Amy Palmer

Dartmouth College

Biophysical Chemistry


1993

Mentor: Dr. Dennis J. Bobilya, Assistant Professor of Animal & Nutritional Sciences

Establishing a Model to Study Zinc Transport Across The Blood-Brain Barrier

The blood-brain barrier, a semipermeable monolayer of brain capillary endothelial cells, regulates the uptake of substances into the central nervous system. The object of this research was to develop a model for studying zinc transport across the blood-brain barrier.

Tests were performed to determine at what point after seeding, the cells formed a monolayer comparable to the in vivo monolayer whichood-brain barrier. serves as the bl In addition, studies were performed to determine the effect of varying environments on the pH of experimental medium.

In order to ensure strict regulation of the factors which might affect Zn transport, these studies employed the use of cultured cells. Capillary endothelial cells were isolated from piglet brain. Cells from passages 3, 4 and 5 were seeded on microporous membranes and the rate of Zn transport and albumin leakage were measured at eight different time points. 65Zn transport was measured by gamma scintillation count and atomic absorption spectroscopy. Albumin leakage was determined by spectrophotometry.

These studies revealed that there was relatively little change in the rate of albumin transport, which serves as an indicator of membrane integrity, between days 4 and 6. This indicates that during this time the monolayer was probably fully formed and in good condition, i.e. the cells were confluent and tight junctions had formed. This would therefore be the ideal time to study Zn transport. The pH studies revealed that it is essential to include NaHC03 in experimental medium. They also indicated that HEPES can help medium resist pH change at varying temperatures.

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