Andersen and Zerahn ('63) have obtained data on the amount of sodium inside and outside the active transport Separate estimations of sodium permeability and diffusion coefficients in epidermis and corium were suggested, when it was found (Skjelkvae et al., '60) that osmotic treatment (soaking) of isolated skin initiates shedding of the epidermis, leaving the corium as "stripped skin." The present study gives the histological changes, recorded in time, and some biochemical data on soaked and stripped skin. Osmotic damage of skin and recovery from it was evaluated by comparison of the appearance and behavior of soaked and stripped skins with that of fresh skins. From sodium22 flux measurements on soaked and stripped skins, average sodium permeability and diffusion coefficients in corium and epidermis were calculated. pool. J. CELL. AND COMP. PHYSIOL., 64: 371-388.Estimations of sodium permeability coefficients in fresh epidermis were also made, based on the observations and measurements just mentioned, on new measurements of sodiumz2 flux in whole fresh skin and on some reasonable assumptions. A simple method was used for measuring the self diffusion coefficient of sodium22 in Ringer-agar gel. The results of the measurements in agar were compared with those obtained in skin. METHODS . Measurement of the diffusion coefficient of NuzZ in Ringer-ugar.The hub ends of two 2 ml hypodermic syringes were cut off and the glass ends of the syringes were ground and polished. Sodium"-Ringer-agar was poured into one of the syringes with the greased plunger sitting near the end of the barrel. A low mount of agar was formed at the glass edge of the syringe. When the agar had stiffened, a clean cut was made with a razor blade through the protruding agar and the glass edge was wiped off. This syringe represented the lower section of the diffusion assembly. The upper syringe section was then fitted to the lower section and held in place by friction tape. Nonradio-active agar of the same batch from which the Na22 agar was prepared, was then poured, at no more than 60°C, into the upper section. Care was taken to make upper and lower agar columns the same length. For protection, the ungreased plunger of the upper syringe section was gently ...

No abstract

No abstract