To investigate the underlying ionic mechanism of the late plateau phase of the action potential in rabbit atrium the whole-cell patch-clamp tech­ nique with intracellular perfusion was used. We recorded the inward current during repolarizations following a brief 2 ms depolarizing pulse to +40 mV from a holding potential of between —70 and —80 mV. The development of this current coincides with t...

Electrical and mechanical responses of frog atrial trabeculae were studied simultaneously using the double-sucrose gap method. Action potentials and twitch tension could be successively generated in fibers in which the slow inward calcium channel current was not observed. As a rule, this could be obtained in the course of a long experiment (3 to 4 hours). Peak tension was shown to increase mono...

Voltage-dependent Na and Ca inward currents underlying the action potential in cultured embryonic ganglion cells of the leech Hirudo medicinalis have been investigated using the gigaseal whole-cell current or voltage-clamp technique. Dissociated ganglion cells were isolated from 7to 14-day-old embryos, and maintained in primary culture for up to 5 days. More than 95 % of the cultured cells had ...

The inward rectifier current generated by Kir2.1 ion channel proteins is primarily responsible for the stable resting membrane potential in various excitable cell types, like neurons and myocytes. Tight regulation of Kir2.1 functioning prevents premature action potential formation and ensures optimal repolarization times. While Kir2.1 forward trafficking has been addressed in a number of studie...

Membrane currents activated by bradykinin (500 nM) and by extracellular ATP (50 microM) were studied in voltage-clamped, NGF-treated rat pheochromocytoma (PC12) cells. Under quasiphysiological ionic conditions, both substances caused an outward current due to opening of Ca(2+)-activated K+ channels. Bradykinin caused an additional inward current that could be studied after blockade by internal ...

Regenerative inward currents help produce slow oscillations through a negative-slope conductance region of their current-voltage relationship that is well approximated by a linear negative conductance. We used dynamic-clamp injections of a linear current with such conductance, INL, to explore why some neurons can generate intrinsic slow oscillations whereas others cannot. We addressed this ques...

In atrial and ventricular cells from hearts of hatched chicks, acetylcholine reduced the overshoot and the duration of action potentials recorded in normal Tyrode's solution (5.4 ITIM K). This effect of acetylcholine is attributed to inhibition of the slow inward current-dependent portion of the action potential because acetylcholine reduced the overshoot, rate of rise, and duration of the Ca/N...

Voltage clamp currents from medium sized ganglion cells of Helix pomatia have a fast transient outward current component in addition to the usually observed inward and outward currents. This component is inactivated at normal resting potential. The current, which is carried by K+ ions, may surpass leakage currents by a factor of 100 after inactivation has been removed by hyperpolarizing conditi...