Centro de Fisiología y Medicina de Altura

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https://repositorioabierto.uantof.cl/handle/uantof/502

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Baroreflex and chemoreflex interaction in high-altitude exposure: possible role on exercise performance
(2024) Pablo Alvarez Araos; Sergio Jiménez; Camila Salazar Ardiles; Cristian Núñez Espinosa; Valeria Paez; Maria Rodriguez Fernandez; Antoine Raberin; Gregoire P. Millet; Rodrigo Iturriaga; David C. Andrade
The hypoxic chemoreflex and the arterial baroreflex are implicated in the ventilatory response to exercise. It is well known that long-term exercise training increases parasympathetic and decreases sympathetic tone, both processes influenced by the arterial baroreflex and hypoxic chemoreflex function. Hypobaric hypoxia (i.e., high altitude [HA]) markedly reduces exercise capacity associated with autonomic reflexes. Indeed, a reduced exercise capacity has been found, paralleled by a baroreflex-related parasympathetic withdrawal and a pronounced chemoreflex potentiation. Additionally, it is well known that the baroreflex and chemoreflex interact, and during activation by hypoxia, the chemoreflex is predominant over the baroreflex. Thus, the baroreflex function impairment may likely facilitate the exercise deterioration through the reduction of parasympathetic tone following acute HA exposure, secondary to the chemoreflex activation. Therefore, the main goal of this review is to describe the main physiological mechanisms controlling baro- and chemoreflex function and their role in exercise capacity during HA exposure.
Consequences of Exposure to Hypobaric Hypoxia Associated with High Altitude on Spermatogenesis and Seminal Parameters: A Literature Review
(2024) Carlos Cornejo Guerra; Camila Salazar Ardiles; Patricio Morales; David C. Andrade
Preclinical research has provided compelling evidence indicating that exposure to hypobaric hypoxia (HH) results in a deterioration of spermatogenesis. This adverse effect extends to the underlying molecular mechanisms, progressively leading to impairments in the seminiferous epithelium and germ cells and alterations in semen parameters. Indeed, several studies have demonstrated that animals exposed to HH, whether in natural high-altitude environments or under simulated hypoxic conditions, exhibit damage to the self-renewal and differentiation of spermatogenesis, an increase in germline cell apoptosis, and structural alterations in the seminiferous tubules. One of the primary mechanisms associated with the inhibition of differentiation and an increase in apoptosis among germ cells is an elevated level of oxidative stress, which has been closely associated with HH exposure. Human studies have shown that individuals exposed to HH, such as mountaineers and alpinists, exhibit decreased sperm count, reduced motility, diminished viability, and increased sperm with abnormal morphology in their semen. This evidence strongly suggests that exposure to HH may be considered a significant risk factor that could elevate the prevalence of male infertility. This literature review aims to provide a comprehensive description and propose potential mechanisms that could elucidate the infertility processes induced by HH. By doing so, it contributes to expanding our understanding of the challenges posed by extreme environments on human physiology, opening new avenues for research in this field.
Detraining’s Effects on Cardiorespiratory Fitness and Maximal and Explosive Strength in Army Soldiers: Does Age Matter?
(2024) Alexis Arce Álvarez; Ángelo Zaio; Camila Salazar Ardiles; Cristian Álvarez; Pablo Merino Muñoz; Manuel Vasquez-Muñoz; Mikel Izquierdo; Mauricio Castro; David C. Andrade
Purpose: This study investigated the impact of four weeks of age-dependent detraining on army soldiers’ cardiorespiratory fitness and maximal and explosive strength. Methods: Fourteen volunteer tactical athletes participated, divided into two age groups (20 to 29 and 30 to 40 years). Before and after the detraining period, we assessed their anthropometric measurements (weight, height, body mass index, fat mass, and fat-free mass), cardiorespiratory fitness (maximal oxygen uptake [VO2max] and ventilatory thresholds [VT1 and VT2]), and kinematic properties during a single-leg counter-moving jump (CMJ) test for both the dominant and non-dominant legs. Two-way ANOVA followed by the Holm–Sidak post hoc test was used. Results: The anthropometric and cardiovascular variables did not show significant differences between the groups. However, both groups exhibited a significantly reduced maximum time and speed at the VO2max. Furthermore, the flight time and maximum height during the CMJ significantly decreased in the non-dominant leg for both age groups. Notably, the dominant leg’s concentric impulse (CI) significantly reduced during the CMJ, but this effect was observed only in the 30–40 age group. There were significant differences between the two age groups. Conclusions: Our findings suggest that four weeks of detraining negatively impacts aerobic fitness and muscular strength, independently of age. However, the dominant leg may be more susceptible to detraining effects in army soldiers aged 30–40. Furthermore, as a perspective, our results strongly suggest that a detraining period could affect successful missions (aerobic performance deterioration), as well as promote a muscle imbalance between the legs, which could encourage muscle injuries and endanger combat missions.
Effect of chronic exogenous oxytocin administration on exercise performance and cardiovagal control in hypobaric hypoxia in rats
(2024) Camila Salazar Ardiles; Carlos Cornejo; Cristobal Paz; Manuel Vasquez Muñoz; Alexis Arce Alvarez; Maria Rodriguez Fernandez; Gregoire P. Millet; Mikel Izquierdo
Background Outstanding exercise performance has been associated with an exacerbated vagal outflow. Nevertheless, during high-altitude hypobaric-hypoxia (HH), there is a baroreflex-dependent parasympathetic withdrawal and exercise performance deterioration. Notably, vagal control is pivotal in exercise performance, and exogenous oxytocin (OXY) administration has been shown to enhance parasympathetic drive; however, no evidence shows their role in exercise performance during HH. Then, this study aimed to examine the effect of prolonged exogenous oxytocin (OXY) administration on exercise performance during hypobaric hypoxia (HH) in rats. Results A vehicle group (n = 6) and an OXY group (n = 6) performed incremental exercise and baroreflex tests during both normobaric normoxia (NN) and HH (PO2: 100 mmHg, simulated 3,500 m) prior (pre-) and after (post-) 14 days of administration. The results showed that at pre-, there were no significant differences in exercise performance between the two groups, while at post-, the OXY group exhibited similar performance between NN and HH, while the Vehicle group maintained a significant decline in performance at HH compared to NN. At post-, the Vehicle group also demonstrated a reset in the baroreflex and a worse bradycardic response in HH, which was reversed in the OXY group, while the hypoxic ventilatory response was similar in both groups. Conclusion The findings suggest prolonged OXY administration prevents impaired exercise performance and vagal control during short-term HH
Uncovering Hidden Microbial Diversity in Nitrate/Iodide Deposits (NIDs) in the Domeyko District, Atacama Desert, Chile
(2024) Mayra Cortés; Priscilla Avendaño; Olga Encalada; Camila Salazar Ardiles; David C. Andrade; Benito Gómez Silva; Daniel Contreras; Norman Toro; Dayana Arias; Lorena V. Escudero
Unique worldwide, nitrate/iodine deposits (NIDs) are located along a 700 km geological belt in the Atacama Desert, Chile. They serve as the primary source of mineral ores for the extraction of iodine, sodium, and potassium nitrates. NIDs have been relatively underexplored from a biological perspective. To address this, we collected sixteen soil samples from abandoned mines in Oficinas Pissis and Savona for chemical, mineralogical, and metagenomic analyses. The soils primarily consisted of halite and darapskite, with only one sample being predominantly composed of thenardite. Deliquescence and water activity measurements yielded values ranging from 0.02% to 0.40% and 0.47 to 0.62, respectively. To investigate the presence, identification, relative abundance, and diversity of microbial life in NID soils, we employed MiSeq high-throughput sequencing and bioinformatic tools. The dominant phyla observed were Firmicutes and Proteobacteria, with Actinobacteria and Cyanobacteria being predominant in two soil samples. Furthermore, we detected nitrate/perchloratereducing bacterial activity in enriched cultures from the soil samples. This study sheds light on the resilience of microbial life in the Atacama Desert NIDs, providing compelling evidence for its existence and offering insight into factors that could facilitate it within this unique environment.

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Examinando Centro de Fisiología y Medicina de Altura por Autor "Camila Salazar Ardiles"

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