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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 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 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 contributions of the 4-aminopyridine (4-AP)-sensitive transient outward potassium conductance (Ito1) and the calcium-activated chloride conductance (ICl(Ca)] to cardiac action potentials were investigated in canine ventricular myocytes. Action potentials or currents were recorded at 37 degrees C using standard whole cell or amphotericin B(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)
Two microelectrodes have been used to measure membrane potentials simultaneously in pairs of mouse pancreatic islet cells. In the presence of glucose at concentrations between 5.6 and 22.2 mM, injection of current i into cell 1 caused a membrane potential change in this cell, V1, and, provided the second microelectrode was less than 35 micron away, in a(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)
The influence of forskolin and 3-iso-butyl-1-methylxanthine (IBMX) on mouse pancreatic beta-cell electrical activity, whole islet cAMP content, and insulin release were investigated. The two drugs potentiated to a similar extent both glucose-stimulated electrical activity and insulin release. In terms of the electrical response, both drugs potentiated the(More)
Insulin secretion from the islets of Langerhans may be initiated or potentiated by increased phospholipase A2 (PLA2) activity. This patch-clamp study of the insulin-secreting HIT tumor cell line assessed whether inhibition of the ATP-sensitive potassium (KATP) channel, which modulates the secretion-associated beta-cell electrical activity, contributes to(More)