As in normal behavior, when the head was restrained LIP stimulation evoked eye-only saccades in Listing’s plane, whereas
when the head was not restrained, stimulation evoked saccades with position-dependent torsional components (driving the eye out of Listing’s plane). In behavioral gaze-shifts, the vestibuloocular reflex (VOR) then drives torsion back into Listing’s plane, but in the absence of subsequent head movement the stimulation-induced torsion was “”left hanging”". This suggests that the position-dependent torsional saccade components are preprogrammed, and that the oculomotor system was expecting a head movement command to follow the saccade. These data show that, unlike SEF, FEF, and SC stimulation in nearly identical conditions, LIP stimulation falls to produce normally-coordinated selleck compound eye-head gaze shifts. (C) 2009 IBRO. Published by Elsevier
Ltd. All rights reserved.”
“Dispersion of action potential repolarization is known to be an important arrhythmogenic factor in cardiopathies such as Brugada syndrome. In this work, we analyze the effect of a variation in sodium current (I-Na) inactivation and a heterogeneous rise of transient outward current (I-to) in the probability of reentry in epicardial tissue. We use the Luo-Rudy model of epicardial ventricular action potential to study wave propagation in a one-dimensional fiber. Spatial dispersion in repolarization is introduced by splitting the fiber into zones with different strength of I-to. We then analyze the pro-arrhythmic effect
of a variation in the relaxation time and steady-state of the sodium channel fast inactivating Blebbistatin purchase Temsirolimus supplier gate h. We quantify the probability of reentry measuring the percentage of reexcitations that occurs in 200 beats. We find that, for high stimulation rates, this percentage is negligible, but increases notably for pacing periods above 700ms. Surprisingly, with decreasing I-Na inactivation time, the percentage of reexcitations does not grow monotonically, but presents vulnerable windows, separated by values of the I-Na inactivation speed-up where reexcitation does not occur. By increasing the strength of L-type calcium current I-CaL above a certain threshold, reexcitation disappears. Finally, we show the formation of reentry in stimulated two-dimensional epicardial tissue with modified I-Na kinetics and Ito heterogeneity. Thus, we confirm that while Ito dispersion is necessary for phase-2 reentry, altered sodium inactivation kinetics influences the probability of reexcitation in a highly nonlinear fashion. (C) 2009 Elsevier Ltd. All rights reserved.”
“Previous studies have indicated that the renin-angiotensin-aldosterone system (RAAS) is implicated in the induction of sodium appetite in rats and that different dietary sodium intakes influence the mRNA expression of central and peripheral RAAS components.
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