Exp. Eyt- Res. (1981) 32. 673479 Ionic and Water Transference Numbers of Descemet’s Membrane of the Bovine Cornea ATLE LYSLO, SIGMUND KVERNES Department of Ophthalmology, Faculty of fiZedicine, University of Trondheim, 7000 Trondheim, Norway AND SIGNE KJELSTRUP RATKJE Laboratory of Physicul Chemistry, The Norwegian Institute of Technology, 7034 Trondhedm, Norway (Received 7 May 1980, New York) Transport properties of Descemet’s membrane (DM) from bovine corneas have been studied in the following cell : MCI,, C, 1 j> MCI,. C* Buffer pH = 7.3 \ DM) Buffer pH = 7.3 ML+ are metals Li+ to Rb+, Mg *+ to Sr*+, La3+ and Ce3+. E.m.f. measurements for gradients (I1 :C, = 2 : 1 yield cation transference numbers, tMz+ decreasing in value with z. Changes in pH or temperature have little effect ant,, + Streaming potential measurements give water transference numbers, varying dramatically in magnitude with concentration and type of ion present. The data show that Descemet’s membrane has no ion selectivity for monovalent salts. For di- and trivalent salts DM behaves as an ion-exchange membrane with weak preference for anions. The water transfer is in the direction of the cation transfer, and the results arc similar to those reported for porous inorganic membranes. Key u~ds: Descemet’s membrane; ionic transport; water transport: e.m.f. : streaming potentials. 1. Introduction Basement membranes give mechanical support to endothelial cell walls. They are regular collageneous structures with large pores (see Kefalides, 1973 for a general review). Apart from a filtering action, the membrane has been considered as inert, making no restrictions on transport to and from the stroma. The endothelial cells of cornea are believed to control the water cvntents of strvma. and to actively regulate the transport of at least some ions to the interior of the cornea (Maurice, 1971: Fischharg, 1973; Barfort and Maurice, 1974: Hodson and Miller, 1976). A systematic study of cornea1 water and ionic transport should include an investigation of the transport properties of the basement membrane as well. Any selective function of Descemet’s Membrane can then be taken into account when the overall transport is considered. In this paper we propose that, the membrane has ion exchange properties under certain conditions. 2. Methods Electrical transport properties of DM were studied mainly in the following cell MCI,, C, Buffer pH = 7.3 i I DM MCI,. C, Buffer pH = 7.3 ~14.483~/~1/060673+07 SOi.OO/O 0 1981 Academic Press Inc. (London) Limited 673