G T Eddlestone

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Action potentials and whole cell sodium current were recorded in canine epicardial, midmyocardial, and endocardial myocytes in normal sodium at 37 degrees C. Tetrodotoxin (TTX) reduced the action potential duration of midmyocardial cells to a greater degree than either epicardial or endocardial cells. Whole cell recordings in potassium-free and(More)
The typical burst pattern of electrical activity recorded from beta-cells of mouse islets in the presence of 11.1 mM glucose has been compared from 225 cells in terms of two parameters: relative duration of the active phase and periodicity of the oscillations between active and silent phases. The two parameters show different distributions, Gaussian and(More)
The single-channel recording technique was employed to investigate the mechanism conferring ATP sensitivity to a metabolite-sensitive K channel in insulin-secreting cells. ATP stimulated channel activity in the 0-10 microM range, but depressed it at higher concentrations. In inside-out patches, addition of the cAMP-dependent protein kinase inhibitor (PKI)(More)
The role of Ca2+ in stimulus-response coupling in nonexcitable cells is still not well understood. The Ca2+ responses of individual cells are extremely diverse, often displaying marked oscillations, and almost nothing is known about the specific features of these Ca2+ signals that are important for the functional response of a cell. Using the RBL-2H3(More)
The present experiment was designed to measure the sympathetic firing rate of nerve filaments to interscapular brown adipose tissue in rats with acute and chronic lesions in the ventromedial hypothalamus or paraventricular nucleus. Female rats received injections of kainic acid into either the paraventricular nucleus or the ventromedial hypothalamus. The(More)
K channels in the cell membrane of the insulin-secreting RINm5F cell line were studied using the patch-clamp technique in cell-attached patch mode. With 140 mM K in the pipette, two channels displaying different conductive and kinetics properties were observed. A voltage-independent, inward-rectifying, 55-pS channel was active at rest (no glucose, -70 mV),(More)
1. Membrane potential fluctuations were measured in cells from mouse Islets of Langerhans identified as beta-cells by the characteristic pattern of electrical activity induced by 11 mM-D-glucose. 2. The membrane potential was controlled by adjusting the external potassium concentration, [K+]o, keeping the sum [Na+]o plus [K+]o constant. In the absence of(More)
1. The G protein-mediated coupling of a somatostatin (somatotropin-releasing inhibitory factor; SRIF) receptor to the ATP-dependent K+ channel (K+ATP channel) has been studied in insulin-secreting cells using the patch clamp technique. 2. In excised outside-out patches, the concentration-dependent stimulation of the K+ATP channel by SRIF was biphasic.(More)
Modulation of the Ca- and voltage-dependent K channel--KCa--by receptors coupled to the G proteins G(i)/G(o) and Gs has been studied in insulin-secreting cells using the patch clamp technique. In excised outside-out patches somatostatin (somatotropin-releasing inhibitory factor; SRIF) caused concentration-dependent inhibition of the KCa channel, an effect(More)
The mechanisms underlying mastoparan-induced elevation of the intracellular free calcium concentration ([Ca2+]i) were investigated in the insulin-secreting cell lines RINm5F and HIT. In both cell types, micromolar concentrations of mastoparan induced a prompt increase of [Ca2+]i, measured as an increase in fura-2 fluorescence. This response was dependent on(More)
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