Objective To investigate the feasibility of recombinant lentivirus (LVs) mediated hyperpolarization- activated cyclic nucleotide-gated cation channel 4 (HCN4) gene transfecting rat bone mesenchymal stem cells (BMSCs) so as to construct the biological pacemaker cells. Methods Sprague Dawley rats at the age of 3-5 weeks were selected to isolate and culture BMSCs using modified whole bone marrow adherent culture method. LVs was used as carrier, and enhanced green fluorescent protein (EGFP) as marker to build LVs-HCN4-EGFP virus liquid. The BMSCs at passage 3 were transfected with LVs-HCN4-EGFP virus liquid (experimental group) and LVs-EGFP null virus liquid (control group). Fluorescence microscope was used to observe the green fluorescent protein expression after 24, 48, and 72 hours of transfection; Western blot method was used to detect the HCN4 protein expression. The electrophysiology was used to detect the pacemaker current in the experimental group. Results After transfection, BMSCs in the experimental group showed normal morphology and good growth; scattered green fluorescence could be seen at 48 hours under fluorescence microscope, with a transfection efficiency of about 10%; the fluorescence expression increased slightly, with the transfection efficiency of 20% to 25% at 72 hours. While no expression of green fluorescence was seen in the control group. Western blot results showed that the same band expression as a relative molecular mass of HCN4 protein were found at 72 hours after transfection in the experimental group, only weak expression of protein band was seen in the control group; the gray value of the experimental group (33.75 ± 0.41) was significantly higher than that of the control group (23.39 ± 0.33) (t=17.524, P=0.013). In the experimental group, the pacemaker current was recorded, and it could be blocked by CsCl, in accordance with the characteristics of pacemaker current. Conclusion The recombinant LVs mediated HCN4 gene is successfully transfected into rat BMSCs, and the expression of HCN4 protein and the pacemaker current can be detected.
【Abstract】 Objective To investigate the expression of connexin 40 (Cx40) and hyperpolarization-activated cycl icnucleotide-gated cation channel 4 (HCN4) in rat bone marrow mesenchymal stem cells (BMSCs) cocultured with the sinoatrialnode (SAN) tissues in vitro, so as to evaluate the possibil ity of BMSCs differentiation into SAN cells. Methods BMSCs wereisolated from Sprague Dawley rats (aged 4-6 weeks, male or female) by the adhesive method and cultured; BMSCs at the 3rdpassage were marked with carboxyfluorescein succinimidyl ester, and then were incubated on 6-well culture plate; cell climingsl ices were prepared at the same time. SAN tissue was taken and cut into 0.3 cm × 0.3 cm mass, and then placed into 4℃ PBSsolution. The SAN tissue mass was cocultured with marked BMSCs at the 3rd passage for 3 weeks as the experimental group, andBMSCs at 3rd passage were cultured alone for 1 week as the control group. At 1, 2, and 3 weeks after coculture, the mean integratedabsorbance (MIA) values of Cx40 and HCN4 were measured by Image pro plus 5.0 through the method of immunohistochemistry,and the mRNA expressions of Cx40 and HCN4 were identified by real-time fluorescent quantitative PCR. Results TheMIA values of Cx40 and HCN4 in the experimental group were higher than that in the control group, showing significantdifferences (P lt; 0.01). In the experimental group, the expressions of Cx40 and HCN4 increased gradually with time. The longerthe culture time was, the higher the expressions of Cx40 and HCN4 were, showing significant differences (P lt; 0.05). The mRNAexpressions of Cx40 and HCN4 in the experimental group were significantly higher than those in the control group (P lt; 0.01); inthe experimental group, the mRNA expressions of Cx40 and HCN4 increased gradually with time, showing significant differencesbetween different time points (P lt; 0.05). Conclusion The expressions of Cx40 and HCN4 increase obviously after coculturingBMSCs with SAN tissue, indicating that BMSCs could differentiate into SAN cells by coculturing with SAN tissue in vitro.
Objective To explore the effect of hydrostatic pressure on intracellular free calcium concentration ([Ca2+]i) and the gene expression of transient receptor potential vanilloid (TRPV) in cultured human bladder smooth muscle cells (hb-SMCs), and to prel iminarily probe into the possible molecular mechanism of hb-SMCs prol iferation stimulated by hydrostatic pressure. Methods The passage 6-7 hb-SMCs were loaded with Ca2+ indicator Fluo-3/AM. When the hb-SMCs were under 0 cm H2O (1 cm H2O=0.098 kPa) (group A) or 200 cm H2O hydrostatic pressure for 30 minutes (group B) and then removing the 200 cm H2O hydrostatic pressure (group C), the [Ca2+]i was measured respectively by inverted laser anningconfocal microscope. When the hb-SMCs were given the 200 cm H2O hydrostatic pressure for 0 hour, 2 hours, 6 hours, 2 hours, and 24 hours, the mRNA expressions of TRPV1, TRPV2, and TRPV4 were detected by RT-PCR technique. Results The [Ca2+]i of group A, group B, and group C were (100.808 ± 1.724), (122.008 ± 1.575), and (99.918 ± 0.887) U, respectively; group B was significantly higher than groups A and C (P lt; 0.001). The [Ca2+]i of group C decreased to the base l ine level of group A after removing the pressure (t=0.919, P=0.394). The TRPV1, TRPV2, and TRPV4 genes expressed in hb-SMCs under 200 cm H2O hydrostatic pressure at 0 hour, 2 hours, 6 hours, 12 hours, and 24 hours, but the expressions had no obvious changes with time. There was no significant difference in the expressions of TRPV1, TRPV2, and TRPV4 among 3 groups (P gt; 0.05). Conclusion The [Ca2+]i of hb-SMCs increases significantly under high hydrostatic pressure. As possible genes in stretch-activated cation channel, the TRPV1, TRPV2, and TRPV4 express in hb-SMCs under 200 cm H2O hydrostatic pressure. It is possible that the mechanical pressure regulates the [Ca2+]i of hb-SMCs by opening the stretch-activated cation channel rather than up-regulating its expression.
Objective To study the influence of ischemia-reperfusion on the expression of the hyperpolarization activated cycl icnucleotide gated cation channel 4 (HCN4) and to discuss the mechanism of functional disturbance of sinoatrial node tissue (SANT) after ischemia reperfusion injury (IRI). Methods Eighty five healthy adult rabbits, weighing 2-3 kg, were randomly divided into 3 groups: control group [a suture passed under the root section of right coronary artery (RCA) without l igation, n=5], experimental group A (occluding the root section of RCA for 30 minutes, then loosening the root 2,4, 8 and 16 hours, n=10), experimental group B (occluding the root section of RCA for 1 hour, then loosening the root 2, 4,8 and 16 hours, n=10). At the end of the reperfusion, the SANT was cut off to do histopathological, transmission electronmicroscopical and immunohistochemical examinations and semi-quantitative analysis. Results The result of HE stainingshowed that patho-injure of sinoatrial node cell (SANC) happened in experimental groups A and B after 2 hours of reperfusion, the longer the reperfusion time was, the more serious patho-injure of SANC was after 4 and 8 hours of reperfusion, SANC reached peak of damage after 8 to 16 hours of reperfusion; patho-injure of SANC was more serious in experimental group B than in experimental group A at the same reperfusion time. Immunohistochemical staining showed that the expression of HCN4 located in cellular membrane and cytoplasm in the central area of SANC and gradually decreased from the center to borderl ine. The integral absorbance values of HCN4 expression in the control group (397.40 ± 34.11) was significantly higher than those in the experimental group A (306.20 ± 35.77, 216.60 ± 18.59, 155.40 ± 19.11 and 135.00 ± 12.30) and in the experimental group B (253.70 ± 35.66, 138.70 ± 13.28, 79.10 ± 9.60 and 69.20 ± 8.42) after 2, 4, 8 and 16 hours of reperfusion (P lt; 0.05). With reperfusion time, the expression of HCN4 of SANC decreased, which was lowest after 8 hours of reperfusion; showing significant difference among 2, 4 and 8 hours after reperfusion (P lt; 0.05) and no significant difference between 8 and 16 hours after reperfusion (P gt; 0.05). At the same reperfusion time, the expression of HCN4 was higher in the experimental group A than in the experimental group B. The result of transmission electron microscope showed that ultramicrostructure of SANC was damaged after reperfusion in experimental groups A and B. The longer the reperfusion time was, the more serious ultramicrostructure damage of SANC was, and reached the peak of damage after 8 hours of reperfusion. Ultramicrostructure of SANC was not different between 8 and 16 hours of reperfusion. At the same reperfusion time, the ultramicrostructure damage of SANC was moreserious in experimental group B than in experimental group A. Conclusion IRI is harmful to the morphous and structure ofSANC, and effects the expression of HCN4 of SANC, which is concerned with functional disturbance and arrhythmia.
ObjectiveTo investigate the community residents' awareness of knowledge on cardiovascular disease prevention and control and their access methods to relevant information. MethodsBetween June and August, 2013, the residents aged above 45 who came to community health center for diagnosis or treatment were investigated by questionnaires including the acknowledge of prevention for cardiovascular diseases and the access methods to relevant information. ResultsA total of 1 000 residents were involved in this study, including 394 (39.40%) males and 606 (60.60%) females aged from 45 to 98 with an average of 68.3±10.4. The highest rate of awareness of cardiovascular prevention knowledge was regular physical exercise (89.20%), followed by low salt diet (67.20%) and fried food (6.30%). The highest rate of access to the information was information provided verbally by doctors or nurses (77.50%), followed by television and radio (56.00%). ConclusionCommunity center should strengthen the health education of cardiovascular disease prevention and control. Health education should be practiced in an easy way for the residents.
Ion channels are involved in the mechanism of anesthetic action and side effect. The transcription and expression of ion channel genes can be modulated by general anesthetics. The adverse effect of continuous infusion of etomidate has been concerned. However, the effects of etomidate on mRNA expressions of ion channel genes remain unclear. In this study, we exposed Daphnia pulex in 250 μmol/L of etomidate for 240 min and observed the change of heart rate, phototactic behavior and blood glucose during the period of exposure, as well as the mRNA expressions of 120 ion channel genes at the end of the experiment. Compared to the controls, heart rate, phototactic behavior and blood glucose were not influenced by 250 μmol/L of etomidate. According to the quantitative PCR results, 18 of 120 Daphnia pulex ion channel genes transcripts were affected by persistent 240 min exposure to 250 μmol/L of etomidate: 2 genes were upregulated and 16 genes were down-regulated, suggesting that etomidate showed effects on many different ion channels in transcription level. Systematical exploration of transcriptional changes of ion channels could contribute to understanding of the pharmacological mechanism of etomidate.
Mechanical stress modulates almost all functions of cells. The key to exploring its biological effects lies in studying the perception of mechanical stress and its mechanism of mechanotransduction. This article details the perception and mechanotransduction mechanism of mechanical stress by extracellular matrix, cell membrane, cytoskeleton and nucleus. There are two main pathways for the perception and mechanotransduction of mechanical stress by cells, one is the direct transmission of force, and the other is the conversion of mechanical signal into chemical signal. The purpose of this study is to provide some reference for the exploration of precise treatment of mechanical stress-related diseases and the optimization of construction of tissue engineered organs by mechanical stress.
Objective To summarize the role of Piezo mechanosensitive ion channels in the osteoarticular system, in order to provide reference for subsequent research. Methods Extensive literature review was conducted to summarize the structural characteristics, gating mechanisms, activators and blockers of Piezo ion channels, as well as their roles in the osteoarticular systems. Results The osteoarticular system is the main load-bearing and motor tissue of the body, and its ability to perceive and respond to mechanical stimuli is one of the guarantees for maintaining normal physiological functions of bones and joints. The occurrence and development of many osteoarticular diseases are closely related to abnormal mechanical loads. At present, research shows that Piezo mechanosensitive ion channels differentiate towards osteogenesis by responding to stretching stimuli and regulating cellular Ca2+ influx signals; and it affects the proliferation and migration of osteoblasts, maintaining bone homeostasis through cellular communication between osteoblasts-osteoclasts. Meanwhile, Piezo1 protein can indirectly participate in regulating the formation and activity of osteoclasts through its host cells, thereby regulating the process of bone remodeling. During mechanical stimulation, the Piezo1 ion channel maintains bone homeostasis by regulating the expressions of Akt and Wnt1 signaling pathways. The sensitivity of Piezo1/2 ion channels to high strain mechanical signals, as well as the increased sensitivity of Piezo1 ion channels to mechanical transduction mediated by Ca2+ influx and inflammatory signals in chondrocytes, is expected to become a new entry point for targeted prevention and treatment of osteoarthritis. But the specific way mechanical stimuli regulate the physiological/pathological processes of bones and joints still needs to be clarified. Conclusion Piezo mechanosensitive ion channels give the osteoarticular system with important abilities to perceive and respond to mechanical stress, playing a crucial mechanical sensing role in its cellular fate, bone development, and maintenance of bone and cartilage homeostasis.