Accession Number:

ADA214336

Title:

Pressure-Dependent Changes in the Release of GABA by Cerebrocortical Synaptosomes

Descriptive Note:

Corporate Author:

NAVAL MEDICAL RESEARCH INST BETHESDA MD

Report Date:

1989-01-01

Pagination or Media Count:

7.0

Abstract:

Exposure of animals to ambient pressures of 19 ATA and greater results in a disturbance of neurologic function referred to as the high pressure nervous syndrome HPNS. This disorder progresses through a number of symptomatic stages beginning with myoclonic jerks followed by alterations in electroencephalographic EEG activity, tremor and finally convulsions. Previous studies describe a depression in potassium-evoked, calcium-dependent transmitter release from guinea pig cerebrocortical synaptosomes in response to compression to 68 ATA with heliox. The study described in this paper was designed to evaluate whether a similar effect could be detected at lower pressures and to determine whether the effect had an abrupt onset with a fixed response or a progressive response varying over a range of pressures. A typical response to potassium-evoked depolarization was observed at all pressures studied. This consisted of an initial rising phase lasting 2 to 3 min followed by a falling phase. There was a pressure-dependent depression in the absolute amount of transmitter released as well as a depression in the rate of release in the first minute following stimulation. The mean depression in gamma-aminobutyric acid release during the first minute was an average of 15 at 19 ATA, 28 at 37 ATA, 38 at 50 ATA, and 54 at 62 ATA when compared to a 1 ATA control. Keywords High pressure nervous syndrome Gamma-aminobutyric acid Synaptosome Neurotransmitter Pressure Reprints. KT

Subject Categories:

  • Biology
  • Stress Physiology

Distribution Statement:

APPROVED FOR PUBLIC RELEASE