硝苯地平联合贝那普利治疗糖尿病肾病的临床观察

目的:观察硝苯地平联合贝那普利治疗糖尿病肾病的临床疗效。方法:将98例糖尿病肾病患者随机均分为2组,观察组49例采用硝苯地平联合贝那普利治疗,对照组49例仅采用硝苯地平治疗,比较2组的临床疗效和收缩压/舒张压(SBP/DBP)、空腹血糖(FBG)、24h尿α1-微球蛋白(α1-MG)和尿微量白蛋白(mAlb)水平的变化。结果:观察组的总有效率明显高于对照组(P<0.05)。与治疗前比较,2组治疗后SBP、DBP、FBG、α1-MG和mAlb水平均明显下降(P<0.05)。观察组治疗后α1-MG和mAlb水平均明显低于对照组(P<0.05),但FBG和SBP、DBP水平比较,差异均无统计学意义(P>0.05)。结论:硝苯地平联合贝那普利治疗糖尿病肾病能够明显提高临床疗效,降低血糖、血压和蛋白尿,减少对肾脏的损伤。     

Baicalein, isolated from Scutellaria baicalensis, protects against endothelin-1-induced pulmonary artery smooth muscle cell proliferation via inhibition of TRPC1 channel expression

Ethnopharmacological relevance

We investigated the antiproliferative effects of baicalein, isolated from Scutellaria baicalensis (Huang-qin), on ET-1-mediated pulmonary artery smooth muscle cells (PASMCs) proliferation and the mechanisms underlying these effects.

Materials and methods

Intrapulmonary artery smooth muscle cells were isolated and cultured from female Sprague-Dawley rats and used during passages 3-6. The proliferation of PASMCs was quantified by cell counting and XTT assay. The protein expression of TRPC1 and PKCα were determined by western blotting. The cell cycle pattern was assayed by flow cytometry. The intracellular calcium concentrations ([Ca²⁺]_i) were measured using the fluorescent indicator fura-2-AM and flow cytometry.

Results

Baicalein (0.3-3 μM) inhibited PASMCs proliferation, promoted cell cycle progression, enhanced [Ca²⁺]_i levels, increased capacitative Ca²⁺ entry (CCE), upregulated the canonical transient receptor potential 1 (TRPC1) channel and membrane protein kinase Cα (PKCα) expression induced by ET-1 (0.1 μM). The PKC activator PMA (1 μM) reversed the inhibitory effects of baicalein on ET-1-induced upregulation of TRPC1 expression and S phase accumulation, while the PKC inhibitor chelerythrine (1 μM) potentiated baicalein-mediated G₂/M phase arrest and TRPC1 channel inhibition.

Conclusion

Our findings suggest that baicalein protects against ET-1-induced PASMCs proliferation via modulation of the PKC-mediated TRPC channel.     

Possibility of application of calcium carbonate in pulpotomy of rat molars

We investigated restitution processes in mechanically exposed rat molar pulp during pulpotomy with calcium carbonate (CC). The results of the CC treatment were then compared with Calvital^®-containing calcium hydroxide (CH). Micro-computerized tomography (micro-CT), hematoxylin and eosin (H&E) staining and immunoreactivity for nestin, dentin matrix protein-1 (DMP-1) and osteopontin (OPN) were also analyzed. The increment of dentinlike calcified tissue in the pulp was observed by micro-CT. Both CC and CH groups induced pulpotomy resulted in changes associated with inflammation followed by progressive odontoblasts differentiation, dentin matrix secretion and dentin-like bridge formation. Necrotic layer formation and moderate to severe inflammation occurred during the early stages in the CH group. Necrotic layer formation was not observed in the CC group and only associated with mild to moderate inflammation. Immunoreactivity of nestin was observed earlier in the CC group than the CH group. In the CC group, immunoreactivity of DMP-1 was identified beneath the amputated site after 7 days, before increasing until 28 days, and immunoreactivity of OPN was observed in the dentin-like bridge at 28 days, which was also similar to the CH group. These findings suggested that the primary processes of reparative dentinogenesis after pulpotomy with CC may involve natural pulpal wound-healing mechanisms that are similar to the restitution processes observed during pulpotomy with CH. However, CC may prove to be less irritation and more calcified tissue formation than traditional CH-based materials when used as a pulpotomy agent.     

Subcutaneous tissue reaction to castor oil bean and calcium hydroxide in rats

Castor oil bean cement (COB) is a new material that has been used as an endodontic sealer, and is a candidate material for direct pulp capping.

Objective

The purpose of this study was to evaluate the biocompatibility of a new formulation of COB compared to calcium hydroxide cement (CH) and a control group without any material, in the subcutaneous tissue of rats.

Material and methods

The materials were prepared, packed into polyethylene tubes, and implanted in the rat dorsal subcutaneous tissue. Animals were sacrificed at the 7th and 50th days after implantation. A quantitative analysis of inflammatory cells was performed and data were subjected to ANOVA and Tukey''s tests at 5% significance level.

Results

Comparing the mean number of inflammatory cells between the two experimental groups (COB and CH) and the control group, statistically significant difference (p=0.0001) was observed at 7 and 50 days. There were no significant differences (p=0.111) between tissue reaction to CH (382 inflammatory cells) and COB (330 inflammatory cells) after 7 days. After 50 days, significantly more inflammatory cells (p=0.02) were observed in the CH group (404 inflammatory cells) than in the COB group (177 inflammatory cells).

Conclusions

These results demonstrate that the COB cement induces less inflammatory response within long periods.     

Heat stress responses modulate calcium regulations and electrophysiological characteristics in atrial myocytes

Heat stress-induced responses change the ionic currents and calcium homeostasis. However, the molecular insights into the heat stress responses on calcium homeostasis remain unclear. The purposes of this study were to examine the mechanisms of heat stress responses on calcium handling and electrophysiological characteristics in atrial myocytes. We used indo-1 fluorimetric ratio technique and whole-cell patch clamp to investigate the intracellular calcium, action potentials, and ionic currents in isolated rabbit single atrial cardiomyocytes with or without (control) exposure to heat stress (43 °C, 15 min) 5 ± 1 h before experiments. The expressions of sarcoplasmic reticulum ATPase (SERCA2a), and Na⁺-Ca²⁺ exchanger (NCX) in the control and heat stress-treated atrial myocytes were evaluated by Western blot and real-time PCR. As compared with control myocytes, the heat stress-treated myocytes had larger sarcoplasmic reticulum calcium content and larger intracellular calcium transient with a shorter decay portion. Heat stress-treated myocytes also had larger L-type calcium currents, transient outward potassium currents, but smaller NCX currents. Heat stress responses increased the protein expressions, SERCA2a, NCX, and heat shock protein. However, heat stress responses did not change the RNA expression of SERCA2a and NCX. In conclusion, heat stress responses change calcium handling through protein but not RNA regulation.     

5-HT4 and 5-HT2 receptors antagonistically influence gap junctional coupling between rat auricular myocytes

5-hydroxytryptamine-4 (5-HT₄) receptors have been proposed to contribute to the generation of atrial fibrillation in human atrial myocytes, but it is unclear if these receptors are present in the hearts of small laboratory animals (e.g. rat). In this study, we examined presence and functionality of 5-HT₄ receptors in auricular myocytes of newborn rats and their possible involvement in regulation of gap junctional intercellular communication (GJIC, responsible for the cell-to-cell propagation of the cardiac excitation). Western-blotting assays showed that 5-HT₄ receptors were present and real-time RT-PCR analysis revealed that 5-HT_4b was the predominant isoform. Serotonin (1 μM) significantly reduced cAMP concentration unless a selective 5-HT₄ inhibitor (GR113808 or ML10375, both 1 μM) was present. Serotonin also reduced the amplitude of L-type calcium currents and influenced the strength of GJIC without modifying the phosphorylation profiles of the different channel-forming proteins or connexins (Cxs), namely Cx40, Cx43 and Cx45. GJIC was markedly increased when serotonin exposure occurred in presence of a 5-HT₄ inhibitor but strongly reduced when 5-HT_2A and 5-HT_2B receptors were inhibited, showing that activation of these receptors antagonistically regulated GJIC. The serotoninergic response was completely abolished when 5-HT₄, 5-HT_2A and 5-HT_2B were simultaneously inhibited. A 24 h serotonin exposure strongly reduced Cx40 expression whereas Cx45 was less affected and Cx43 still less. In conclusion, this study revealed that 5-HT₄ (mainly 5-HT_4b), 5-HT_2A and 5-HT_2B receptors coexisted in auricular myocytes of newborn rat, that 5-HT₄ activation reduced cAMP concentration, I_CaL and intercellular coupling whereas 5-HT_2A or 5-HT_2B activation conversely enhanced GJIC.     

Specificities of atrial electrophysiology: Clues to a better understanding of cardiac function and the mechanisms of arrhythmias

The electrical properties of the atria and ventricles differ in several aspects reflecting the distinct role of the atria in cardiac physiology. The study of atrial electrophysiology had greatly contributed to the understanding of the mechanisms of atrial fibrillation (AF). Only the atrial L-type calcium current is regulated by serotonine or, under basal condition, by phosphodiesterases. These distinct regulations can contribute to I_Ca down-regulation observed during AF, which is an important determinant of action potential refractory period shortening. The voltage-gated potassium current, I_Kur, has a prominent role in the repolarization of the atrial but not ventricular AP. In many species, this current is based on the functional expression of K_V1.5 channels, which might represent a specific therapeutic target for AF. Mechanisms regulating the trafficking of K_V1.5 channels to the plasma membrane are being actively investigated. The resting potential of atrial myocytes is maintained by various inward rectifier currents which differ with ventricle currents by a reduced density of I_K1, the presence of a constitutively active I_KACh and distinct regulation of I_KATP. Stretch-sensitive or mechanosensitive ion channels are particularly active in atrial myocytes and are involved in the secretion of the natriuretic peptide. Integration of knowledge on electrical properties of atrial myocytes in comprehensive schemas is now necessary for a better understanding of the physiology of atria and the mechanisms of AF.     

Targeted GLUT-4 deficiency in the heart induces cardiomyocyte hypertrophy and impaired contractility linked with Ca and proton flux dysregulation

There is clinical evidence to suggest that impaired myocardial glucose uptake contributes to the pathogenesis of hypertrophic, insulin-resistant cardiomyopathy. The goal of this study was to determine whether cardiac deficiency of the insulin-sensitive glucose transporter, GLUT4, has deleterious effect on cardiomyocyte excitation-contraction coupling. Cre-Lox mouse models of cardiac GLUT4 knockdown (KD, 85% reduction) and knockout (KO, > 95% reduction), which exhibit similar systemic hyperinsulinemic and hyperglycemic states, were investigated. The Ca²⁺ current (I_Ca) and Na⁺-Ca²⁺ exchanger (NCX) fluxes, Na⁺-H⁺ exchanger (NHE) activity, and contractile performance of GLUT4-deficient myocytes was examined using whole-cell patch-clamp, epifluorescence, and imaging techniques. GLUT4-KO exhibited significant cardiac enlargement characterized by cardiomyocyte hypertrophy (40% increase in cell area) and fibrosis. GLUT4-KO myocyte contractility was significantly diminished, with reduced mean maximum shortening (5.0 ± 0.4% vs. 6.2 ± 0.6%, 5 Hz). Maximal rates of shortening and relaxation were also reduced (20-25%), and latency was delayed. In GLUT4-KO myocytes, the I_Ca density was decreased (− 2.80 ± 0.29 vs. − 5.30 ± 0.70 pA/pF), and mean I_NCX was significantly increased in both outward (by 60%) and inward (by 100%) directions. GLUT4-KO expression levels of SERCA2 and RyR2 were reduced by approximately 50%. NHE-mediated H⁺ flux in response to NH₄Cl acid loading was markedly elevated GLUT4-KO myocytes, associated with doubled expression of NHE1. These findings demonstrate that, independent of systemic endocrinological disturbance, cardiac GLUT4 deficiency per se provides a lesion sufficient to induce profound alterations in cardiomyocyte Ca²⁺ and pH homeostasis. Our investigation identifies the cardiac GLUT4 as a potential primary molecular therapeutic target in ameliorating the functional deficits associated with insulin-resistant cardiomyopathy.     

神经肽Y对大鼠心肌细胞肌浆网钙的影响

目的观察神经肽Y（NPY）刺激对大鼠心肌细胞肌浆网（Sarcoplasmic Reticulum,SR）内钙含量的影响。方法用100nmol·L^-1NPY刺激Sprague-Dawley乳鼠心肌细胞24h,用荧光染料Fluo-4AM负载胞浆钙,并用咖啡因诱导的胞浆钙瞬变（Caffeine-induced Ca2＋ transient,CCT）幅度来反映肌浆网内总钙负荷;用荧光染料Fluo-5NAM直接标记心肌细胞肌浆网内游离钙离子。所有钙影像均由LeicaSP2激光共聚焦显微镜记录。结果经100nmol·L^-1NPY刺激24h后,心肌细胞肌浆网内游离钙含量明显低于对照组（p〈0.01）;咖啡因诱导下钙瞬变幅度也低于对照组。结论长时间的NPY刺激可导致肌浆网内钙含量减少。     

8-甲氧沙林对黑素细胞内游离钙浓度及细胞骨架蛋白形成的影响

目的:观察8-甲氧沙林对体外培养黑素细胞内游离钙浓度、细胞骨架蛋白形成的影响.方法:正常人黑素细胞取自包皮环切术切取的包皮,用激光共聚焦扫描显微镜检测细胞内游离钙浓度,用罗丹明结合毒伞素对细胞骨架蛋白进行特异性染色.结果:8-甲氧沙林可使细胞内游离钙离子浓度升高,促进黑素细胞骨架蛋白合成.结论:8-甲氧沙林可能通过诱导黑素细胞内钙离子浓度升高和细胞骨架actin蛋白生成,从而影响黑素细胞的迁移.