Role of NaV1.7 in postganglionic sympathetic nerve function in human and guinea-pig arteries.

NaV1.7 plays a crucial role in inducing and conducting action potentials in pain-transducing sensory nociceptor fibres, suggesting that NaV1.7 blockers could be effective non-opioid analgesics. While SCN9A is expressed in both sensory and autonomic neurons, its functional role in the autonomic system remains less established. Our single neuron rt-PCR analysis revealed that 82% of sympathetic neurons isolated from guinea-pig stellate ganglia expressed NaV1.7 mRNA, with NaV1.3 being the only other tetrodotoxin-sensitive channel expressed in approximately 50% of neurons. We investigated the role of NaV1.7 in conducting action potentials in postganglionic sympathetic nerves and in the sympathetic adrenergic contractions of blood vessels using selective NaV1.7 inhibitors. Two highly selective NaV1.7 blockers, GNE8493 and PF 05089771, significantly inhibited postganglionic compound action potentials by approximately 70% (P < 0.01), with residual activity being blocked by the NaV1.3 inhibitor, ICA 121431. Electrical field stimulation (EFS) induced rapid contractions in guinea-pig isolated aorta, pulmonary arteries, and human isolated pulmonary arteries via stimulation of intrinsic nerves, which were inhibited by prazosin or the NaV1 blocker tetrodotoxin. Our results demonstrated that blocking NaV1.7 with GNE8493, PF 05089771, or ST2262 abolished or strongly inhibited sympathetic adrenergic responses in guinea-pigs and human vascular smooth muscle. These findings support the hypothesis that pharmacologically inhibiting NaV1.7 could potentially reduce sympathetic and parasympathetic function in specific vascular beds and airways. KEY POINTS: 82% of sympathetic neurons isolated from the stellate ganglion predominantly express NaV1.7 mRNA. NaV1.7 blockers inhibit action potential conduction in postganglionic sympathetic nerves. NaV1.7 blockade substantially inhibits sympathetic nerve-mediated adrenergic contractions in human and guinea-pig blood vessels. Pharmacologically blocking NaV1.7 profoundly affects sympathetic and parasympathetic responses in addition to sensory fibres, prompting exploration into the broader physiological consequences of NaV1.7 mutations on autonomic nerve activity.

Disparities in the association between ambient temperature and preterm birth according to individual and regional characteristics: a nationwide time-stratified case-crossover study.

BACKGROUND: Several studies have reported that climate change elevates heat exposure in pregnant women and high temperatures during pregnancy are associated with preterm births (PTBs). Although the association might be disproportionate, related evidence remains sparse. We evaluated the disproportionate risk of PTB associated with ambient temperature during pregnancy by individual and regional characteristics in South Korea. METHODS: We collected data on birth certificates and daily mean temperatures during the period from 2011 to 2019. A time-stratified case-crossover design was used to investigate the association between temperature and PTB and stratified analyses were conducted to examine the effect modification of individual and regional characteristics. RESULTS: A total of 160,067 singleton PTBs were recorded in Korea from 2011 to 2019. A 5℃ increase in the mean temperature during the last four weeks before delivery was associated with an increased risk of PTB with an odds ratio (OR) of 1.03 (95% confidence interval [CI]: 1.02, 1.05), and the association was more evident in mothers aged ≥35 years (OR: 1.06 [95% CI: 1.03, 1.10]) and with low education levels (OR: 1.04 [95% CI: 1.02, 1.05]). Additionally, the estimated risk was evident in districts with lower medical resources and more prominent disparities were shown by individual and regional characteristics in rural areas than in urban areas. CONCLUSIONS: This study provides evidence that the risk of PTB related to ambient temperature is disproportionate by individual and regional characteristics and suggests the need for public health policies to alleviate the disparities, especially in rural areas.

Role of NaV 1.9 in inflammatory mediator-induced activation of mouse airway vagal C-fibres.

The influence of NaV 1.9 on inflammatory mediator-induced activation of airway vagal nodose C-fibres was evaluated by comparing responses in wild-type versus NaV 1.9-/- mice. A single-cell RT-PCR analysis indicated that virtually all nodose C-fibre neurons expressed NaV 1.9 (SCN11A) mRNA. Using extracellular electrophysiological recordings in an isolated vagally innervated mouse trachea-lung preparation, it was noted that mediators acting via G protein-coupled receptors (PAR2), or ionotropic receptors (P2×3) were 70-85% less effective in evoking action potential discharge in the absence of NaV 1.9. However, there was no difference in action potential discharge between wild-type and NaV 1.9-/- when the stimulus was a rapid punctate mechanical stimulus. An analysis of the passive and active properties of isolated nodose neurons revealed no difference between neurons from wild-type and NaV 1.9-/- mice, with the exception of a modest difference in the duration of the afterhyperpolarization. There was also no difference in the amount of current required to evoke action potentials (rheobase) or the action potential voltage threshold. The inward current evoked by the chemical mediator by a P2×3 agonist was the same in wild-type versus NaV 1.9-/- neurons. However, the current was sufficient to evoke action potential only in the wild-type neurons. The data support the speculation that NaV 1.9 could be an attractive therapeutic target for inflammatory airway disease by selectively inhibiting inflammatory mediator-associated vagal C-fibre activation. KEY POINTS: Inflammatory mediators were much less effective in activating the terminals of vagal airway C-fibres in mice lacking NaV 1.9. The active and passive properties of nodose neurons were the same between wild-type neurons and NaV 1.9-/- neurons. Nerves lacking NaV 1.9 responded, normally, with action potential discharge to rapid punctate mechanical stimulation of the terminals or the rapid stimulation of the cell bodies with inward current injections. NaV 1.9 channels could be an attractive target to selectively inhibit vagal nociceptive C-fibre activation evoked by inflammatory mediators without blocking the nerves' responses to the potentially hazardous stimuli associated with aspiration.

Amycolatopsis from Desert Specialist Fungus-Growing Ants Suppresses Contaminant Fungi Using the Antibiotic ECO-0501.

Symbiotic Actinobacteria help fungus-growing ants suppress fungal pathogens through the production of antifungal compounds. Trachymyrmex ants of the southwest desert of the United States inhabit a unique niche far from the tropical rainforests in which most fungus-growing ant species are found. These ants may not encounter the specialist fungal pathogen Escovopsis known to threaten colonies of other fungus-growing ants. It is unknown whether Actinobacteria associated with these ants antagonize contaminant fungi and, if so, what the chemical basis of such antagonism is. We find that Pseudonocardia and Amycolatopsis strains isolated from three desert specialist Trachymyrmex species do antagonize diverse contaminant fungi isolated from field-collected ant colonies. We did not isolate the specialist fungal pathogen Escovopsis in our sampling. We trace strong antifungal activity from Amycolatopsis isolates to the molecule ECO-0501, an antibiotic that was previously under preclinical development as an antibacterial agent. In addition to suppression of contaminant fungi, we find that this molecule has strong activity against ant-associated Actinobacteria and may also play a role in bacterial competition in this niche. By studying interspecies interactions in a previously unexplored niche, we have uncovered novel bioactivity for a structurally unique antibiotic. IMPORTANCE Animal hosts often benefit from chemical defenses provided by microbes. These molecular defenses are a potential source of novel antibiotics and offer opportunities for understanding how antibiotics are used in ecological contexts with defined interspecies interactions. Here, we recover contaminant fungi from nests of Trachymyrmex fungus-growing ants of the southwest desert of the United States and find that they are suppressed by Actinobacteria isolated from these ants. The antibiotic ECO-0501 is an antifungal agent used by some of these Amycolatopsis bacterial isolates. This antibiotic was previously investigated in preclinical studies and known only for antibacterial activity.

The role of vascular surgeons in the management of pediatric bone tumors.

OBJECTIVES: The objective of this study was to review the outcomes of a multidisciplinary approach to the surgical management of pediatric bone tumors with blood vessel involvement over a 14- year period. METHODS: A retrospective review was conducted of all pediatric bone tumor resections performed with the assistance of vascular surgery at our institution between January 2006 and January 2021. Inclusion criteria for the study included the presence of a vascular surgeon at the operative resection and radiographic evidence of major blood vessel involvement. RESULTS: From 2006 to 2021, 117 patients underwent a bone tumor resection by a single orthopedic surgeon/vascular surgeon team. Sixty were malignant tumors, and 57 were benign. Of the 117 procedures, 5.1% (6/117) required reconstruction of an artery; five in malignant cases and one in benign. No venous reconstructions were undertaken in this study. Ligation of a major artery without reconstruction was performed in 8.8% (5/57) of malignant and 1.7% (1/60) of benign resections. Despite this vessel-sparing approach, microscopic margins were clear in all cases. Local recurrence occurred in a single patient in the malignant group at 61 months. CONCLUSIONS: The ideal management of pediatric bone tumors with major blood vessel involvement remains poorly defined. Our results demonstrate that even in the setting of radiographic evidence of vessel involvement, a multidisciplinary team of vascular and orthopedic surgeons can employ a vessel-sparing approach with minimal blood loss, excellent limb salvage, and minimal local recurrence.

Serotonin-Mediated Activation of Serotonin Receptor Type 1 Oppositely Modulates Voltage-Gated Calcium Channel Currents in Rat Sensory Neurons Innervating Hindlimb Muscle.

Serotonin (5-HT) is a multifaceted neurotransmitter that has been described to play a role as a peripheral inflammatory mediator when released in ischemic or injured muscle. Dorsal root ganglia (DRG) neurons are key sensors of noxious stimuli that are released under inflammatory conditions or mechanical stress. Little information is available on the specific 5-HT receptor subtypes expressed in primary afferents that help regulate reflex pressor responses. In the present study, the whole-cell patch-clamp technique was employed to examine the modulation of voltage-gated calcium channel (CaV) 2.2 currents by 5-HT and to identify the 5-HT receptor subtype(s) mediating this response in acutely dissociated rat DRG neurons innervating triceps surae muscle. Our results indicate that exposure of 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI)-labeled DRG neurons to 5-HT can exert three modulatory effects on CaV currents: high inhibition, low inhibition, and enhancement. Both 5-HT-mediated inhibition responses were blocked after pretreatment with pertussis toxin (PTX), indicating that 5-HT receptors are coupled to CaV2.2 via Gα i/o protein subunits. Application of selective serotonin receptor type 1 (5-HT1) agonists revealed that modulation of CaV2.2 currents occurs primarily after 5-HT1A receptor subtype stimulation and minimally from 5-HT1D activation. Finally, the intrathecal administration of the selective 5-HT1A receptor agonist, 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT), significantly (P < 0.05) decreased the pressor response induced by intra-arterial administration of lactic acid. This suggests that 5-HT1A receptors are expressed presynaptically on primary afferent neurons innervating triceps surae muscle. Our findings indicate that preferential stimulation of 5-HT1 receptors, expressed on thin fiber muscle afferents, serves to regulate the reflex pressor response to metabolic stimuli. SIGNIFICANCE STATEMENT: The monoamine serotonin (5-HT), released under ischemic conditions, can contribute to the development of inflammation that negatively affects the exercise pressor reflex. The 5-HT receptor subtype and signaling pathway that underlies calcium channel modulation in dorsal root ganglia afferents, innervating hindlimb muscles, are unknown. We show that 5-HT can either block (primarily via serotonin receptor type 1 (5-HT1)A subtypes) or enhance voltage-gated calcium channel (CaV2.2) currents. Our findings suggest 5-HT exhibits receptor subtype selectivity, providing a complexity of cellular responses.

Total body skin exams: the role of gynecology and dermatology-a cross-sectional study.

The literature demonstrates practice gaps in performance of the genital skin examination. To further elucidate and understand these practice gaps, we surveyed dermatologist and obstetrician-gynecologist (OB/GYN) attending and resident physicians. Analysis of 73 dermatology survey responses revealed a lack of satisfaction with training received in examination of the female genitalia. Moreover, examination of 69 OB/GYN survey responses showed a lack of satisfaction with residency training received to identify high risk skin lesions. Interestingly, only 52.2% of OB/GYN respondents inspect perianal skin during pelvic region examinations. Our results highlight the need to improve residency training through standardization of breast/genitalia skin examinations during both dermatology and OB/GYN residency and for increased collaboration between specialties.

A proposed model for a comprehensive virtual subinternship in vascular surgery.

OBJECTIVE: In the present study, we sought to understand the challenges, advantages, and applications of a vascular surgery virtual subinternship (VSI) curriculum. METHODS: Our institution hosted 25 students for two 4-week VSI rotations, one in July 2020 and one in August 2020. The students participated in a curriculum centered around the use of Zoom and telephone interactions with residents and faculty. The curriculum included selected readings, surgical videos, group didactics, and one-on-one mentorship. Anonymous pre- and postrotation self-assessments were used to ascertain the students' achievement of the learning objectives and the utility of the educational tools implemented during the rotation. The faculty and resident mentors were also surveyed to assess their experience. RESULTS: With the exception of knot-tying techniques (P = .67), the students reported significant improvement in their understanding of vascular surgery concepts after the virtual elective (P < .05). The highest ranked components of the course were interpersonal, including interaction with faculty, mentorship, and learning the program culture. The lowest ranked components of the course were simulation training and research opportunities. The rating of the utility of aspects of the course were consistent with the ranking of the components, with faculty interaction receiving the highest average rating. The ideal amount of time for daily virtual interaction reported by the students ranged from 3 to 6 hours (median, 4 hours). Overall, most of the mentors were satisfied with the virtual course. However, they reported limited ability to assess the students' personality and fit for the program. The time spent per week by the mentors on the virtual vascular surgery rotation ranged from 2 to 7 hours (median, 4 hours). Of the 17 mentors completing the surveys, 14 reported that having a virtual student was a significant addition to their existing workload. CONCLUSIONS: Overall, our student and mentor feedback was positive. Several challenges inherent to the virtual environment still require refinement. However, the goals of a VSI are distinct and should be explored by training programs. With changes to healthcare in the United States on the horizon and the constraints resulting from the severe acute respiratory syndrome coronavirus 2 pandemic, implementing a virtual away rotation could be an acceptable platform in our adaptations of our recruitment strategies.

Utilizing functional lumen imaging probe in directing treatment for post-fundoplication dysphagia.

BACKGROUND: Esophagogastric junction obstruction (EGJO) post-fundoplication (PF) is difficult to identify with currently available tests. We aimed to assess the diagnostic accuracy of EGJ opening on functional lumen imaging probe (FLIP) and dilation outcome in FLIP-detected EGJO in PF dysphagia. METHODS: We prospectively collected data on PF patients referred to Esophageal Clinic over 18 months. EGJO diagnosis was made by (a) endoscopist's description of a narrow EGJ/wrap area, (b) appearance of wrap obstruction or contrast/tablet retention on esophagram, or (c) EGJ-distensibility index (DI) < 2.8 mm2/mmHg on real-time FLIP. In patients with EGJO and dysphagia, EGJ dilation was performed to 20 mm, 30 mm, or 35 mm in a stepwise fashion. Outcome was assessed as % dysphagia improvement during phone call or on brief esophageal dysphagia questionnaire (BEDQ) score. RESULTS: Twenty-six patients were included, of whom 17 (65%) had a low EGJ-DI. No patients had a hiatal hernia greater than 3 cm. Dysphagia was the primary symptom in 17/26 (65%). In 85% (κ = 0.677) of cases, EGJ assessment (tight vs. open) was congruent between the combination of endoscopy (n = 26) and esophagram (n = 21) vs. EGJ-DI (n = 26) on FLIP. Follow-up data were available in 11 patients who had dilation based on a low EGJ-DI (4 with 20 mm balloon and 7 with ≥ 30 mm balloon). Overall, the mean % improvement in dysphagia was 60% (95% CI 37.7-82.3%, p = 0.0001). Nine out of 11 patients, including 6 out of 7 undergoing pneumatic dilation, had improvement ≥ 50% in dysphagia (mean % improvement 72.2%; 95% CI 56.1-88.4%, p = 0.0001). CONCLUSIONS AND INFERENCES: Functional lumen imaging probe is an accurate modality for evaluating for EGJ obstruction PF. FLIP may be used to select patients who may benefit from larger diameter dilation.

Functional knockout of ASIC3 attenuates the exercise pressor reflex in decerebrated rats with ligated femoral arteries.

The exercise pressor reflex arises from contracting muscle and is manifested by increases in arterial pressure, heart rate, and cardiac contractility. In patients with peripheral artery disease, the exercise pressor reflex is exaggerated. This effect is believed to be caused by a metabolite whose concentration is increased when the working muscles are inadequately perfused. Previous work in rats with simulated peripheral artery disease has shown that pharmacological blockade of acid-sensing ion channel 3 (ASIC3), which is found on group III and IV afferents, prevented the exaggeration of the exercise pressor reflex. Blockade of ASIC3, however, may have off-target effects that preclude a conclusion that ASIC3 plays a role in evoking the reflex in rats with simulated peripheral artery disease. In the present experiments performed in decerebrated rats with simulated peripheral artery disease, we compared the exercise pressor reflex in rats with a functional knockout of the ASIC3 (KO) with the reflex in their wild-type counterparts (WT). We found that the exercise pressor reflex in ASIC3 KO rats was significantly lower than the exercise pressor reflex in their WT counterparts (P < 0.05). ASIC 3 KO rats demonstrated lower pressor responses to intra-arterial injection of diprotonated phosphate (86 mM; pH 6.0), lactic acid (12 mM; pH 2.85), and capsaicin (0.2 µg; pH 7.2) (P < 0.05). In contrast, both ligated WT and ASIC3 KO rats displayed similar pressor responses to tendon stretch (P > 0.05). We conclude that ASIC3 play an important role in evoking the exaggerated exercise pressor reflex in rats with peripheral artery disease.NEW & NOTEWORTHY We used a genetic approach to test the hypothesis that the magnitude of the exercise pressor reflex evoked in ligated ASIC3 KO rats was significantly lower than the magnitude of the exercise pressor reflex evoked in their ligated wild-type (WT) counterparts. The pressor response to contraction in ligated ASIC3 KO rats was significantly smaller than was the pressor response to contraction in ligated WT rats.

ASIC1a does not play a role in evoking the metabolic component of the exercise pressor reflex in a rat model of peripheral artery disease.

The role of the ASIC1a in evoking the exercise pressor reflex in rats with simulated peripheral artery disease is unknown. This prompted us to determine whether ASIC1a plays a role in evoking the exaggerated exercise pressor reflex in decerebrated rats with simulated peripheral artery disease. To simulate peripheral artery disease, we ligated the left femoral artery 72 h before the experiment. The right femoral artery was freely perfused and used as a control. To test our hypothesis, we measured the effect of injecting two ASIC1a blockers into the arterial supply of the triceps surae muscles with and without the femoral artery ligated on the reflex pressor responses to 1) static contraction of the triceps surae muscles, 2) calcaneal tendon stretch, and 3) intra-arterial injection of diprotonated phosphate (pH 6.0). We found that the ASIC1a blockers psalmotoxin-1 (200 ng/kg) and mambalgin-1 (6.5 µg/kg) decreased the pressor responses to static contraction as well as the peak pressor responses to injection of diprotonated phosphate when these responses were evoked from the freely perfused hindlimb. In contrast, ASIC1a blockers only decreased the peak pressor responses evoked by injection of diprotonated phosphate in the hindlimb circulation with simulated peripheral artery disease. This inhibitory effect was less than the one measured from the healthy hindlimb. Independently of the hindlimb of interest, ASIC1a blockers had no effect on the pressor responses to tendon stretch. Our results do not support the hypothesis that ASIC1a play a role in evoking the exercise pressor reflex arising from a hindlimb with simulated peripheral artery disease.NEW & NOTEWORTHY The role of ASIC1a in evoking the metabolic component of the exercise pressor reflex in peripheral artery disease is unknown. Using a within-rat experimental design, we found that the contribution of ASIC1a decreased in a rat model of peripheral artery disease. These results have key implications to help finding better treatments and improve morbidity, quality of life, and mortality in patients with peripheral artery disease.

ASIC1a plays a key role in evoking the metabolic component of the exercise pressor reflex in rats.

The role of the acid-sensing ion channel 1a (ASIC1a) in evoking the exercise pressor reflex is unknown, despite the fact that ASIC1a is opened by decreases in pH in the physiological range. This fact prompted us to test the hypothesis that ASIC1a plays an important role in evoking the exercise pressor reflex in decerebrated rats with freely perfused hindlimb muscles. To test this hypothesis, we measured the effect of injecting two ASIC1a blockers into the arterial supply of the triceps surae muscles on the reflex pressor responses to four maneuvers, namely 1) static contraction of the triceps surae muscles (i.e., the exercise pressor reflex), 2) calcaneal tendon stretch, 3) intra-arterial injection of lactic acid, and 4) intra-arterial injection of diprotonated phosphate. We found that the 2 ASIC1a blockers, psalmotoxin-1 (200 ng/kg) and mambalgin-1 (6.5 µg/kg), decreased the pressor responses to static contraction as well as the peak pressor responses to injection of lactic acid and diprotonated phosphate. In contrast, neither ASIC1a blocker had any effect on the pressor responses to tendon stretch. Importantly, we found that ASIC1a blockade significantly decreased the pressor response to static contraction after a latency of at least 8 s. Our results support the hypothesis that ASIC1a plays a key role in evoking the metabolic component of the exercise pressor reflex.NEW & NOTEWORTHY The role played by acid-sensing ion channel 1a (ASIC1a) in evoking the exercise pressor reflex remains unknown. In decerebrated rats with freely perfused femoral arteries, blocking ASIC1a with psalmotoxin-1 or mambalgin-1 significantly attenuated the pressor response to static contraction, lactic acid, and diprotonated phosphate injection but had no effect on the pressor response to stretch. We conclude that ASIC1a plays a key role in evoking the exercise pressor reflex by responding to contraction-induced metabolites, such as protons.

Intrathecal injection of brilliant blue G, a P2X7 antagonist, attenuates the exercise pressor reflex in rats.

Purinergic 2X (P2X) receptors on the endings of group III and IV afferents play a role in evoking the exercise pressor reflex. Particular attention has been paid to P2X3 receptors because their blockade in the periphery attenuated this reflex. In contrast, nothing is known about the role played by P2X receptors in the spinal cord in evoking the exercise pressor reflex in rats. P2X7 receptors, in particular, may be especially important in this regard because they are found in abundance on spinal glial cells and may communicate with neurons to effect reflexes controlling cardiovascular function. Consequently, we investigated the role played by spinal P2X7 receptors in evoking the exercise pressor reflex in decerebrated rats. We found that intrathecal injection of the P2X7 antagonist brilliant blue G (BBG) attenuated the exercise pressor reflex (blood pressure index: 294 ± 112 mmHg·s before vs. 7 ± 32 mmHg·s after; P < 0.05). Likewise, intrathecal injection of minocycline, which inhibits microglial cell output, attenuated the reflex. In contrast, intrathecal injection of BBG did not attenuate the pressor response evoked by intracarotid injection of sodium cyanide, a maneuver that stimulated carotid chemoreceptors. Moreover, injections of BBG either into the arterial supply of the contracting hindlimb muscles or into the jugular vein did not attenuate the exercise pressor reflex. Our findings support the hypothesis that P2X7 receptors on microglial cells within the spinal cord play a role in evoking the exercise pressor reflex.

Rare presentation of adult-onset cutaneous mastocytoma of the breast.

Mastocytosis is a rare condition in which mast cells accumulate throughout various organs of the body-the most common subtype being confined to the skin. We present an unusual case of cutaneous mastocytosis localized to the unilateral breast of a young woman with partial involvement of the areola. Previously diagnosed as nipple eczema, the patient failed appropriate treatment with class III and IV topical corticosteroids. Given it was adult onset, failed appropriate treatment, and had an atypical clinical appearance, a biopsy was pursued that revealed mastocytosis in skin. This is another clinical diagnosis dermatologists may consider in their differential diagnosis of nipple dermatitis.

Impact of the NaV1.8 variant, A1073V, on post-sigmoidectomy pain and electrophysiological function in rat sympathetic neurons.

NaV1.8 channels play a crucial role in regulating the action potential in nociceptive neurons. A single nucleotide polymorphism in the human NaV1.8 gene SCN10A, A1073V (rs6795970, G>A), has been linked to the diminution of mechanical pain sensation as well as cardiac conduction abnormalities. Furthermore, studies have suggested that this polymorphism may result in a "loss-of-function" phenotype. In the present study, we performed genomic analysis of A1073V polymorphism presence in a cohort of patients undergoing sigmoid colectomy who provided information regarding perioperative pain and analgesic use. Homozygous carriers reported significantly reduced severity in postoperative abdominal pain compared with heterozygous and wild-type carriers. Homozygotes also trended toward using less analgesic/opiates during the postoperative period. We also heterologously expressed the wild-type and A1073V variant in rat superior cervical ganglion neurons. Electrophysiological testing demonstrated that the mutant NaV1.8 channels activated at more depolarized potentials compared with wild-type channels. Our study revealed that postoperative abdominal pain is diminished in homozygous carriers of A1073V and that this is likely due to reduced transmission of action potentials in nociceptive neurons. Our findings reinforce the importance of NaV1.8 and the A1073V polymorphism to pain perception. This information could be used to develop new predictive tools to optimize patient pain experience and analgesic use in the perioperative setting.NEW & NOTEWORTHY We present evidence that in a cohort of patients undergoing sigmoid colectomy, those homozygous for the NaV1.8 polymorphism (rs6795970) reported significantly lower abdominal pain scores than individuals with the homozygous wild-type or heterozygous genotype. In vitro electrophysiological recordings also suggest that the mutant NaV1.8 channel activates at more depolarizing potentials than the wild-type Na+ channel, characteristic of hypoactivity. This is the first report linking the rs6795970 mutation with postoperative abdominal pain in humans.

Stimulation of spinal δ-opioid receptors attenuates the exercise pressor reflex in decerebrate rats.

A reflex arising from contracting hindlimb muscle is responsible in part for the increases in arterial pressure and heart rate evoked by exercise. The afferent arm of this reflex comprises group III and IV afferents. δ-Opioid receptors are expressed predominately on the spinal endings of group III afferents, whereas µ-opioid receptors are expressed predominately on the spinal endings of group IV afferents. Using stimuli that activated group III afferents, namely static contraction, calcaneal tendon stretch, and lactic acid injection into the superficial epigastric artery, we tested the hypothesis that, in rats with either patent or ligated femoral arteries, activation of pre- and postsynaptic δ-opioid receptors in the dorsal horn attenuated pressor reflex responses to these stimuli. In rats with patent arteries or ligated femoral arteries, [d-Pen2,5]enkephalin (DPDPE), a δ-opioid agonist injected intrathecally (10 µg in 10 µl), significantly attenuated the pressor responses to contraction, stretch, and lactic acid (all P < 0.05). Naltrindole, a δ-opioid receptor antagonist, prevented the attenuation. In contrast, DPDPE did not attenuate the pressor response to capsaicin injection into the superficial epigastric artery in either group of rats (both P > 0.05). Intrathecal injection of saline (10 µl), the vehicle for DPDPE, had no effect on the pressor responses in either group of rats. We conclude that activation of spinal δ-opioid receptors attenuates reflexes evoked by group III afferents in both freely perfused and ligated rats.

Effect of knockout of the ASIC3 on cardiovascular reflexes arising from hindlimb muscle in decerebrated rats.

The exercise pressor reflex is initiated by the contraction-induced activation of group III and IV muscle afferents. The reflex is manifested by increases in arterial blood pressure and cardiac output, which, in turn, are generated by increases in the sympathetic outflow to the heart and vasculature and decreases in the vagal outflow to the heart. In previous experiments, we used a pharmacological approach to assess the role played by the acid-sensing ion channel 3 (ASIC3) on group III and IV afferents in evoking the exercise pressor reflex. In the present experiments, we used an alternative approach, namely functional knockout (KO) of the ASIC3 gene, to confirm and extend our previous finding that pharmacological blockade of the ASIC3 had only a small impact on the expression of the exercise pressor reflex when the arterial supply to the contracting hindlimb muscles of rats was patent. Using this alternative approach, we compared the magnitude of the exercise pressor reflex evoked in ASIC3 KO rats with that evoked in their wild-type (WT) counterparts. We found both WT and ASIC3 KO rats displayed similar pressor responses to static contraction (WT, n = 10, +12 ± 2 mmHg; KO, n = 9, +11 ± 2 mmHg) and calcaneal tendon stretch (WT, n = 9, +13 ± 2 mmHg; KO, n = 7, +11 ± 2 mmHg). Likewise, both WT and ASIC3 KO displayed similar pressor responses to intra-arterial injection of 12 mM lactic acid (WT, n = 9, +14 ± 3 mmHg; KO, n = 8, +18 ± 5 mmHg), 24 mM lactic acid (WT, n = 9,+24 ± 2 mmHg; KO, n = 8, +20 ± 5 mmHg), capsaicin (WT, n = 9,+27 ± 5 mmHg; KO, n = 10, +29 ± 5 mmHg), and diprotonated phosphate ([Formula: see text]; WT, n = 6,+22 ± 3 mmHg; KO, n = 6, +32 ± 6 mmHg). We conclude that redundant receptors are responsible for evoking the pressor reflexes arising from group III and IV afferents.

Blocking the transient receptor potential vanilloid-1 does not reduce the exercise pressor reflex in healthy rats.

Controversy exists regarding the role played by transient receptor potential vanilloid-1 (TRPV1) in evoking the exercise pressor reflex. Here, we determine the role played by TRPV1 in evoking this reflex while assessing possible confounding factors arising from TRPV1 antagonists or from the vehicle in which they were dissolved. The exercise pressor reflex was evoked in decerebrated, anesthetized Sprague-Dawley rats by electrical stimulation of the tibial nerve to contract the triceps surae muscles statically. This procedure was repeated before and after injection of the TRPV1 blockers: capsazepine (100 µg/100 µL), ruthenium red (100 µg/100 µL), or iodoresiniferatoxin (IRTX; 1 µg/100 µL). We found that capsazepine decreased the exercise pressor reflex when the drug was dissolved in DMSO (-10 ± 9 mmHg; P = 0.015; n = 7). However, similar reduction was found when DMSO alone was injected (-8 ± 5 mmHg; P = 0.023; n = 5). Capsazepine, dissolved in ethanol (2 ± 6 mmHg; P = 0.49; n = 7), ruthenium red (-4 ± 12 mmHg; P = 0.41; n = 7), or IRTX (4 ± 18 mmHg; P = 0.56; n = 7), did not significantly decrease the exercise pressor reflex. In addition, we found that capsazepine and ruthenium red had "off-target" effects. Capsazepine decreased the pressor response evoked by intra-arterial injection of bradykinin (500 ng/kg; -12 ± 13 mmHg; P = 0.028; n = 9) and α-ß-methylene ATP (10 µg/kg; -7 ± 8 mmHg; P = 0.019; n = 10), whereas ruthenium red decreased the ability of the muscle to produce and sustain force (-99 ± 83 g; P = 0.020; n = 7). Our data therefore suggest that TRPV1 does not play a role in evoking the exercise pressor reflex. Additionally, given their strong off-target effects, capsazepine and ruthenium red should not be used for studying the role played by TRPV1 in evoking the exercise pressor reflex.

Awareness of the New Kidney Allocation System among United States Dialysis Providers with Low Waitlisting.

It is unknown whether dialysis facility staff are aware of the new kidney allocation system implemented in December 2014, which changed how deceased donor kidneys are allocated and waiting time is calculated. U.S. dialysis facilities with low annual waitlisting (<15.2%) were surveyed as part of a large randomized study. Among 653 facilities, 57.9% of staff were aware of the policy change, with medical directors (84.4%) being more aware than social workers (73.3%), facility administrators (53.1%), nurse managers (46.4%), and other staff (43.8%). Targeted education among dialysis facilities with low waitlisting may help extend the reach of the new policy.