Talk abstract:

Mathematical Models of Corticotroph Cells

David J.N. Wall
Biomathematics Research Centre
Department of Mathematics and Statistics
University of Canterbury
Private Bag 4800, Christchurch
New Zealand
D.Wall@math.canterbury.ac.nz

Pituitary corticotroph cells generate repetitive action potentials and associated Ca²⁺ transients in response to the agonist corticotropin releasing hormone (CRH). There is indirect evidence suggesting that the agonist, by way of complex intracellular mechanisms, modulates the voltage sensitivity of the L-type a²⁺ discuss some of the Hodgkin-Huxley type models we have constructed of this process, which have indicated that an increase in the L-type Ca²⁺ current is sufficient to generate repetitive action potentials. In particular we discuss the effects of including Ca²⁺ transport between cytosolic and endoplasmic compartments, and the spatial variation in our description of the endoplasmic reticulum (ER) and cytosolic [ Ca²⁺]. We have found firstly that this [Ca²⁺] spatial variation did not significantly affect the generation of action potentials, and secondly that a gradual increase in the ER Ca²⁺ during repetitive action potential activity can ultimately feed back sufficient Ca²⁺ into the cytosol to eliminate action potentials. We discuss ways in which cells might regulate their intracellular [ Ca²⁺] dynamics to avoid such an effect. We also investigate the bursting type behaviour inherent in the model.

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1998-1999 Mathematics in Biology