Use this URL to cite or link to this record in EThOS:
Title: The effects of caffeine on intracellular calcium in snail neurones (Helix aspersa)
Author: Collins, R.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2000
Availability of Full Text:
Full text unavailable from EThOS.
Please contact the current institution’s library for further details.
I have studied the role of intracellular stores in modulating intracellular calcium using the fluorescent indicator fura-2 in voltage-clamped snail neurones in isolated ganglia. I have used caffeine as an agonist to stimulate release of calcium from the intracellular stores and cyclopiazonic acid (CPA) to prevent the stores refilling. Caffeine application (10mM) resulted in a transient rise in Ca2+ that was followed by an undershoot. To explore the process of the undershoot, intracellular calcium was raised by inhibiting the plasma membrane Ca2+-H+ ATPase (PMCA) using high extracellular pH, vanadate or Eosin B. Inhibiting the PMCA resulted in a raised Ca2+ level and a larger undershoot. The undershoot was abolished in the presence of 50μM CPA. These results are consistent with uptake into stores pump generating the undershoot. Depolarisation of the plasma membrane to 0mV and application of 10 mM caffeine to neurones, both resulted in a calcium transient. An increase in intracellular fura-2 concentration affected the depolarisation and caffeine-induced calcium transients differently. In five out of seven experiments the caffeine-induced calcium transients were reduced to a greater extent than the depolarisation-induced transients. This may be through the calcium buffering action of fura-2 or direct interaction of fura-2 with the ryanodine receptor. Attempts were also made to measure the calcium concentration within the endoplasmic reticulum (ER). The low affinity fluorescent calcium indicator fluo-3ff (AM) was used.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available