Application of the metabotropic glutamate receptor (mGluR) agonist (1S, 3R)-1-aminocyclopentane-1,3-dicarboxylic acid (ACPD) or the selective group I mGluR agonist (S)-3,5-dihydroxyphenylglycine (DHPG) depolarized both CA3 and CA1 pyramidal cells in guinea pig hippocampal slices. Simultaneous recordings of voltage and intracellular Ca2+ levels revealed that the depolarization was accompanied by...

To investigate the mechanisms that account for the voltage dependence of fertilization and provide an electrical block to polyspermy, we studied cross-fertilizations between three species of amphibians having different degrees of voltage dependence. Anurans, such as the toad Bufo japonicus, as well as the primitive urodele Hynobius nebulosus, have voltage-dependent fertilization; other urodeles...

The inward-rectifying K+ current (IK1) in cat ventricular myocytes, like inward-rectifying K+ currents in many other preparations, exhibited a negative slope conductance region at hyperpolarized membrane potentials that was time-dependent. This was evident as an inactivation of inward current elicited by hyperpolarizing voltage-clamp pulses resulting in a negative slope region of the steady-sta...

The liverwort Conocephalum conicum with anion channels blocked by anthracene-9-carboxylic acid (A-9-C) and potassium channels blocked by tetraethylammonium (TEA) generates dose-dependent responses to illumination further called voltage transients (VTs). Unlike the action potentials in untreated Conocephalum thalli, VTs do not propagate and cannot be evoked by electrical stimuli. Except A-9-C, t...

The pore-forming subunits of canonical voltage-gated sodium and calcium channels are encoded by four repeated domains of six-transmembrane (6TM) segments. We expressed and characterized a bacterial ion channel (NaChBac) from Bacillus halodurans that is encoded by one 6TM segment. The sequence, especially in the pore region, is similar to that of voltage-gated calcium channels. The expressed cha...

We have studied the contribution of P-type voltage-dependent Ca2+ channels to both catacholamine (CA) and ATP secretion from bovine chromaffin cells induced by high K+ or nicotine using omega-agatoxin IVA, a selective blocker of P-type voltage-dependent Ca2+ channels. We found that high K+ (75 mM) induced the release of about 13% of norepinephrine, 5% epinephrine and 11% ATP, and that omega-aga...

Polyamines block the retinal cyclic nucleotide-gated channel from both the intracellular and extracellular sides. The voltage-dependent mechanism by which intracellular polyamines inhibit the channel current is complex: as membrane voltage is increased in the presence of polyamines, current inhibition is not monotonic, but exhibits a pronounced damped undulation. To understand the blocking mech...

Previous studies have shown that symmetric tetraalkylammonium ions affect, in a voltage-dependent manner, the conductance of membranes containing many channels formed by the PA65 fragment of anthrax toxin. In this paper we analyze this phenomenon at the single-channel level for tetrabutylammonium ion (Bu4N+). We find that Bu4N+ induces a flickery block of the PA65 channel when present on either...

AIM To investigate the mechanism of agmatine by observing the effect of agmatine on the voltage-gated channels in rat hippocampal neurons. METHODS The whole-cell patch recording technique was performed to record the voltage-gated potassium, sodium, and calcium currents in cultured rat hippocampus. Agmatine was applied directly to the single neuron using a pressure injector with microtubules. ...

Outer hair cells (OHC) from the organ of Corti are capable of fast voltage-induced length changes (Santos-Sacchi and Dilger, 1988), suggesting that an associated voltage sensor should reside in the OHC plasma membrane. Voltage-dependent mechanical responses and nonlinear charge movement of isolated OHCs from the guinea pig were analyzed using the whole-cell voltage-clamp technique. Ionic curren...