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Full-Text Articles in Cell Biology

Mechanisms Of Somatostatin-Induced Paradoxical Increase In Insulin Secretion In The Presence Of Arginine Vasopressin In Clonal [Beta]-Cell Hit-T15 , Henrique Cheng Jan 2002

Mechanisms Of Somatostatin-Induced Paradoxical Increase In Insulin Secretion In The Presence Of Arginine Vasopressin In Clonal [Beta]-Cell Hit-T15 , Henrique Cheng

Retrospective Theses and Dissertations

We investigated the mechanism underlying somatostatin-induced increase in [Ca2+]i leading to insulin release in the presence of arginine vasopressin (AVP) in clonal beta-cell HIT-T15. Somatostatin increased [Ca2+]i and insulin release in a biphasic pattern, characterized by a sharp and transient increase followed by a rapid decline to the sub-basal level. Pretreatment with pertussis toxin, which inactivates Gi/Go, abolished the effects of somatostatin. U-73122, an inhibitor of phospholipase C, antagonized somatostatin-induced increase in [Ca2+] i. In Ca2+-free environment, somatostatin still increased [Ca2+]i, whereas depletion of intracellular Ca 2+ stores with thapsigargin, a microsomal Ca2+ ATPase inhibitor ...


Nitric Oxide In Astrocyte-Neuron Signaling , Nianzhen Li Jan 2002

Nitric Oxide In Astrocyte-Neuron Signaling , Nianzhen Li

Retrospective Theses and Dissertations

Astrocytes, a subtype of glial cell, have recently been shown to exhibit Ca2+ elevations in response to neurotransmitters. A Ca 2+ elevation can propagate to adjacent astrocytes as a Ca2+ wave, which allows an astrocyte to communicate with its neighbors. Additionally, glutamate can be released from astrocytes via a Ca2+ -dependent mechanism, thus modulating neuronal activity and synaptic transmission.;In this dissertation, I investigated the roles of another endogenous signal, nitric oxide (NO), in astrocyte-neuron signaling. First I tested if NO is generated during astrocytic Ca2+ signaling by imaging NO in purified murine cortical astrocyte cultures. Physiological concentrations of a ...