- Library Home /
- Search Collections /
- Open Collections /
- Browse Collections /
- UBC Theses and Dissertations /
- Studies on the effects of hemoglobin on synaptic transmission...
Open Collections
UBC Theses and Dissertations
UBC Theses and Dissertations
Studies on the effects of hemoglobin on synaptic transmission in the hippocampus Yip, Samuel
Abstract
During head injuries and hemorrhagic stroke, blood is released into the extravascular space. The pooled blood remains in the intracranial cavity for a prolonged period of time. During this time, it has been shown that the pooled erythrocytes get lysed and hemoglobin is released into the intracranial cavities. Since clearance of hemoglobin is slow, neurons may be exposed to hemoglobin and/or its breakdown products, hemin and iron, for long periods of time. It is, therefore, important to understand the effects of hemoglobin and its breakdown products on synaptic transmission. In this study, the electrophysiological actions of these agents on synaptic transmission in rat hippocampal CA1 pyramidal neurons were studied using extracellular field- and whole cell patch-recordings. It was found that commercially available hemoglobin samples produce inconsistent effects on synaptic transmission in hippocampal slices. The commercial hemoglobin which reversibly depressed synaptic transmission in CA1 neurons, was found to be contaminated with ammonium and bisulfate. These agents may be responsible for the observed synaptic depression. Since commercially available hemoglobin contains both methemoglobin and reduced-hemoglobin, the effects of these compounds were studied on synaptic transmission. Methemoglobin had no significant effect on synaptic transmission. Although reduced-hemoglobin, prepared with a method described by Martin et al. (1985), produced a significant reversible depression of synaptic transients, the effects were actually due to the bisulfite that was introduced by the reducing procedure. Unlike hemoglobin, breakdown products of hemoglobin, ferrous chloride and hemin, produced a significant irreversible depression of field excitatory postsynaptic potentials. The importance of these effects of hemoglobin breakdown products in understanding neurological complications that follow head-injuries and hemorrhagic stroke awaits further investigation.
Item Metadata
Title |
Studies on the effects of hemoglobin on synaptic transmission in the hippocampus
|
Creator | |
Publisher |
University of British Columbia
|
Date Issued |
2000
|
Description |
During head injuries and hemorrhagic stroke, blood is released into the
extravascular space. The pooled blood remains in the intracranial cavity for a
prolonged period of time. During this time, it has been shown that the pooled
erythrocytes get lysed and hemoglobin is released into the intracranial cavities.
Since clearance of hemoglobin is slow, neurons may be exposed to hemoglobin
and/or its breakdown products, hemin and iron, for long periods of time. It is,
therefore, important to understand the effects of hemoglobin and its breakdown
products on synaptic transmission.
In this study, the electrophysiological actions of these agents on synaptic
transmission in rat hippocampal CA1 pyramidal neurons were studied using
extracellular field- and whole cell patch-recordings. It was found that
commercially available hemoglobin samples produce inconsistent effects on
synaptic transmission in hippocampal slices. The commercial hemoglobin which
reversibly depressed synaptic transmission in CA1 neurons, was found to be
contaminated with ammonium and bisulfate. These agents may be responsible
for the observed synaptic depression.
Since commercially available hemoglobin contains both methemoglobin
and reduced-hemoglobin, the effects of these compounds were studied on
synaptic transmission. Methemoglobin had no significant effect on synaptic
transmission. Although reduced-hemoglobin, prepared with a method described
by Martin et al. (1985), produced a significant reversible depression of synaptic
transients, the effects were actually due to the bisulfite that was introduced by the
reducing procedure.
Unlike hemoglobin, breakdown products of hemoglobin, ferrous chloride and
hemin, produced a significant irreversible depression of field excitatory
postsynaptic potentials. The importance of these effects of hemoglobin
breakdown products in understanding neurological complications that follow
head-injuries and hemorrhagic stroke awaits further investigation.
|
Extent |
10055366 bytes
|
Genre | |
Type | |
File Format |
application/pdf
|
Language |
eng
|
Date Available |
2009-07-20
|
Provider |
Vancouver : University of British Columbia Library
|
Rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
|
DOI |
10.14288/1.0099514
|
URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
|
Graduation Date |
2000-05
|
Campus | |
Scholarly Level |
Graduate
|
Aggregated Source Repository |
DSpace
|
Item Media
Item Citations and Data
Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.