Evidence for reduced presynaptic Ca2+ entry in a lobster neuromuscular junction at high pressure
Autor: | J J Kendig, Y Grossman |
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Rok vydání: | 1990 |
Předmět: |
Time Factors
Physiology Models Neurological Neural Conduction Neuromuscular Junction chemistry.chemical_element In Vitro Techniques Biology Calcium Neurotransmission Synaptic Transmission Neuromuscular junction Membrane Potentials chemistry.chemical_compound Pressure medicine Extracellular Animals Neurotransmitter Synaptic potential Neurotransmitter Agents Long-term potentiation Electric Stimulation Nephropidae Electrophysiology medicine.anatomical_structure chemistry Biophysics Neuroscience Mathematics Research Article |
Zdroj: | The Journal of Physiology. 420:355-364 |
ISSN: | 0022-3751 |
DOI: | 10.1113/jphysiol.1990.sp017917 |
Popis: | 1. Previous studies have shown that hyperbaric pressure depresses synaptic transmission and have suggested that the effect is primarily on transmitter release. The present study analysed the effects of pressure at a crustacean neuromuscular junction. Changes in pressure were compared to changes in extracellular calcium concentration [Ca2+]o with respect to effects on excitatory junction potential (EJP) amplitude, time course, facilitation and potentiation. 2. The effects of 10.1 MPa pressure on EJP amplitude, facilitation and potentiation, but not time course, were mimicked by reducing [Ca2+]o to approximately one-half the normal level. 3. The effects of pressure and the interaction between compression and calcium concentration were analysed in terms of a model of transmitter release. The model assumes that release is dependent on internal calcium concentration, as modulated by both influx and removal processes; that calcium influx is a saturating function of [Ca2+]o; and that release and removal are saturating functions of [Ca2+]i. 4. The results were consistent with the hypothesis that increased pressure acts primarily to reduce calcium influx into the nerve terminal. |
Databáze: | OpenAIRE |
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