Search results for "ion channels"
showing 10 items of 137 documents
TRESK channel contributes to depolarization-induced shunting inhibition and modulates epileptic seizures.
2020
Glutamatergic and GABAergic synaptic transmission controls excitation and inhibition of postsynaptic neurons, whereas activity of ion channels modulates neuronal intrinsic excitability. However, it is unclear how excessive neuronal excitation affects intrinsic inhibition to regain homeostatic stability under physiological or pathophysiological conditions. Here, we report that a seizure-like sustained depolarization can induce short-term inhibition of hippocampal CA3 neurons via a mechanism of membrane shunting. This depolarization-induced shunting inhibition (DShI) mediates a non-synaptic, but neuronal intrinsic, short-term plasticity that is able to suppress action potential generation and…
Understanding 802.11e contention-based prioritization mechanisms and their coexistence with legacy 802.11 stations
2005
The IEEE 802.11e task group has reached a stable consensus on two basic contention-based priority mechanisms to promote for standardization: usage of different arbitration interframe spaces and usage of different minimum/maximum contention windows. The goal of this article is to provide a thorough understanding of the principles behind their operation. To this purpose, rather than limit our investigation to high-level (e.g. throughput and delay) performance figures, we take a closer look at their detailed operation, also in terms of low-level performance metrics (e.g., the probability of accessing specific channel slots). Our investigation on one hand confirms that AIFS differentiation prov…
Zinc accelerates respiratory burst termination in human PMN
2021
The respiratory burst of phagocytes is essential for human survival. Innate immune defence against pathogens relies strongly on reactive oxygen species (ROS) production by the NADPH oxidase (NOX2). ROS kill pathogens while the translocation of electrons across the plasma membrane via NOX2 depolarizes the cell. Simultaneously, protons are released into the cytosol. Here, we compare freshly isolated human polymorphonuclear leukocytes (PMN) to the granulocytes-like cell line PLB 985. We are recording ROS production while inhibiting the charge compensating and pH regulating voltage-gated proton channel (HV1). The data suggests that human PMN and the PLB 985 generate ROS via a general mechanism,…
HPLC demonstration that an all Trp--Phe replacement in gramicidin A results in a conformational rearrangement from beta-helical monomer to double-str…
1995
We have taken advantage of our previously reported high performance liquid chromatographic (HPLC) strategy to investigate the conformational behavior of the optically reversed gramicidin M (gM-), an analog of gramicidin A with all tryptophans replaced by phenylalanines, in different model membranes. It is quantitatively demonstrated for the first time that once inserted in the lipid environment, gM- (unlike the native peptide) undergoes a conformational transition from beta-helical monomers to thermodynamically stable double-stranded dimers. This transition is faster the higher the incubation temperature and can be neatly observed in both small unilamellar phospholipid vesicles and lysophos…
TRPV1 channels in nitric oxide-mediated signalling: insight on excitatory transmission in rat CA1 pyramidal neurons
2022
Nitric oxide (NO) is a fascinating signalling molecule implicated in a plethora of biological functions, especially at the synaptic level. Exploring neurotransmission in the hippocampus could be instrumental in the individuation of putative targets for nitric-oxide mediated neuromodulation, especially in terms of the potential repercussions on fundamental processes i.e. synaptic plasticity and excitability-related phenomena. Among these targets, endovanilloid signalling constitutes an object of study since Transient Receptors Vanilloid type 1 (TRPV1) channels possess a NO-sensitive gate modulating its activation. Also, NO has been referred to as a mediator for numerous endocannabinoid effec…
The Concise Guide To Pharmacology 2021/22: G Protein-Coupled Receptors
2021
The Concise Guide to PHARMACOLOGY 2021/22 is the fifth in this series of biennial publications. The Concise Guide provides concise overviews, mostly in tabular format, of the key properties of nearly 1900 human drug targets with an emphasis on selective pharmacology (where available), plus links to the open access knowledgebase source of drug targets and their ligands (www.guidetopharmacology.org), which provides more detailed views of target and ligand properties. Although the Concise Guide constitutes over 500 pages, the material presented is substantially reduced compared to information and links presented on the website. It provides a permanent, citable, point-in-time record that will s…
Blocking of an ion channel by a highly charged drug: Modeling the effects of applied voltage, electrolyte concentration, and drug concentration
2005
We present a simple physical model to estimate the blocked pore probability of an ion channel that can be blocked by a highly charged drug in solution. The model is inspired by recent experimental work on the blocking of the ${\mathrm{PA}}_{63}$ channel, involved in the anthrax toxin infection, by a highly charged drug [Karginov et al. PNAS 102, 15075 (2005)]. The drug binding to the pore is highly specific but the strong dependence of blocking on the applied voltage and electrolyte concentration suggests that long range electrostatic interactions are important. Since basic electrostatic concepts rather than detailed molecular models are considered, the microscopic details of the channel bl…
A key role for cyclic nucleotide gated (CNG) channels in cGMP-related retinitis pigmentosa.
2011
The rd1 natural mutant is one of the first and probably the most commonly studied mouse model for retinitis pigmentosa (RP), a severe and frequently blinding human retinal degeneration. In several decades of research, the link between the increase in photoreceptor cGMP levels and the extremely rapid cell death gave rise to a number of hypotheses. Here, we provide clear evidence that the presence of cyclic nucleotide gated (CNG) channels in the outer segment membrane is the key to rod photoreceptor loss. In Cngb1(-/-) x rd1 double mutants devoid of regular CNG channels, cGMP levels are still pathologically high, but rod photoreceptor viability and outer segment morphology are greatly improve…
Peripherin-2 couples rhodopsin to the CNG channel in outer segments of rod photoreceptors.
2014
Outer segments (OS) of rod photoreceptors are cellular compartments specialized in the conversion of light into electrical signals. This process relies on the light-triggered change in the intracellular levels of cyclic guanosine monophosphate (cGMP), which in turn controls the activity of cyclic nucleotide-gated (CNG) channels in the rod OS plasma membrane. The rod CNG channel is a macromolecular complex that in its core harbors the ion-conducting CNGA1 and CNGB1a subunits. To identify additional proteins of the complex that interact with the CNGB1a core subunit we applied affinity purification of mouse retinal proteins followed by mass spectrometry. In combination with in vitro and in viv…
Carbohydrate-Mediated Biomolecular Recognition and Gating of Synthetic Ion Channels
2013
Nanochannel-based biosensing devices have been proposed for selective detection of protein analyte molecules. However, the design and miniaturization of reusable channel-based biosensors is still a challenge in nanoscience and biotechnology. We present here a reusable nanofluidic biosensor based on reversible lectin-carbohydrate interactions. The nanochannels are fabricated in heavy ion tracked polymer membranes. The channel walls are functionalized with p-aminophenyl alpha-D-mannopyranoside (APMP) monolayers through carbodiimide coupling chemistry. The chemical (mannopyranoside) groups on the inner channel walls serve as binding sites and interact with specific protein molecules. The bindi…