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A possible role for intrinsic calcium buffers in the long- term adaptation of crayfish neurons

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dc.contributor.author McMahon, John Christopher. en_US
dc.date.accessioned 2009-07-09T17:31:27Z
dc.date.available 2009-07-09T17:31:27Z
dc.date.issued 1993-07-09T17:31:27Z
dc.identifier.uri http://hdl.handle.net/10464/1754
dc.description.abstract Increasing the impulse activity of neurons in vivo over 3 or more days causes a reduction in transmitter release that persists for days or weeks (eg. Mercier and Atwood, 1989). This effect is usually accompanied by decreased synaptic fatigue. These two changes involve presynaptic mechanisms and indicate "long-term adaptation" (LTA) of nerve terminals. Previous experiments have shown that LTA requires extracellular calcium and protein synthesis (eg. Hong and Lnenicka, Soc. Neurosci. Abstr. 17:1322) and appears to involve communication between the cell body and the nerve terminals. The present study examines the possibility that the reduction in transmitter release is caused by an -increase in the calcium buffering ability within the nerve terminals. It examines the responses of adapted and control nerve terminals to exogenously applied calcium buffer, BAPTA-AM, which decreases transmitter release (Robitialle and Charlton, 1992). If LTA increases intrinsic Ca2+-buffering, the membrane permeant form of BAPTA should have less effect on adapted nerve terminals than on controls. Experiments are performed on the phasic abdominal extensor motor neurons of the crayfish, Procambarns clarkii. BAPTA-AM decreases excitatory postsynaptic potentials (EPSP's) of the phasic extensor muscles in a dosedependent manner between 5 and 50 JLM. LTA is elicited by in vivo stimulation at 2.5 Hz for 2-4 h per day over 3 days, which reduces EPSP's by over 50%. Experiments indicate that BAPTA-AM produces no significant change in EPSP reduction in adapted neurons when compared to controls. These results do not support the hypothesis that increased daily activity alters rapid intrinsic calcium buffers, that are able to reduce transmitter output in the same manner as BAPTA. en_US
dc.language.iso eng en_US
dc.publisher Brock University en_US
dc.subject Neurons. en_US
dc.subject Neuroplasticity. en_US
dc.subject Crayfish--Physiology. en_US
dc.subject Calcium ions. en_US
dc.title A possible role for intrinsic calcium buffers in the long- term adaptation of crayfish neurons en_US
dc.type Electronic Thesis or Dissertation en_US
dc.degree.name M.Sc. Biological Sciences en_US
dc.degree.level Masters en_US
dc.contributor.department Department of Biological Sciences en_US
dc.degree.discipline Faculty of Mathematics and Science en_US


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