Experimental data obtained on bilayer membranes treated with either of two antibiotics, monazomycin or alamethicin, are presented showing the marked difference in the time course of the rise and subsequent decay of the conductance in response to a positive and negative step of potential established by means of a voltage-clamp feedback circuit. The variation of the conductance with time in these...

1. Whole cell patch clamping of transfected HEK293 cells was used to examine the effects of a pentapeptide (KIFMK) containing the proposed inactivation particle of the Na+ channel on two mutations causing myotonia. One mutation (R1448P) is located in the voltage sensor IV/S4, and the other one (G1306E) near the postulated inactivation gate within the III-IV linker. 2. In the absence of peptide,...

Scanning probe microscopy can be used to probe the internal atomic structure of flat organic molecules. This technique requires an unreactive tip and has, until now, been demonstrated only at liquid helium and liquid nitrogen temperatures. We demonstrate intramolecular and intermolecular force contrast at room temperature on PTCDA molecules adsorbed on a Ag/Si(111)-(√[3]×√[3]) surface. The osci...

Pacemaker (HCN) channels are hyperpolarization-activated and their activity is enhanced by cyclic AMP (CAMP), but whether CAMP-gating is coupled to voltage-gating remains unresolved. With long hyperpolarizations, HCN channels form a secondary open state after the initial opening; this briefly sustains the activation of open channels after a return to a resting voltage. CAMP effects on the forma...

The membrane current activated by fast nicotinic excitation of intact and mature rat sympathetic neurons was studied at 37 degrees C, by using the two-microelectrode voltage-clamp technique. The excitatory postsynaptic current (EPSC) was modeled as the difference between two exponentials. A fast time constant (tau2; mean value 0.57 ms), which proves to be virtually voltage-independent, governs ...

Loss minimization in power system is an important research issue. Transmission line losses in a power system can be minimized by means of reactive power compensation. The continuous demand in electric power system network has caused it to be heavily loaded leading to voltage instability. This phenomenon has also led to voltage profile depreciation below the acceptable secure limit. The signific...

The voltage-clamp technique is applicable only to spherical cells. In nonspherical cells, such as neurons, the membrane potential is not clamped distal to the voltage-clamp electrode. This means that the current recorded by the voltage-clamp electrode is the sum of the local current and of axial currents from locations experiencing different membrane potentials. Furthermore, voltage-gated curre...