Pressure-Dependent Changes in the Release of GABA by Cerebrocortical Synaptosomes
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)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1989
- Accession Number
- ADA214336
Entities
People
- A. J. Dutka
- J. S. Colton
- S. C. Gilman
Organizations
- Naval Medical Research Center