The actions of N-ethylmaleimide (NEM), a sulfhydryl alkylating agent, on G-protein-mediated inhibition of N-type Ca2+ channels in adult rat superior cervical ganglion (SCG) neurons were studied using whole-cell voltage clamp. In SCG neurons, inhibition of ICa occurs by at least three separable pathways: one pertussis toxin (PTX) sensitive and voltage dependent, and two PTX insensitive and volta...

We have attempted to suppress voltage-dependent conductances in hippocampal neurons by introducing various intracellular agents. Voltage-clamp studies were carried out using acutely dissociated hippocampal neurons from adult guinea pigs. Synaptic events were examined using intracellular recordings in the slice preparation. Sodium conductance was suppressed when the quaternary lidocaine derivati...

The simplest cellular model for classical conditioning in the nudibranch mollusk, Hermissenda crassicornis, involves the presynaptic hair cells and postsynaptic photoreceptors. Whereas the cellular mechanisms for postsynaptic photoreceptors have been studied extensively, the presynaptic mechanisms remain uncertain. Here, we determined the phenotype of the voltage-dependent Ca(2+) current in the...

1. The effects of the cardioactive peptide FMRFamide were tested on enzymatically dissociated muscle cells isolated from hearts of the leech. These cells were normally quiescent, with resting potentials near -60 mV. 2. Superfusion of FMRFamide induced a strong depolarization in isolated heart cells (e.g., >40 mV with 10v6 M FMRFamide). The depolarization was maintained in the continued presence...

Healthy bullfrog sympathetic ganglion cells often show a two-component afterhyperpolarization (AHP). Both components can be reduced or abolished by adding Ca-channel blockers or by removing external Ca. Application of a single electrode "hybrid clamp"--i.e., switching from current- to voltage-clamp at the peak of the AHP, reveals that the slow AHP component is generated by a small, slow, monoto...

The electrophysiological properties of cultured giant interneurons isolated from the terminal ganglion of adult crickets (Gryllus bimaculatus) were investigated using whole-cell patch-clamp techniques. To allow for unequivocal identification of these interneurons in cell culture, a protocol for fast and selective labeling of their cell bodies was established. Prior to cell dissociation, the gia...

Insulin regulates cardiac metabolism and function by targeting metabolic proteins or voltage-gated ion channels. This study provides evidence for a novel, voltage-dependent, nonselective cation channel (NSCC) in the heart. Under voltage clamp at 37 degrees C and with major known conductances blocked, insulin (1 nmol/L to 1 micromol/L) activated an outwardly rectifying current (Iinsulin) in guin...

Instantaneous K channel current-voltage (I-V) relations were determined by using internally perfused squid axons. When K was the only internal cation, the I-V relation was linear for outward currents at membrane potentials up to +240 mV inside. With 25-200 mM Na plus 300 mM K in the internal solution, an N-shaped I-V curve was seen. Voltage-dependent blocking of the K channels by Na produces a ...

We have previously shown that metabotropic glutamate receptor (mGluR) activation can attenuate N-methyl-d-aspartate (NMDA)-induced excitotoxic injury in the neostriatum both in vivo and in vitro. Our earlier studies made use of the non-subtype selective mGluR agonist 1-amino-cyclopentane-1,3-dicarboxylic acid (tACPD). In the present study, we extended these observations by identifying the subty...

Modulation of high-conductance chloride channels by eicosanoids, stilbene derivatives and Zn2+ ions was studied in cultured myoblasts (L6 rat muscle cell line) in excised and cell-attached membrane patches using a conventional patch clamp method. Arachidonic acid (AA) blocked the channel at concentrations 1-50 mumol/l from the internal side of the membrane in excised (inside out) patches with a...