The roles of different K+ currents in regulating the generation and waveform of action potentials in Drosophila dorsal longitudinal flight muscles (DLMs) were examined in current-clamp experiments. In response to depolarizing current, DLMs displayed an initial transient rectification of the electronic potential lasting for up to hundreds of milliseconds. This delay in excitation was followed by...

Many important enzyme activities are regulated by Ca2+-dependent interactions with calmodulin (CaM). Some of the most important targets for CaM action are in the nucleus, and Ca2+-dependent CaM translocation into this organelle has been reported. Hormone-evoked cytosolic Ca2+ signals occur physiologically as oscillations, but, so far, oscillations in CaM concentration have not been described. W...

Apical dendrites and somata of layer V pyramidal neurons were recorded with tight-seal patch electrodes in a slice preparation of rat somatosensory cortex. Recording sites were confirmed by measurements of the electrode location and by staining with biocytin. Dendritic recordings were made along the main trunk of the apical dendrite, usually within layer IV, at distances from 100 to 500 microns...

The temporal resolution of carbon-fiber microelectrodes has been exploited to examine the plasticity of quantal secretory events at individual adrenal medullary cells. The size of individual quantal events, monitored by amperometric oxidation of released catecholamines, was found to be dependent on the extracellular ionic composition, the secretagogue, and the order of depolarization delivery. ...

1. The ionic mechanisms of rhythmic burst firing and single spike, tonic discharge were investigated with extracellular and intracellular recordings of single neurones in the guinea-pig nucleus reticularis thalami (NRT) maintained as a slice in vitro. 2. Activation of cortical/thalamic afferents to NRT neurones resulted in a short latency burst of action potentials which could be followed by a ...

Apical dendrites of layer 5 pyramidal cells in a slice preparation of rat sensorimotor cortex were depolarized focally by long-lasting glutamate iontophoresis while recording intracellularly from their soma. In most cells the firing pattern evoked by the smallest dendritic depolarization that evoked spikes consisted of repetitive bursts of action potentials. During larger dendritic depolarizati...

Although cortical dendrites have classically been thought of as passive structures, recent evidence suggests that active conductances, including Ca2+ conductance, are also present in the dendritic membrane. To investigate this, we have recorded intracellularly in slices of rat neocortex bathed in 24 mM tetraethylammonium chloride and 1 microM TTX. Under these conditions, pyramidal neurons gener...

Using high sensitivity fluorescence imaging with shutter speeds approximately 600,000 times faster than those of video frames, we have characterized Ca2+ waves within cells in exquisite detail to reveal Ca2+ signaling routes. Polarized neutrophils exhibited a counterclockwise rotating ryanodine-sensitive juxtamembrane Ca2+ wave during temporal calcium spikes. During stimulation with fMLP, a che...

Calcium is a ubiquitous second messenger used to regulate a wide range of cellular processes. This role in signalling has to be conducted against the rigid homeostatic mechanisms that ensure that the resting level of Ca2+ is kept low (i.e. between 20 and 100 nmol l-1) in order to avoid the cytotoxic effects of a prolonged elevation of [Ca2+]. Cells have evolved a sophisticated signalling system...