NaX Channel Is a Physiological [Na+] Detector in Oxytocin- and Vasopressin-Releasing Magnocellular Neurosecretory Cells of the Rat Supraoptic Nucleus.

The Scn7A gene encodes NaX, an atypical noninactivating Na+ channel, whose expression in sensory circumventricular organs is essential to maintain homeostatic responses for body fluid balance. However, NaX has also been detected in homeostatic effector neurons, such as vasopressin (VP)-releasing magnocellular neurosecretory cells (MNCVP) that secrete VP (antidiuretic hormone) into the bloodstream in response to hypertonicity and hypernatremia. Yet, the physiological relevance of NaX expression in these effector cells remains unclear. Here, we show that rat MNCVP in males and females is depolarized and excited in proportion with isosmotic increases in [Na+]. These responses were caused by an inward current resulting from a cell-autonomous increase in Na+ conductance. The Na+-evoked current was unaffected by blockers of other Na+-permeable ion channels but was significantly reduced by shRNA-mediated knockdown of Scn7A expression. Furthermore, reducing the density of NaX channels selectively impaired the activation of MNCVP by systemic hypernatremia without affecting their responsiveness to hypertonicity in vivo These results identify NaX as a physiological Na+ sensor, whose expression in MNCVP contributes to the generation of homeostatic responses to hypernatremia.SIGNIFICANCE STATEMENT In this study, we provide the first direct evidence showing that the sodium-sensing channel encoded by the Scn7A gene (NaX) mediates cell-autonomous sodium detection by MNCs in the low millimolar range and that selectively reducing the expression of these channels in MNCs impairs their activation in response to a physiologically relevant sodium stimulus in vitro and in vivo These data reveal that NaX operates as a sodium sensor in these cells and that the endogenous sensory properties of osmoregulatory effector neurons contribute to their homeostatic activation in vivo.

The effect of passive ultrasonic activation of 2% chlorhexidine or 3% sodium hypochlorite in canal wall cleaning.

OBJECTIVES: the purpose of this study was to compare debris removal and open tubules effectiveness of sodium hypochlorite (NaOCl) and chlorhexidine (CHX) applied as final irrigation in different protocols Study Design: sixty extracted premolars were divided into six groups according to the final irrigation technique: A and B 3 % NaOCl or 2 % CHX with the Miraject needle and no agitation; C and D, passive ultrasonic irrigation (PUI) with Irrisafe 20 tips and 3 % NaOCl or 2 % CHX; E and F, PUI with Irrisafe 25 tips and 3 % NaOCl or 2% CHX. The remaining dentine debris and opened tubules were evaluated by SEM at three root levels by two blinded investigators. The Kruskal Wallis and the Mann-Whitney U test was used to compare groups and levels, with a significance of p<0.05. RESULTS: Debris elimination was significantly higher in PUI groups (p<0.05). PUI groups showed a higher capability to open tubules, compared to groups A and B. In the coronal third, groups D to F eliminated more debris and opened more tubules than conventional irrigation (p<0.05). In medium third, group E eliminated significantly more debris (1.60) than group A (2.60). No differences were obtained among groups in apical third. Both NaOCl and CHX applied with PUI showed no differences in debris elimination or opened tubules. CONCLUSIONS: Final PUI with Irrisafe tips was the most effective procedure for eliminating the debris and opening up dentinal tubules, independent of the irrigant solution or Irrisafe type size. Key words:Ultrasonic irrigation, PUI, sodium hypochlorite, chlorhexidine.

Effectiveness of passive ultrasonic irrigation in improving elimination of smear layer and opening dentinal tubules.

OBJECTIVE: To compare the ability to eliminate debris and open dentinal tubules of different ultrasound irrigation procedures. STUDY DESIGN: Forty extracted single-rooted human teeth were instrumented with mechanical rotatory instrumentation, and divided into four groups: (n=10) according to the final irrigation technique: group A (control), 2.5% NaOCl irrigation with the Miraject needle and no ultrasonic agitation; group B, passive ultrasonic irrigation (PUI) with 2.5% NaOCl and Irrisafe 20 tips; group C, PUI with 2.5% NaOCl and Irrisafe 25 tips; group D, PUI with 2.5% NaOCl and K 25 tips. The amount of debris and the number of opened dentinal tubules was established by scanning electronic microscope. Data were compared using the Kruskal Wallis test. RESULTS: Irrisafe tips (groups B and C) opened up more dentinal tubules and eliminated more debris than conventional irrigation (p<0.05) in the apical third. The middle third shows no significant differences between groups. Irrisafe 25 was more effective than conventional irrigation and K tips (p<0.05) in the coronal third. CONCLUSIONS: Ultrasonic activation of the irrigation with Irrisafe tips was the most effective procedure for eliminating the debris and opening up dentinal tubules, especially in the apical third. Key words:Pasive ultrasonic irrigation, irrigation, sodium hypochlorite.

Review of ultrasonic irrigation in endodontics: increasing action of irrigating solutions

Introduction: Effective irrigant delivery and agitation are prerequisites for successful endodontic treatment. Ultrasonic irrigation can be performed with or without simultaneous ultrasonic instrumentation. Existing literature reveals that ultrasonic irrigation may have a very positive effect on chemical, biological and physical debridement of the root canal system as investigated in many in vitro studies.Objective: The purpose of this review article was to summarize and discuss the available information concerning ultrasonic irrigation in endodontics. Methods: This article presents an overview of ultrasonic irrigation methods and their debridement efficacy. In this paper the relevant literature on passive ultrasonic irrigation is reviewed. Information from original scientific papers or reviews listed in MEDLINE and Cochrane were included in the review. Results: The use of ultrasound in the irrigation procedure results in improved canal cleanliness, better irrigant transfer to the canal system, soft tissue debridement, and removal of smear layer and bacteria. There are many in vitro studies, but there is a need to standardize protocols, and correlate the clinical efficacy of ultrasonic devices with improved treatment outcomes. Understanding the basis of ultrasonic irrigation is fundamental for clinicians and researchers to improve the design and use of ultrasonic irrigation (AU)

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Review of ultrasonic irrigation in endodontics: increasing action of irrigating solutions.

INTRODUCTION: Effective irrigant delivery and agitation are prerequisites for successful endodontic treatment. Ultrasonic irrigation can be performed with or without simultaneous ultrasonic instrumentation. Existing literature reveals that ultrasonic irrigation may have a very positive effect on chemical, biological and physical debridement of the root canal system as investigated in many in vitro studies. OBJECTIVE: The purpose of this review article was to summarize and discuss the available information concerning ultrasonic irrigation in endodontics. METHODS: This article presents an overview of ultrasonic irrigation methods and their debridement efficacy. In this paper the relevant literature on passive ultrasonic irrigation is reviewed. Information from original scientific papers or reviews listed in MEDLINE and Cochrane were included in the review. RESULTS: The use of ultrasound in the irrigation procedure results in improved canal cleanliness, better irrigant transfer to the canal system, soft tissue debridement, and removal of smear layers and bacteria. There are many in vitro studies, but there is a need to standardize protocols, and correlate the clinical efficacy of ultrasonic devices with improved treatment outcomes. Understanding the basis of ultrasonic irrigation is fundamental for clinicians and researchers to improve the design and use of ultrasonic irrigation.