Search results for "Ion Channels"
showing 7 items of 137 documents
Computational methods and theory for ion channel research
2022
Ion channels are fundamental biological devices that act as gates in order to ensure selective ion transport across cellular membranes; their operation constitutes the molecular mechanism through which basic biological functions, such as nerve signal transmission and muscle contraction, are carried out. Here, we review recent results in the field of computational research on ion channels, covering theoretical advances, state-of-the-art simulation approaches, and frontline modeling techniques. We also report on few selected applications of continuum and atomistic methods to characterize the mechanisms of permeation, selectivity, and gating in biological and model channels.
'TRPing' synaptic ribbon function in the rat pineal gland: neuroendocrine regulation involves the capsaicin receptor TRPV1.
2009
Synaptic ribbons (SRs) are presynaptic structures thought to regulate and facilitate multivesicular release. In the pineal gland, they display a circadian rhythm with higher levels at night paralleling melatonin synthesis. To gain more insight into the processes involved and the possible functions of these structures, a series of experiments were conducted in rodents. We studied the regional distribution of a molecular marker of pineal SRs, the kinesin motor KIF3A in the gland. Respective immunoreactivity was abundant in central regions of the gland where sympathetic fibers were less dense, and vice versa, revealing that intercellular communication between adjacent pinealocytes is enhanced …
Interaction of glutamic-acid-rich proteins with the cGMP signalling pathway in rod photoreceptors.
1999
The assembly of signalling molecules into macromolecular complexes (transducisomes) provides specificity, sensitivity and speed in intracellular signalling pathways. Rod photoreceptors in the eye contain an unusual set of glutamic-acid-rich proteins (GARPs) of unknown function. GARPs exist as two soluble forms, GARP1 and GARP2, and as a large cytoplasmic domain (GARP' part) of the beta-subunit of the cyclic GMP-gated channel. Here we identify GARPs as multivalent proteins that interact with the key players of cGMP signalling, phosphodiesterase and guanylate cyclase, and with a retina-specific ATP-binding cassette transporter (ABCR), through four, short, repetitive sequences. In electron mic…
The identification of peroxisome proliferator-activated receptor alpha-independent effects of oleoylethanolamide on intestinal transit in mice
2009
Oleoylethanolamide (OEA) is an endogenous lipid produced in the intestine that mediates satiety by activation of peroxisome proliferator-activated receptor alpha (PPARalpha). OEA inhibits gastric emptying and intestinal motility, but the mechanism of action remains to be determined. We investigated whether OEA inhibits intestinal motility by activation of PPARalpha. PPARalpha immunoreactivity was examined in whole mount preparations of mouse gastrointestinal (GI) tract. The effect of OEA on motility was assessed in wildtype, PPARalpha, cannabinoid CB(1) receptor and CB(2) receptor gene-deficient mice and in a model of accelerated GI transit. In addition, the effect of OEA on motility was as…
Cardiac pacemaker function of HCN4 channels in mice is confined to embryonic development and requires cyclic AMP.
2008
Important targets for cAMP signalling in the heart are hyperpolarization-activated and cyclic nucleotide-gated (HCN) channels that underlie the depolarizing 'pacemaker' current, I(f). We studied the role of I(f) in mice, in which binding of cAMP to HCN4 channels was abolished by a single amino-acid exchange (R669Q). Homozygous HCN4(R669Q/R669Q) mice die during embryonic development. Prior to E12, homozygous and heterozygous embryos display reduced heart rates and show no or attenuated responses to catecholaminergic stimulation. Adult heterozygous mice display normal heart rates at rest and during exercise. However, following beta-adrenergic stimulation, hearts exhibit pauses and sino-atrial…
Asymmetric effects of monetary policy shocks across US states
2019
This paper provides new empirical evidence of the asymmetric effects of monetary policy shocks across regions. Using a measure of unanticipated changes in the Fed's policy rates over the period 1969Q3–2008Q4 and a local projection method extended to account for spatial effects, we find that monetary policy tightening leads to a long-lasting decrease in states' real personal income, with asymmetric effects across states that are amplified by spatial spillovers. The paper then investigates the role played by several transmission channels finding larger contractionary effects of monetary policy tightening in states with higher manufacturing share, smaller firms, smaller banks and higher house …
Sparsity-aware multiple relay selection in large multi-hop decode-and-forward relay networks
2016
In this paper, we propose and investigate two novel techniques to perform multiple relay selection in large multi-hop decode-and-forward relay networks. The two proposed techniques exploit sparse signal recovery theory to select multiple relays using the orthogonal matching pursuit algorithm and outperform state-of-the-art techniques in terms of outage probability and computation complexity. To reduce the amount of collected channel state information (CSI), we propose a limited-feedback scheme where only a limited number of relays feedback their CSI. Furthermore, a detailed performance-complexity tradeoff investigation is conducted for the different studied techniques and verified by Monte …