Oxidative effects of nanosecond pulsed electric field exposure in cells and cell-free media.

Nanosecond pulsed electric field (nsPEF) is a novel modality for permeabilization of membranous structures and intracellular delivery of xenobiotics. We hypothesized that oxidative effects of nsPEF could be a separate primary mechanism responsible for bioeffects. ROS production in cultured cells and media exposed to 300-ns PEF (1-13 kV/cm) was assessed by oxidation of 2',7'-dichlorodihydrofluoresein (H(2)DCF), dihidroethidium (DHE), or Amplex Red.

Cell permeabilization and inhibition of voltage-gated Ca(2+) and Na(+) channel currents by nanosecond pulsed electric field.

Previous studies have found that nanosecond pulsed electric field (nsPEF) exposure causes long-term permeabilization of the cell plasma membrane. In this study, we utilized the whole-cell patch-clamp method to study the nsPEF effect on currents of voltage-gated (VG) Ca(2+) and Na(+) channels (I(Ca) and I(Na)) in cultured GH3 and NG108 cells. We found that a single 300 or 600 ns pulse at or above 1.

Electroporation-induced electrosensitization.

Background: Electroporation is a method of disrupting the integrity of cell membrane by electric pulses (EPs). Electrical modeling is widely employed to explain and study electroporation, but even most advanced models show limited predictive power. No studies have accounted for the biological consequences of electroporation as a factor that alters the cell's susceptibility to forthcoming EPs.

Analysis of plasma membrane integrity by fluorescent detection of Tl(+) uptake.

The exclusion of polar dyes by healthy cells is widely employed as a simple and reliable test for cell membrane integrity. However, commonly used dyes (propidium, Yo-Pro-1, trypan blue) cannot detect membrane defects which are smaller than the dye molecule itself, such as nanopores that form by exposure to ultrashort electric pulses (USEPs). Instead, here we demonstrate that opening of nanopores can be efficiently detected and studied by fluorescent measurement of Tl(+) uptake.

Gadolinium blocks membrane permeabilization induced by nanosecond electric pulses and reduces cell death.

It has been widely accepted that nanosecond electric pulses (nsEP) are distinguished from micro- and millisecond duration pulses by their ability to cause intracellular effects and cell death with reduced effects on the cell plasma membrane. However, we found that nsEP-induced cell death is most likely mediated by the plasma membrane disruption. We showed that nsEP can cause long-lasting (minutes) increase in plasma membrane electrical conductance and disrupt electrolyte balance, followed by water uptake, cell swelling and blebbing.

Lipid nanopores can form a stable, ion channel-like conduction pathway in cell membrane.

Cell permeabilization by electric pulses (EPs), or electroporation, has been well established as a tool to indiscriminately increase membrane flows of water solutes down the concentration and voltage gradients. However, we found that EPs of nanosecond duration (nsEPs) trigger formation of voltage-sensitive and inward-rectifying membrane pores. NsEP-treated cells remain mostly impermeable to propidium, suggesting that the maximum pore size is approximately 1nm.

Acute tolerance to alcohol effects on inhibitory and activational mechanisms of behavioral control.

Objective: Acute alcohol tolerance refers to the observation of reduced impairment at a given blood alcohol concentration (BAC) on the descending versus ascending limb of the blood alcohol curve. Psychomotor performance measures used in human studies of alcohol tolerance provide reliable assessments of tolerance but do not identify specific mechanisms involved in the re-establishment of control, and little is known about how acute tolerance is expressed in terms of changes in fundamental mechanisms that regulate and control behavior. This study examined the expression of acute alcohol tolerance to impaired behavioral control in terms of changes in a drinker's ability to activate and inhibit behavioral responses as BAC ascended and declined following a dose.