The effects of aneurysmal subarachnoid hemorrhage on cerebral vessel diameter and flow velocity.

Background: Transcranial Doppler flow velocity is used to monitor for cerebral vasospasm following aneurysmal subarachnoid hemorrhage. Generally, blood flow velocities appear inversely related to the square of vessel diameter representing local fluid dynamics. However, studies of flow velocity-diameter relationships are few, and may identify vessels for which diameter changes are better correlated with Doppler velocity.

Psychophysiological Stress Indicators of Heart Rate Variability and Electrodermal Activity With Application in Healthcare Simulation Research.

Psychological stress arises from a stressor placed on an individual that leads to both emotional and physiological responses. The latter is referred to as psychophysiological stress. Healthcare simulation provides a platform to investigate stress psychobiology and its effects on learning and performance.

Isoflurane modulates activation and inactivation gating of the prokaryotic Na channel NaChBac.

Voltage-gated Na channels (Na) have emerged as important presynaptic targets for volatile anesthetic (VA) effects on synaptic transmission. However, the detailed biophysical mechanisms by which VAs modulate Na function remain unclear. VAs alter macroscopic activation and inactivation of the prokaryotic Na channel, NaChBac, which provides a useful structural and functional model of mammalian Na Here, we study the effects of the common general anesthetic isoflurane on NaChBac function by analyzing macroscopic Na currents () in wild-type (WT) channels and mutants with impaired (G229A) or enhanced (G219A) inactivation.

Fast-onset lidocaine block of rat NaV1.4 channels suggests involvement of a second high-affinity open state.

Local anesthetics (LAs) block resting, open, and inactivated states of voltage-gated Na(+) channels where inactivated states are thought to bind with highest affinity. However, reports of fast-onset block occurring over milliseconds hint at high-affinity block of open channels. Movement of voltage-sensor domain IV-segment 4 (DIVS4) has been associated with high affinity LA block termed voltage-sensor block (VSB) that also leads to a second open state.

Pentobarbital produces activation and block of {alpha}1{beta}2{gamma}2S GABAA receptors in rapidly perfused whole cells and membrane patches: divergent results can be explained by pharmacokinetics.

Millimolar concentrations of the barbiturate pentobarbital (PB) activate gamma-aminobutyric acid (GABA) type A receptors (GABARs) and cause blockade reported by a paradoxical current increase or "tail" upon washout. To explore the mechanism of blockade, we investigated PB-triggered currents of recombinant alpha(1)beta(2)gamma(2S) GABARs in whole cells and outside-out membrane patches using rapid perfusion. Whole cell currents showed characteristic bell-shaped concentration dependence where high concentrations triggered tail currents with peak amplitudes similar to those during PB application.

Halothane inhibition of recombinant cardiac L-type Ca2+ channels expressed in HEK-293 cells.

Background: Volatile anesthetics depress cardiac contractility, which involves inhibition of cardiac L-type calcium channels. To explore the role of voltage-dependent inactivation, the authors analyzed halothane effects on recombinant cardiac L-type calcium channels (alpha1Cbeta2a and alpha1Cbeta2aalpha2/delta1), which differ by the alpha2/delta1 subunit and consequently voltage-dependent inactivation.

Methods: HEK-293 cells were transiently cotransfected with complementary DNAs encoding alpha1C tagged with green fluorescent protein and beta2a, with and without alpha2/delta1.