Commonly used intravenous anesthetics decrease bladder contractility: An in vitro study of the effects of propofol, ketamine, and midazolam on the rat bladder

Molecular mechanisms of cholinergic neurotransmission in visceral smooth muscles with a focus on receptor-operated TRPC4 channel and impairment of gastrointestinal motility by general anaesthetics and anxiolytics

Acetylcholine is the primary excitatory neurotransmitter in visceral smooth muscles, wherein it binds to and activates two muscarinic receptors subtypes, M2 and M3, thus causing smooth muscle excitation and contraction. The first part of this review focuses on the types of cells involved in cholinergic neurotransmission and on the molecular mechanisms underlying acetylcholine-induced membrane depolarisation, which is the central event of excitation-contraction coupling causing Ca2+ entry via L-type Ca2+ channels and smooth muscle contraction. Studies of the muscarinic cation current in intestinal myocytes (mICAT) revealed its main molecular counterpart, receptor-operated TRPC4 channel, which is activated in synergy by both M2 and M3 receptors. M3 receptors activation is of permissive nature, while activation of M2 receptors via Gi/o proteins that are coupled to them plays a direct role in TRPC4 opening. Our understanding of signalling pathways underlying mICAT generation has vastly expanded in recent years through studies of TRPC4 gating in native cells and its regulation in heterologous cells. Recent studies using muscarinic receptor knockout have established that at low agonist concentration activation of both M2 receptor and the M2/M3 receptor complex elicits smooth muscle contraction, while at high agonist concentration M3 receptor function becomes dominant. Based on this knowledge, in the second part of this review we discuss the cellular and molecular mechanisms underlying the numerous anticholinergic effects on neuroactive drugs, in particular general anaesthetics and anxiolytics, which can significantly impair gastrointestinal motility. This article is part of the Special Issue on "Ukrainian Neuroscience".

Preoperative Videourodynamic Study Is Helpful in Predicting Long-term Postoperative Voiding Function in Asymptomatic Patients With Closed Spinal Dysraphism

Purpose

Controversy exists regarding the role preoperative urodynamic study for asymptomatic closed spinal dysraphism as it has failed to reveal the benefit in surgical decision and expectation of urological outcomes. We explore the relationship between preoperative videourodynamic study and postoperative urological outcomes after toilet training completed, focusing on their capability of spontaneous voiding.

Methods

We retrospectively reviewed the data of 181 patients who underwent preventive spinal cord untethering and followed at least till the completion of toilet training. Before untethering, patients underwent preoperative videourodynamic study. Postoperative voiding function was evaluated in 3 phases: (1) till postoperative 6 months, (2) till the completion of toilet training, and (3) 2 years after toilet training. Changing distribution of emptying pattern at each period was described. Also, relevance to preoperative urodynamic parameters on spontaneous voiding and urinary continence after toilet training was assessed.

Results

Spinal lipoma and low lying conus were found in 145 (80%) and 128 patients (70.7%), respectively. Spontaneous voiding was found in 125 (69.1%), 164 (90.6%), and 162 patients (89.5%) at postoperative 6 months, till the toilet training, and 2 years after toilet training, respectively. Videourodynamics helped to clarify the presence of vesicourethral synergy. This was correlated with spontaneous voiding at postoperative 6 months and better urinary continence after 2 years of toilet training.

Conclusions

Eventual spontaneous voiding was achieved till toilet training in 90% patients following preventive untethering. Those showing preoperative vesicourethral synergy was associated with faster achievement of spontaneous voiding and better urinary continence when they enter elementary school.

Validation of a new rat model of urethral sphincter injury and leak point pressure measurements

AIMS

In vivo experiments were performed to establish and validate a rat model of urethral sphincter injury and to develop a method for leak point pressure (LPP) measurements performed repeatedly in the same animal.

METHODS

Twenty-four Sprague-Dawley female rats underwent bladder and epidural catheter implantation. Five days later, cystometry was performed using continuous infusion. Anesthesia with isoflurane, ketamine-xylazine (KX) or fentanyl-fluanisone-midazolam (FFM) was used. After three micturition cycles, intrathecal bupivacaine was administered leading to the suppression of reflex bladder contractions. LPP measurements were performed using vertical tilt. After the initial LPP measurement, animals underwent partial resection of the striated urethral sphincter. The effect was evaluated 6 weeks after surgery, by repeating the LPP measurement in the same animal.

RESULTS

Ten out of 19 animals showed full micturition cycles under isoflurane, and all 9 animals under KX anesthesia. No significant difference in micturition pressures (Mean ± SEM; 30.1 ± 2.3 vs. 26.8 ± 1.6 mmHg) and LPP (31.0 ± 2.4 vs. 28.0 ± 0.9 mmHg) was observed between isoflurane and KX groups, respectively. Reflex micturition was suppressed with FFM. Bupivacaine led to overflow incontinence in all cases. Sphincter injury caused fibrotic changes and a significant increase in LPP (26.4 ± 2.3 before vs. 46.9 ± 4.6 mmHg after injury, p < 0.05).

CONCLUSIONS

KX anesthesia preserves bladder contractions. Intrathecal bupivacaine eliminates reflex micturition, allowing for repeated LPP measurements in the same animal. Resection of striated sphincter resulted in increased LPP 6 weeks post injury. The site of urethral sphincter resection healed with fibrosis.

Molecular pathways underlying tissue injuries in the bladder with ketamine cystitis

Ketamine cystitis (KC) is a chronic bladder inflammation leading to urinary urgency, frequency, and pain. The pathogenesis of KC is complicated and involves multiple tissue injuries in the bladder. Recent studies indicated that urothelium disruption, lamina propria fibrosis and inflammation, microvascular injury, neuropathological alterations, and bladder smooth muscle (BSM) abnormalities all contribute to the pathogenesis of KC. Ketamine has been shown to induce these tissue injuries by regulating different signaling pathways. Ketamine can stimulate antiproliferative factor, adenosine triphosphate, and oxidative stress to disrupt urothelium. Lamina propria fibrosis and inflammation are associated with the activation of cyclooxygenase-2, nitric oxide synthase, immunoglobulin E, and transforming growth factor β1. Ketamine contributes to microvascular injury via the N-methyl-D aspartic receptor (NMDAR), and multiple inflammatory and angiogenic factors such as tumor necrosis factor α and vascular endothelial growth factor. For BSM abnormalities, ketamine can depress the protein kinase B, extracellular signal-regulated kinase, Cav1.2, and muscarinic receptor signaling. Elevated purinergic signaling also plays a role in BSM abnormalities. In addition, ketamine affects neuropathological alterations in the bladder by regulating NMDAR- and brain-derived neurotrophic factor-dependent signaling. Inflammatory cells also contribute to neuropathological changes via the secretion of chemical mediators. Clarifying the role and function of these signaling underlying tissue injuries in the bladder with KC can contribute to a better understanding of the pathophysiology of this disease and to the design of effective treatments for KC.

Anesthetic protocols for urodynamic studies of the lower urinary tract in small rodents-A systematic review

Urodynamic studies in rats and mice are broadly used to examine pathomechnisms of disease and identify and test therapeutic targets. This review aims to highlight the effects of the anesthetics on the lower urinary tract function and seeks to identify protocols that allow recovery from anesthesia and repeated measurements while preserving the function which is being studied. All studies published in English language, which compared the data obtained under various types of anesthesia and the urodynamics performed in awake animals were included. It appears that urethane, an anesthetic recommended extensively for the investigation of lower urinary tract function, is appropriate for acute urodynamic studies only. Major advantages of urethane are its stability and ability to preserve the micturition reflex. Due to its toxicity and carcinogenicity, urethane anesthesia should not be used for recovery procedures. This review evaluated available alternatives including propofol, isoflurane and combinations of urethane, ketamine/xylazine, ketamine/medetomidine, and/or fentanyl/fluanisone/midazolam. Different effects have been demonstrated among these drugs on the urinary bladder, the urethral sphincter, as well as on their neuroregulation. The lowest incidence of adverse effects was observed with the use of a combination of ketamine and xylazine. Although the variations in the reviewed study protocols represent a limitation, we believe that this summary will help in standardizing and optimizing future experiments.

Evaluation of the effects of sedation administered via three different routes on the procedure, child and parent satisfaction during cystometry

Purpose

In this study, we retrospectively investigated case reports with and without midazolam administration via oral, intranasal and rectal before cystometry procedure. We aimed to compare the data to evaluate the effects of sedation before cystometry on the pediatric patients and parents’ satisfaction.

Methods

A total of 124 ASA I-II pediatric cases aged 5–14 years were retrospectively investigated from the hospital records. One of the three administration routes was chosen; oral midazolam at a dose of 0.5 mg/kg and nasal or rectal midazolam at a dose of 0.3 mg/kg (maximum 15 mg). Heart rate, blood pressure, oxygen saturation, the Wisconsin Hospital of Children Sedation Scale (CHWSS) score and the Groningen Distress Rating Scale (GDRS) score were recorded. Cystometry measurement values, diagnoses of the cases and procedure durations were recorded from the urodynamic laboratory records.

Results

80 female, 44 male cases were evaluated. The CHWSS score at the 10th and 20th minutes after the drug administeration was higher in the oral group than the others (p = 0.001). The duration between the administration of the drug and the start of the procedure was shorter in the nasal group (p = 0.01). Parents satisfaction for sedation was 77 % when comparison of the cystometry with and without sedation. Comparison of the cystometry results with or without sedation no significant difference was found between all parameters (p > 0.01).

Conclusion

We believe that sedation with midazolam administered through all three routes is a safe, effective and convenient option during cystometry, especially in the young age group.