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Title: Dopamine receptors of the cockroach salivary gland
Author: Evans, Anthony Mark
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1990
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A study has been made of the secretory response and the electrical reponse (a hyperpolarization followed by a depolarization) mediated by dopamine receptors of the cockroach (Nauphoeta cinerea Olivier) salivary gland in-vitro. Although domperidone did not inhibit the electrical response to dopamine, three other actions were observed: one, post-synaptic, led to the potentiation of the hyperpolarization; this action was shared by (±)sulpiride. A separate post-synaptic action resulted in the inhibition of the depolarizing phase of the response. Finally a pre-synaptic action led to the abolition of the response to nerve stimulation.Effects of the calmodulin antagonists W7 and calmidazolium. In an attempt to investigate the role of calmodulin in stimulus-secretion coupling with the salivary gland, the actions of two calmodulin antagonists, W7 and calmidazolium, were studied. In high concentrations, but within the range in which they are known to inhibit calmodulin, W7 and calmidazolium were found to inhibit dopamine-induced secretion and hyperpolarize the acinar cells. The hyperpolarization was not inhibited by SGH23390, and resulted from an increase in cytosolic free calcium, released from the same source as that accessed by dopamine. Lower concentrations of these two antagonists caused submaximal secretion and potentiated dopamine-induced hyperpolarizations. An interpretation of these results is that calmodulin promotes secretion, and exerts a negative control on cytosolic free calcium by an independent process which can be selectively inhibited.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available