Objective: Transmembrane resistance is a measure of ionic permeability. The occurrence of ionic permeability on the leptomeningeal tissue may suggest its contribution to the cerebrospinal fluid turnover. This property will support the background for a new in vitro model for the study of subarachnoid physiology. The aim of this study is to identify the occurrence and mean value of transmembrane resistance of leptomeninges in sheep at the basal state.
Methods: Cranial leptomeningeal tissues from 26 adult sheep were isolated. Electrophysiological measurements were performed with the Ussing system. Histological samples of leptomeningeal tissue were prepared under light microscopy and hematoxylin-eosin staining.
Results: The mean transmembrane resistance of the leptomeninges in sheep was found to be 11.38 +/- 1.28 Omega cm(2). The histological preparations revealed the homology with the leptomeninges of humans under light microscopy.
Discussion: Leptomeningeal tissue demonstrates ionic permeability as it was indicated by the measured transmembrane resistance. The low transmembrane resistance observed is comparable to a 'leaky' epithelium. The observation of transmembrane resistance might reflect a mesothelial type of activity. This novel property of leptomeninges may be involved in cerebrospinal fluid turnover.