ABSTRACT
Weightlessness in the space environment affects astronauts' learning memory and cognitive function. Repetitive transcranial magnetic stimulation has been shown to be effective in improving cognitive dysfunction. In this study, we investigated the effects of repetitive transcranial magnetic stimulation on neural excitability and ion channels in simulated weightlessness mice from a neurophysiological perspective. Young C57 mice were divided into control, hindlimb unloading and magnetic stimulation groups. The mice in the hindlimb unloading and magnetic stimulation groups were treated with hindlimb unloading for 14 days to establish a simulated weightlessness model, while the mice in the magnetic stimulation group were subjected to 14 days of repetitive transcranial magnetic stimulation. Using isolated brain slice patch clamp experiments, the relevant indexes of action potential and the kinetic property changes of voltage-gated sodium and potassium channels were detected to analyze the excitability of neurons and their ion channel mechanisms. The results showed that the behavioral cognitive ability and neuronal excitability of the mice decreased significantly with hindlimb unloading. Repetitive transcranial magnetic stimulation could significantly improve the cognitive impairment and neuroelectrophysiological indexes of the hindlimb unloading mice. Repetitive transcranial magnetic stimulation may change the activation, inactivation and reactivation process of sodium and potassium ion channels by promoting sodium ion outflow and inhibiting potassium ion, and affect the dynamic characteristics of ion channels, so as to enhance the excitability of single neurons and improve the cognitive damage and spatial memory ability of hindlimb unloading mice.
Subject(s)
Animals , Mice , Transcranial Magnetic Stimulation , Hindlimb Suspension , Neurons , Cognitive Dysfunction , BrainABSTRACT
Scorpion venoms are natural sources of molecules that have, in addition to their toxic function, potential therapeutic applications. In this source the neurotoxins can be found especially those that act on potassium channels. Potassium channels are responsible for maintaining the membrane potential in the excitable cells, especially the voltage-dependent potassium channels (Kv), including Kv1.3 channels. These channels (Kv1.3) are expressed by various types of tissues and cells, being part of several physiological processes. However, the major studies of Kv1.3 are performed on T cells due its importance on autoimmune diseases. Scorpion toxins capable of acting on potassium channels (KTx), mainly on Kv1.3 channels, have gained a prominent role for their possible ability to control inflammatory autoimmune diseases. Some of these toxins have already left bench trials and are being evaluated in clinical trials, presenting great therapeutic potential. Thus, scorpion toxins are important natural molecules that should not be overlooked in the treatment of autoimmune and other diseases.(AU)
Subject(s)
Animals , Scorpion Venoms/toxicity , Potassium Channels , Immunosuppression Therapy/methodsABSTRACT
Objective To evaluate the effects of remifentanil (RMF)on large conductance cal-cium-activated potassium channel (BKCa)and voltage-gated potassium channel (KV)activition currents in basilar arterial smooth muscle cells (BASMCs)of normotensive and hypertensive rats. Methods Spontaneously hypertensive rats (SHR)and homologous normotensive wistar-kyoto (WKY)rats,were used in this study.BASMCs were obtained freshly by the method of enzymolysis. Six basilar artery smooth muscle cells of each rat were chosen and analyzed.Outward current ampli-tude was recorded by the whole-cell patch clamp technique.The outward current amplitude under all stimulation voltage in set of step stimulation protocol before (basal level)and after administration of RMF (3×10-7mol/L)were recorded respectively and net current was calculated (net current=cur-rent amplitude after administration-basic value).With administration by concentrations cumulative method,the current amplitude under +60 mV stimulation voltage was separately recorded before (basic value)and after application of different concentrations of RMF (10-10,10-9,10-8,10-7, 10-6,10-5mol/L),then calculated current increasing rate and the half effective concentration (EC50)of RMF increasing current amplitude in BASMCs.Another six basilar artery smooth muscle cells of each rat were chosen and given RMF (3×10-7mol/L),and separately treated with BKCa channel blocker (tetraethylammonium,TEA)and Kv channel blocker (4-aminopyridine,4-AP),and then administrated the corresponding RMF mixture.The current amplitude was recorded after each dose.Results At 0,+20,+40 and +60 mV,the net current generated by RMF on both BASMCs of rats was successively and significantly increased (P <0.05).The increment rate of outward currents in BASMCs generated by 10-10,10-9,10-8,10-7RMF successively and significantly went upward (P<0.05).Compared to WKY rats,the half-effective concentration(EC50)of RMF increas-ing the current amplitude in BASMCs of SHR significantly rose(P<0.05).Compared with the base-line,the current amplitude in BASMCs of the two kind rats was significantly increased after adminis-tration of RMF,and decreased after administration of TEA or 4-AP (P<0.05);Compared to ad-ministration of TEA or 4-AP,the current amplitude in BASMCs of the two kind rats was significantly in-creased after administration of TEA+RMF or 4-AP+RMF (P<0.05).Conclusion Bkcaand Kv currents in both BASMCs of SHR and WKY rats were activated by RMF in a voltage-dependent and dose-dependent manner,and the effect of RMF on BKCaand Kvactivition currents in BASMCs of SHR was weaker than WKY rats.
ABSTRACT
No abstract available.
Subject(s)
Glioma , Limbic Encephalitis , Potassium Channels, Voltage-Gated , SeizuresABSTRACT
Voltage-gated potassium channels regulate cell membrane potential and excitability in neurons. Trigeminal ganglion as a primary sensory neuron plays an important role in the pain transduction and transmission of trigeminal neuralgia. Trigeminal ganglion neurons express many subtypes of voltage-gated potassium channels and they can evoke different type of K+ current when activated. The alteration of voltage-gated potassium channels and their interaction with neurotransmitters, inflammatory cytokines and receptors play important roles in the development of trigeminal neuralgia.
ABSTRACT
Objective To determine the effect of cardiomyopeptidin on transient outward potassium current(I_(to) of rat ventricular myocytes and its action mechanism on the ion channels of myocardium.Methods Single ventricular myocytes of rats were obtained by enzymatic dissociation.The whole-cell patch-clamp recording technique was used to record the change of transient outward potassium current(I_(to) by different dosages of cardiomyopeptidin.Results Cardiomyopeptidin decreased I_(to) in a dose-dependent manner.Cardiomyopeptidin in dose of 10,50,100,250 and(500 mg/L) decreased I_(to %) by 4,13,22,32 and 38 respectively.Cardiomyopeptidin 50 mg/L moved the current density-voltage curve of I_(to) down,but the shape of the curve had no changes.Cardiomyopeptidin 50 mg/L did not change the steady state activation curve of I_(to).Conclusions Cardiomyopeptidin decreases the I_(to) of rat ventricular myocytes,which might be one of the mechanisms of its antiarrhythmic effect.
ABSTRACT
@#ObjectiveTo analyze the clinical features and pathogenesis mechanism of Isaacs syndrome.MethodsA case with Isaacs syndrome was reporttedResults and ConclusionIsaacs syndrome is characterized by the occurrence of spontaneous and continuous muscle fiber activity, associated with muscle cramps, pseudomyotonia and myokymia, stiffness and delayed relaxation of the muscle. The stiffness and myokymia are present at rest and during sleep. Isaacs syndrome has been recently suggested to be produced through an immune-mediated mechanism in which voltage-gated potassium channels may be targeted by auto-antibodies.