THE EFFECT OF TOPICALLY APPLIED SUBSTANCES ON THE BLOOD-BRAIN BARRIER

¹ Laboratory of Neurophysiology, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland

1. The effect was studied of a number of substances, applied to the surface of the cerebral cortex of the cat, on the cortical acidic response to intravenous NaHCO₃. The response was taken to indicate the presence of a blood-brain barrier.

2. A log₁₀ function (log MARR), of the ratio of the test maximum acidic response to the control maximum acidic response, was considered a reliable criterion for a multiple comparison analysis.

3. Substances could be separated into two significant groups:

Group I, which reduced the cortical acidic response and increased the cortical alkaline tendency, was comprised of n-butanol, n-propanol, ethanol, methanol, sodium lauryl sulfate, sodium cholate and hexadecyl trimethyl ammonium bromide.

Group II, without effect on the acidic response, included 0.9% NaCl, distilled water, several metabolic inhibitors, higher molecular weight alcohols, KCl and sodium glycocholate.

4. Sodium glycocholate and p-chloromercuribenzoate did not change the height of the acidic response but did increase the alkaline trend which followed it.

5. Significant effects on the acidic response to NaHCO₃ were not correlated with changes in the d.c. shift.

6. The blood-brain barrier, as defined, was considered broken down only by extreme structural insult, and to be located probably at the pia and/or vascular wall.

This article has been cited by other articles:

				S. I. Rapoport, M. Hori, and I. Klatzo Reversible Osmotic Opening of the Blood-Brain Barrier Science, September 10, 1971; 173(4001): 1026 - 1028. [Abstract] [PDF]