Effect of beraprost sodium on HPH rats and expression of oxygen-sensitive Kv channels in pulmonary artery smooth muscle / 西安交通大学学报(医学版)

Objective To explore the effect of beraprost sodium (BPS) on hypoxia-induced pulmonary artery hypertension (HPH) in rats and the expression of oxygen-sensitive Kv channels in pulmonary artery smooth muscle (PASM).Methods The HPH model of rats was established by exposing rats to low-pressure and low-oxygen cabin which was auto-modulated for 8h every day.Rats in the BPS group were given an intragastric administration of BPS [300 μg/(kg · d)],while those in the control group and HPH group were given an intragastric administration of 3 ml/kg of 0.9％ saline.After 4 weeks,the mean pulmonary artery pressure (mPAP) was measured and right heart ventricle hypertrophy index (RVHI) was calculated;pulmonary artery remodeling was evaluated by HE staining;the expressions of Kv 1.2,Kv 1.5 and Kv2.1 in the pulmonary artery were detected by Real-time PCR and Western blot.Results The HPH model was successfully established in rats exposed to chronic hypoxia for 4 weeks.Compared with those in HPH group,mPAP,RVHI and pulmonary artery remodeling were decreased in BPS group [mPAP:(13.48±2.18)mmHg vs.(23.87±2.23)mmHg vs.(17.09±1.20)mmHg;RVHI:0.28±0.02 vs.0.46±0.03 vs.0.36±0.04;％ area of medial smooth muscle:35.72±6.58 vs.68.52±5.64 vs.46.58±8.43;P＜0.05],and the mRNA and protein expressions of Kv 1.2,Kv 1.5 and Kv 2.1 were increased (relative protein expression level:Kv1.2,0.78±0.10 vs.0.15±0.03 vs.0.57±0.13;Kv1.5,0.61±0.10 vs.0.31±0.05 vs.0.59±0.13;Kv2.1,0.29±0.05 vs.0.10±0.02 vs.0.28±0.07;P＜0.05).Conclusion BPS can improve pulmonary arterial hypertension induced by hypoxia,and upregulate the decreased mRNA and protein expressions of Kv 1.2,Kv 1.5 and Kv 2.1 in pulmonary artery.

Change of Kv Channel Interacting Protein 1 and Gamma-Aminobutyric Acid-ergic Neurons in Hippocampus of Pentylenetetrazole Induced Epilepsy Rats / 中国康复理论与实践

@#Objective To explore the role of Kv channel interacting protein 1(KChIP1)in the process of epileptic seizure and the relationship between KChIP1 and gamma-aminobutyric acid-(GABA)ergic neurons.Methods Normal female Sprague-Dawley rats were treated with pentylenetetrazole to make acute pentylenetetrazole models of epilepsy.Laser Scanning Confocal Microscope(LSCM)combined with double-labeled immunohistochemical technique was applied to observe the expression of the KChIP1 and the GABAergic neurons in the hippocampus of rats.Results The number of KChIP1-postive neurons in the hippocampus was significantly increased in the acute pentylenetetrazole model rats(P<0.05).There was no significant difference in the number of double-labled neurons(P>0.05),nor of the GABA-postive neurons between the model rats and the controls.The ratio of double-labeled neurons/total positive neurons was 63.9% in the hippocampus.Conclusion The KChIP1 might be involved in epileptogenesis of pentylenetetrazole induced seizure.The KChIP1 was associated with GABAergic neurons,whereas it may be functionally different from GABA.

Immunohistochemical Study on the Distribution of the Voltage-gated Ion Channels in Gerbil Cerebellum / 체질인류학회지

There is growing evidence that alterations in Ca2+ homeostasis may play a role in processes of brain aging and neurodegeneration. However, few have focused on voltage-gated Ca2+ channel (VGCC) subunits, much less on expression of other voltage-gated ion channels, i.e. voltage-gated K+ (Kv) and Na+ (Nav) channels. In the present study, we have investigated the spatial patterning of VGCCs, Kv1 and Nav channels by immunohistochemistry. This study have shown clearly that the VGCCs, Kv1 and Nav channels have differential distribution in the cerebellum of gerbil, which is used as an ischemia and epilepsy animal model. Immunoreactivities for Cav2.1, Cav1.2 and Cav1.3 were observed in the cell bodies and dendritic branches of Purkinje cells. In particular, Cav1.3 immunoreactivity was most prominent in the cell bodies and dendritic arborizations. A distinct band of punctate immunoreactivity for the Cav2.1, Cav2.2, Cav1.2 and Cav1.3 were observed in cerebellar nuclei. Strong immunoreactivities for Kv1.3, Kv1.4, Kv1.5 and Kv1.6 were observed in the Purkinje cell bodies, whereas Kv1.2 immunoreactivity was found in the basket cell axon plexus and terminal regions around the Purkinje cells. In the cerebellar nuclei, Kv1.2, Kv1.4 and Kv1.6 proteins were clearly detected in the soma of cerebellar output neurons. The most intense staining for Nav1.1 was observed in the granular layer, whereas strong immunoreactivity for Nav1.2 were seen in the Purkinje cell bodies, and extended into their dendrites. The overall results have demonstrated the expression patterns of VGCCs, Kv1 and Nav channels in gerbil cerebellum. Further studies are needed to define changes in other Ca2+ channel types to determine whether any channel changes represent selective loss of specific receptors or of cell loss, and to determine whether changes in Kv and Nav channels are linked to Ca2+ channel changes.

Role of K+ channels to resting membrane potential of rabbit middle cerebral arterial smooth muscle cells

The aim of the present study is to investigate the contribution of Ca2+-activated K+ (KCa) channels and delayed rectifier K+ (KV) channels to the resting membrane potential (RMP) in rabbit middle cerebral arterial smooth muscle cells. The RMP and membrane currents were recorded using the whole-cell patch configuration and single KCa channel was recorded using the outside-out patch configuration. Using the pipette solution containing 0.05 mM EGTA, the RMP was -25.76+/-5.08 mV (n=12) and showed spontaneous transient hyperpolarizations (STHPs). The membrane currents showed time- and voltage-dependent outward currents with spontaneous transient outward currents (STOCs). When we recorded the membrane potential using the pipette solution containing 10 mM EGTA, the RMP was depolarized and did not show STHPs. The membrane currents showed no STOCs but only showed slowly inactivating outward currents. External TEA (1 mM) reversibly inhibited the STHPs, depolarized the RMP, reduced the membrane currents, abolished STOCs, and decreased the open probability of single KCa channel. When KV currents were isolated, the application of 4-AP (5 mM) depolarized the RMP. The important aspect of our results is that KCa channel is responsible for the generation of the STHPs in the membrane potential and plays an important role in the regulation of the RMP and KV channel is also responsible for the regulation of the RMP in rabbit middle cerebral arterial smooth muscle cells.