Voltage clamp responses of a single excitable fiber were simulated using a core conductor model including a high external resistance (Rs) in series to the fiber membrane to allow for intercellular clefts in a multifiber preparation. In terms of specific resistance, Rs was between 68 and 264 omega cm2. Internal resistivity (Ri) was taken to be zero or 200 omega cm. The aim of the study was to qu...

In our previous report, we showed that L-arginine induced depolarization of smoolh muscle cells of the rat portal vein with an increasecl contraction. To clarify the ionic mechanism of the membrane depolarization, the effect of I.-arginine on the holding current was studied in freshly isolated smooth muscle cells of the rat portal vein. The whole-cell patch-clamp teehnique was used, with the me...

Turtle vomeronasal receptor neurons in slice preparations were studied using the patch-clamp technique in the whole-cell and cell-attached configurations. The mean resting potential was -48, and the response to an injected current step consisted of either a single spike or a train of spikes. An injected current of 3-30 pA was required to depolarize the neuron to spike threshold near -50 mV. Vol...

The effect of low concentrations of barium on the membrane properties of rat neocortical neurons was studied in vitro. Potassium currents were examined using single-electrode current- and voltage-clamp techniques. Neurons responded to bath application of barium (10-100 microM) with a membrane depolarization associated with an increase in input resistance. Under voltage clamp conditions, an inwa...

Asymmetric membrane currents and calcium transients were recorded simultaneously from cut segments of frog skeletal muscle fibers voltage clamped in a double Vaseline-gap chamber in the presence of high concentration of EGTA intracellularly. An inward phase of asymmetric currents following the hump component was observed in all fibers during the depolarization pulse to selected voltages (congru...

Intracellular microelectrode recordings and a two-electrode voltage clamp have been used to characterize the current carried by inward rectifying K+ channels of stomatal guard cells from the broadbean, Vicia faba L. Superficially, the current displayed many features common to inward rectifiers of neuromuscular and egg cell membranes. In millimolar external K+ concentrations (Ko+), it activated ...

The purpose of this study was to investigate the mechanisms responsible for ischemia-induced changes in spontaneous electrical activity. An ischemic-like Tyrode solution (pH 6.6) reversibly depolarized the maximum diastolic potential (MDP) and reduced the action potential (AP) overshoot (OS). We used SNARF-1, which is an indicator of intracellular pH (pH(i)), and perforated-patch techniques to ...

Activation of metabotropic glutamate receptors (mGluRs) has multiple effects on the excitability of pyramidal neurons in rat frontal neocortex. Synaptic transmission and intrinsic excitability are both affected. During studies of the effects of quisqualate on synaptic activity, it was observed that quisqualate also induced a slow inward current. Whole-cell patch clamp recordings were obtained f...