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BACKGROUND:Muscle weakness is a common symptom after coronavirus disease 2019(COVID-19)infection and affects the ability to perform daily activities in humans during recovery.Low-frequency pulsed magnetic field stimulation at a strength of 1.5 mT and a frequency of 3 300 Hz can enhance the maximal voluntary contraction and strength endurance of human skeletal muscle by inducing and activating classical transient receptor potential channel 1(TRPC1),which produces a series of pathological support effects on muscle tissue.It has not been studied whether this means will improve muscle weakness in patients recovering from COVID-19. OBJECTIVE:To select the low-frequency pulsed magnetic field for magnetic stimulation of lower limb muscle groups in patients with COVID-19,in order to observe the effect of this stimulation on the improvement of muscle weakness of lower limb muscle groups in patients with COVID-19 during the recovery period. METHODS:Fourteen patients infected with COVID-19(Omicron strain)positive for Innovita COVID-19 Ab Test(Colloidal Gold)and accompanied by muscle weakness were recruited and randomly divided into two groups:a test group receiving magnetic field stimulation and a control group receiving sham treatment,respectively.The total duration of the trial was 3 weeks.The test group was given low-frequency pulsed magnetic stimulation of the lower limbs every 48 hours and the control group was given the same intervention procedure as the test group but with sham stimulation.Patients in both groups were not informed whether the magnetic stimulation apparatus was running or not.Nine sessions were performed in both groups and the changes in the maximum voluntary contraction,explosive leg force and strength endurance of the local muscle groups of the lower limbs were subsequently observed in both groups. RESULTS AND CONCLUSION:Among the eight local muscle groups collected,seven local muscle groups in the test group showed an increase in the maximum voluntary contraction value after 3 weeks of low-frequency pulsed magnetic field stimulation.In the control group,there were only three muscle groups with improvement in the maximum voluntary contraction.The rate of improvement in the anterior and posterior muscle groups of the left leg in the test group was significantly higher than that in the control group.The longitudinal jump height and peak angular velocity of the knee joint in both groups were improved compared with the pre-test measurement,and the elevation rate of jumping height in the test group was higher than that in the control group.Under the fatigue condition,the decline rates of peak angular velocity of the knee joint and jumping height in the test group decreased significantly,while those in the control group did not change significantly.The above data confirmed that the low-frequency pulsed magnetic field stimulation with the intensity of 1.5 mT and frequency of 3 300 Hz could improve the muscle strength of more local muscle groups in the lower limbs of patients with COVID-19 during the recovery period compared with the human self-healing process,and the whole-body coordination ability and functional status based on explosive leg force of the legs could be significantly improved.Therefore,low-frequency pulsed magnetic field stimulation can be used as an effective,non-exercise rehabilitation tool to improve muscle weakness in the lower limbs of patients with COVID-19.
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The canonical transient receptor potential channel(TRPC)proteins form Ca2+-permeable cation channels that are involved in various heart diseases.However,the roles of specific TRPC proteins in myocardial ischemia/reperfusion(I/R)injury remain poorly understood.We observed that TRPC1 and TRPC6 were highly expressed in the area at risk(AAR)in a coronary artery ligation induced I/R model.Trpc1-/-mice exhibited improved cardiac function,lower serum Troponin T and serum creatine kinase level,smaller infarct volume,less fibrotic scars,and fewer apoptotic cells after myocardial-I/R than wild-type or Trpc6-/-mice.Cardiomyocyte-specific knockdown of Trpc1 using adeno-associated virus 9 mitigated myocardial I/R injury.Furthermore,Trpc1 deficiency protected adult mouse ventricular myocytes(AMVMs)and HL-1 cells from death during hypoxia/reoxygenation(H/R)injury.RNA-sequencing-based transcriptome analysis revealed differential expression of genes related to reactive oxygen species(ROS)generation in Trpc1-/-cardiomyocytes.Among these genes,oxoglutarate dehydrogenase-like(Ogdhl)was markedly downregulated.Moreover,Trpc1 deficiency impaired the calcineurin(CaN)/nuclear factor-kappa B(NF-κB)signaling pathway in AMVMs.Suppression of this pathway inhibited Ogdhl upregulation and ROS generation in HL-1 cells under H/R conditions.Chromatin immunoprecipitation assays confirmed NF-κB binding to the Ogdhl promoter.The cardioprotective effect of Trpc1 deficiency was canceled out by overexpression of NF-κB and Ogdhl in cardiomyocytes.In conclusion,our findings reveal that TRPC1 is upregulated in the AAR following myocardial I/R,leading to increased Ca2+influx into associated cardiomyocytes.Subsequently,this upregulates Ogdhl expression through the CaN/NF-κB signaling pathway,ultimately exacerbating ROS production and aggravating myocardial I/R injury.
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Astrocytes are non-excitable cells in the brain and their activity largely depends on the intracellular calcium (Ca²⁺) level. Therefore, maintaining the intracellular Ca²⁺ homeostasis is critical for proper functioning of astrocytes. One of the key regulatory mechanisms of Ca²⁺ homeostasis in astrocytes is the store-operated Ca²⁺ entry (SOCE). This process is mediated by a combination of the Ca²⁺-store-depletion-sensor, Stim, and the store-operated Ca²⁺-channels, Orai and TrpC families. Despite the existence of all those families in astrocytes, previous studies have provided conflicting results on the molecular identification of astrocytic SOCE. Here, using the shRNA-based gene-silencing approach and Ca²⁺-imaging from cultured mouse astrocytes, we report that Stim1 in combination with Orai1 and Orai3 contribute to the major portion of astrocytic SOCE. Gene-silencing of Stim1 showed a 79.2% reduction of SOCE, indicating that Stim1 is the major Ca²⁺-store-depletion-sensor. Further gene-silencing showed that Orai1, Orai2, Orai3, and TrpC1 contribute to SOCE by 35.7%, 20.3%, 26.8% and 12.2%, respectively. Simultaneous gene-silencing of all three Orai subtypes exhibited a 67.6% reduction of SOCE. Based on the detailed population analysis, we predict that Orai1 and Orai3 are expressed in astrocytes with a large SOCE, whereas TrpC1 is exclusively expressed in astrocytes with a small SOCE. This analytical approach allows us to identify the store operated channel (SOC) subtype in each cell by the degree of SOCE. Our results propose that Stim1 in combination with Orai1 and Orai3 are the major molecular components of astrocytic SOCE under various physiological and pathological conditions.
Assuntos
Animais , Humanos , Camundongos , Astrócitos , Encéfalo , Cálcio , HomeostaseRESUMO
To investigate the inhibitory effect of Huangqi Danshen decoction (HDD) on isoproterenol (ISO)-induced myocardial remodeling and explore its effect on STIM1, TRPC1, CaN and NFATc3 expressions. ISO (2.5 mg•kg⁻¹•d⁻¹×14 d) was given by subcutaneous injection to establish myocardial remodeling models in rats, and then were randomly divided into control group, ISO model group, HDD5 group (HDD 5 g•kg⁻¹•d⁻¹+ISO), and HDD10 group (HDD 10 g•kg⁻¹•d⁻¹+ISO). After intervention for 4 weeks, the heart mass index (HW/BW) and the left ventricular mass index (LVW/BW) were calculated; the structure of myocardium was observed by echocardiography; the pathological changes of myocardium were observed by HE staining; levels of BNP, CaN and CaM kinases II in serum were detected by ELISA, and the protein expression levels of STIM1, TRPC1, p-CaN, p-NFATc3, and NFATc3 in left ventricular tissues were detected by Western blot. The results showed that the HW/BW and LVW/BW in ISO group were greater than those in HDD5 group and HDD10 group (P<0.05); Echocardiography showed that HDD inhibited ISO-induced increase in LVEDD and LVESD; ELISA results showed that HDD could significantly inhibit the increase of BNP, CaN and CaM kinases II levels in serum of rats with ISO-induced myocardial remodeling (P<0.01). Western blot results showed that STIM1, TRPC1, p-CaN, p-NFATc3 and NFATc3 expression levels were increased in the myocardial tissues of ISO group rats, and after HDD administration, the above expression levels were decreased in group ISO, HDD for myocardial tissue after administration of STIM1, TRPC1, p-CaN, p-NFATc3 and NFATc3 expression decreased (P<0.05). Our findings indicated that HDD can attenuate the myocardial remodeling induced by ISO, and its mechanism may be related to down-regulating the expression levels of STIM1, TRPC1, CaM kinases II, p-CaN/CaN and p-NFATc3/NFATc3.
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Conflicting evidence has been obtained regarding whether transient receptor potential cation channels (TRPC) are store-operated channels (SOCs) or receptor-operated channels (ROCs). Moreover, the Ca/Na permeability ratio differs depending on whether the current-voltage (I-V) curve has a doubly rectifying shape or inward rectifying shape. To investigate the calcium permeability of TRPC4 channels, we attached GCaMP6s to TRPC4 and simultaneously measured the current and calcium signals. A TRPC4 specific activator, (–)-englerin A, induced both current and calcium fluorescence with the similar time course. Muscarinic receptor stimulator, carbachol, also induced both current and calcium fluorescence with the similar time course. By forming heteromers with TRPC4, TRPC1 significantly reduced the inward current with outward rectifying I-V curve, which also caused the decrease of calcium fluorescence intensity. These results suggest that GCaMP6s attached to TRPC4 can detect slight calcium changes near TRPC4 channels. Consequently, TRPC4-GCaMP6s can be a useful tool for testing the calcium permeability of TRPC4 channels.