Linked Life Data

2566657

Source:http://linkedlifedata.com/resource/pubmed/id/2566657

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
5
pubmed:dateCreated
1989-7-7
pubmed:abstractText
1. Intracellular and extracellular recording techniques were used to study the effects of bath application of 4-aminopyridine (4-AP) on pyramidal cells of the CA1 subfield of rat hippocampal slices maintained in vitro. The concentration of 4-AP used in most experiments was 50 microM. However, similar results were obtained with a concentration ranging from 5 to 100 microM. 2. Following 4-AP application, cells impaled with K-acetate-filled microelectrodes hyperpolarized by an average of 2.6 mV (from -68.7 to -71.3 mV, P less than or equal to 0.01). This change was accompanied by the appearance of high-frequency spontaneous hyperpolarizations. Conversely, when KCl-filled microelectrodes were used, an average depolarization of 5.8 mV [from -73.1 to -67.3 mV, not significant (NS)] associated with the occurrence of repetitive depolarizing potentials was observed. In both cases, these changes were concomitant with a small decrease in membrane input resistance, which was statistically significant only for cells impaled with K-acetate-filled microelectrodes. When synaptic transmission was blocked by tetrodotoxin (TTX), 4-AP induced in cells studied with K-acetate microelectrodes an average depolarization of 2.4 mV (from -62.8 to -60.4 mV, P less than or equal to 0.01) accompanied by a small increase in input resistance (from 32.0 to 35.8 M omega, P less than or equal to 0.05). High-frequency spontaneous potentials failed to occur under these conditions. During 4-AP application, the threshold and the latency of action potentials elicited by a depolarizing current pulse increased in 36% of the neurons studied (n = 14). 3. The amplitude of the stratum (s.) radiatum-induced excitatory postsynaptic potential (EPSP) was augmented by 4-AP. Both the early and late inhibitory postsynaptic potentials (IPSPs) evoked by orthodromic stimuli were also increased in amplitude and duration. In addition, a late (peak latency, 150-600 ms) and long-lasting (duration, 600-1,500 ms) depolarizing potential appeared between the early and the late IPSPs and progressively increased until it partially masked these hyperpolarizations. This long-lasting depolarization (LLD) could also be induced by antidromic stimulation, although in this case it was preceded by an additional, fast-rising, brief depolarization. 4. A similar brief depolarization preceded the orthodromically induced LLD in 69% of the neurons bathed in the presence of 4-AP. The average value of the peak latency of this potential was 62 +/- 27 (SD) ms for orthodromic and 110 +/- 70 ms for antidromic responses.(ABSTRACT TRUNCATED AT 400 WORDS)
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
May
pubmed:issn
0022-3077
pubmed:author
pubmed:issnType
Print
pubmed:volume
61
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
953-70
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1989
pubmed:articleTitle
Effects of low concentrations of 4-aminopyridine on CA1 pyramidal cells of the hippocampus.
pubmed:affiliation
Montreal Neurological Institute, Department of Neurology and Neurosurgery, McGill University, Québec, Canada.
pubmed:publicationType
Journal Article, In Vitro, Research Support, Non-U.S. Gov't