Effect of stimulation intensity and botulinum toxin isoform on rat bladder strip contractions

The present experiments compared the inhibitory effects of botulinum toxin A (BoNT-A) and botulinum toxin D (BoNT-D) on neurally evoked contractions of rat bladder strips. We examined the effect of fatigue (trains of 100 shocks at 20Hz every 20s for 10min) followed by non-fatigue stimulation (trains of 100 shocks at 20Hz every 100s for 20min) on the onset of effect and potency of the two toxins. For non-fatigue experiments, strips were untreated (n=4); or incubated with 1.36nM BoNT-A (n=4). During fatigue experiments, strips were untreated (n=5); or treated with either 1.36nM BoNT-A (n=6) or 0.8nM BoNT-D (n=6). In non-fatigue experiments, BoNT-A produced significant decreases in contractile area after 1h of stimulation compared to untreated strips (P<0.05). After three series of fatigue stimulation, differences in recovery amplitude and area between untreated versus BoNT-A, and untreated versus BoNT-D bladder strips, were statistically significant (P<0.05). The onset of inhibitory effect was quicker in BoNT-D-treated strips, as a significant reduction (P<0.05) in recovery of contractile area was observed after 1h of stimulation compared to both untreated and BoNT-A-treated preparations. In addition, treated (BoNT-A and BoNT-D) and untreated bladder strips responded similarly to atropine, suggesting that the effects of BoNT result from inhibition of both acetylcholine and ATP release. Our results demonstrate that BoNT-D may be a more effective agent to inhibit transmitter release from autonomic nerves of the rat lower urinary tract. Moreover, in our hands, non-fatigue stimulation is as effective as fatigue stimulation in inhibiting bladder strip contractions.     

Synergistic effect of human relaxin and progesterone on human myometrial contractions

In an in vitro human myometrial strip system, both relaxin and progesterone can independently decrease the amplitude of spontaneous myometrial contractions. However, progesterone and relaxin synergize in this action. Doses of relaxin and progesterone which independently are ineffective, together inhibit myometrial contraction amplitude. Relaxin and progesterone are both products of the corpus luteum, a structure necessary for early pregnancy maintenance. The synergistic action of relaxin and progesterone in vitro suggests a similar in vivo physiologic effect in establishing uterine quiescence.     

肌成纤维细胞在创面收缩中的作用

目的：研究肌成纤维细胞在创面收缩过程中的作用，探讨创面收缩机理。方法：对兔耳及背部创面进行创面收缩观察并用电镜、免疫组化等方法对比研究肌成纤维细胞出现及变化规律。结果：肌成纤维细胞出现的时间晚于创面收缩时间，出现的量与创面收缩的程度关系密切。结论；肌成纤维细胞不是创面收缩的始动因素，但参与了创面收缩过程。     

Effects of the mycotoxin destruxin A on Locusta migratoria visceral muscles

Destruxins, a family of cyclic peptides, are produced by various species of entomopathogenic fungi. These peptides have been shown to influence calcium-dependent processes in insect cell lines and tissues, such as skeletal muscles. To better understand the mechanism of action of these peptide toxins on insect muscular tissues, we have evaluated the effects of destruxin A on the contractions of oviducts and hindgut of Locusta migratoria. In oviducts, destruxin A increased the frequency of spontaneous contractions and induced a dose-dependent tonic contraction; the EC₅₀ for lower lateral and upper lateral oviducts was 0.7 μM and 8.7 μM, respectively. In hindgut, destruxin A also caused an increase in the frequency of spontaneous contractions; the EC₅₀ was 3.2 μM. The action of destruxin A was abolished in Ca²⁺-free saline or when the Ca²⁺ channel blocker CoCl₂ was added to the incubation saline. Likewise, the presence of 50 μM nifedipine or 100 μM verapamil in the medium reduced the magnitude of destruxin A′s effect, particularly in hindgut. The depolarization of muscle membranes by 100 mM K⁺ saline prevented the action of destruxin A. Preincubation of lower lateral oviducts in the intracellular Ca²⁺ antagonist TMB-8 did not have any effect on destruxin A action; however, preincubation in the calmodulin inhibitor trifluoperazine greatly reduced the effect of destruxin A. Taken together, these results show that destruxin A has an excitatory effect on contractions of insect visceral muscles of L. migratoria. Destruxin A-induced contractions appear to be dependent on extracellular, but not on intracellularly-released Ca²⁺, which suggest that this peptide toxin might be acting on insect visceral muscle by facilitating an influx of extracellular Ca²⁺.     

Endothelium-independent relaxation and contraction of rat aorta induced by ethyl acetate extract from leaves of Morus alba (L.)

Aim of the study

Based on screening for vasoactive traditional Chinese medicinal herbs, the present study was performed to investigate the vasoactive effects of an ethyl acetate extract from leaves of Morus alba (L.) (ELM) on rat thoracic aorta and the mechanisms underlying these effects.

Materials and methods

Isolated rat thoracic rings were mounted in an organ bath system and the effects of ELM on their responses were evaluated.

Results

ELM (0.125–32.000 g/l) induced a concentration-dependent relaxation (P < 0.01 vs. control) both in endothelium-intact and -denuded aortas precontracted by high K⁺ (6 × 10⁻² M) or 10⁻⁶ M phenylephrine (PE). In endothelium-denuded aortas, ELM at the EC₅₀ concentration reduced Ca²⁺-induced contraction (P < 0.01 vs. control) after PE or KCl had generated a stable contraction in Ca²⁺-free solution. And after incubation with verapamil, ELM induced contraction in endothelium-denuded aortas precontracted by PE (P < 0.01 vs. control); this was abolished by ruthenium red (P < 0.01 vs. ELM-treated endothelium-denuded group; P > 0.05 vs. control), but not by heparin (P > 0.01 vs. ELM-treated endothelium-denuded group; P < 0.01 vs. control).

Conclusions

The results showed that ELM had dual vasoactive effects, and the relaxation was greater than the contraction. The relaxation was mediated by inhibition of voltage- and receptor-dependent Ca²⁺ channels in vascular smooth muscle cells, while the contraction occurred via activation of ryanodine receptors in the sarcoplasmic reticulum.     

定量组织速度成像评价模拟失重人体心肌纵向收缩运动

目的应用定量组织速度成像(QTVI)了解中长期微重力对健康人左室心肌纵向收缩运动的影响,探讨QTVI技术评价模拟失重环境下心肌运动的应用价值。方法16名健康青年男性志愿者,采取-6°头低位连续卧床21d,分别于卧前、卧中第10、20d行心脏超声检查,应用QTVI获取心尖四腔、两腔和左室长轴观图像存储后脱机测量,同步观察左室壁各段心肌纵向收缩速度峰值(Vs),进行统计学分析。结果-6°头低位卧床第10、20d分别与卧前Vs比较:第10d左室前、后壁的基底段、中间段及前间隔各节段增高,而下壁和后间隔近心尖段减低,第20d下壁和后间隔近心尖段继续减低,而后壁、前间隔近心尖段仍高于卧前,差异均具有统计学意义。结论QTVI能够反映微重力环境左室心肌局部收缩运动情况,Vs值有助于进一步了解模拟失重、失重环境下左室心肌收缩运动的变化过程。     

Phospholipase C mediated Ca signals in murine urinary bladder smooth muscle

Muscarinic stimulation of urinary bladder induces contraction via an increase in intracellular Ca²⁺ concentration that results from Ca²⁺ influx through Ca²⁺ channels and/or IP₃-mediated Ca²⁺ release controlled by phospholipase C (PLC) signalling. The significance of PLC/IP₃ signalling in this cascade has recently been questioned because PLC inhibitors were without effect on carbachol-induced contractions in detrusor muscle strips. However, PLC/IP₃-mediated Ca²⁺ release was clearly observed in recordings of Ca²⁺ signals in isolated myocytes. Therefore, we investigated the presence of PLC/IP₃-dependent Ca²⁺ release by directly monitoring Ca²⁺ signals in intact detrusor muscle strips. Concomitant Ca²⁺ signals from Ca²⁺ channel activity were eliminated by the Ca²⁺ channel antagonist isradipine (3 µM) or by the use of muscles from Ca_v1.2 channel-deficient (SMACKO) mice. In absence of Ca²⁺ channel activity, carbachol elicited contractions and Ca²⁺ signals in muscles from wild type and SMACKO mice that were inhibited by the PLC inhibitor U73122 (10 µM). The results show that PLC/IP₃-dependent Ca²⁺ release is activated by stimulation with carbachol in urinary bladder smooth muscle but has a minor contribution to overall carbachol-induced Ca²⁺ signals.     

Rapid closure of midgestational excisional wounds in a fetal mouse model is associated with altered transforming growth factor-β isoform and receptor expression

Background

Many pediatric diseases are characterized by excessive tissue contraction. Because of a poor understanding of contraction, few therapies exist. We developed a murine fetal excisional wound model of contraction and theorize that wound closure is associated with changes in transforming growth factor-β (TGF-β) expression.

Methods

Pregnant FVB mice underwent hysterotomy at midgestational (E15) or late-gestational (E18) ages. Three-millimeter excisional wounds were made in fetuses and harvested at 32 hours. Real-time polymerase chain reaction was performed for TGF-β1, TGF-β2, TGF-β3, TβR-1, and TβR-2 in wounds and normal skin and normalized to glyceraldehyde-3-phosphate dehydrogenase. Data were analyzed by paired t test (P < .05). H&E staining of wounds was performed.

Results

E15 wounds (80.5% ± 4.4%) were smaller than E18 wounds (10.4% ± 10.5%; P < .001) at 32 hours. E15 wounds expressed higher levels of TGF-β1 compared with normal skin (P = .001). TβR-2 levels were elevated in E15 and E18 wounds compared with their respective normal skin (P = .02, P = .01) and in E18 normal skin compared with E15 normal skin (P = .002).

Conclusion

This study demonstrates that rapid midgestational wound closure in a murine model is associated with increased TGF-β1 and TβR-2 expression. Elucidating the role of the TGF-β pathways may lead to an improved understanding of wound contraction.     

晚期产后出血48例临床分析

目的探讨晚期产后出血的病因及防治措施。方法回顾性分析48例晚期产后出血的病因及处理。结果主要病因依次为胎盘、胎膜残留、蜕膜残留和（或）子宫内膜炎,子宫复旧全以及剖宫产术的子宫切口愈合不良等。结论治疗以清官为主,加宫缩剂止血剂,积极抗炎,对反复出血或急性大出血可行子宫切除术。