American journal of physiology. Regulatory, integrative and comparative physiology最新文献

{"title":"Glutamatergic and purinergic transmitters and astrocyte modulation in the synaptic transmission in the NTS of rats exposed to short-term sustained hypoxia.","authors":"Darlan S Bazilio, Davi J A Moraes, Benedito H Machado","doi":"10.1152/ajpregu.00293.2023","DOIUrl":"10.1152/ajpregu.00293.2023","url":null,"abstract":"<p><p>There is evidence that astrocytes modulate synaptic transmission in the nucleus tractus solitarius (NTS) interacting with glutamatergic and purinergic mechanisms. Here, using in situ working heart-brainstem preparations, we evaluated the involvement of astrocyte and glutamatergic/purinergic neurotransmission in the processing of autonomic and respiratory pathways in the NTS of control and rats exposed to sustained hypoxia (SH). Baseline autonomic and respiratory activities and the responses to chemoreflex activation (KCN) were evaluated before and after microinjections of fluorocitrate (FCt, an astrocyte metabolic inhibitor), kynurenic acid, and pyridoxalphosphate-6-azophenyl-2',4'-disulfonate (PPADS) (nonselective antagonists of glutamatergic and purinergic receptors) into the rostral aspect of the caudal commissural NTS. FCt had no effects on the baseline parameters evaluated but reduced the bradycardic response to chemoreflex activation in SH rats. FCt combined with kynurenic acid and PPADS in control rats reduced the baseline duration of expiration, which was attenuated after SH. FCt produced a large increase in PN frequency discharge in control rats, which was reduced after SH, indicating a reduction in the astrocyte modulation after SH. The data show that <i>1</i>) the bradycardic component of the peripheral chemoreflex is reduced in SH rats after astrocytes inhibition, <i>2</i>) the inhibition of astrocytes in the presence of double antagonists in the NTS affects the modulation of baseline duration of expiration in control but not in SH rats, and <i>3</i>) the autonomic and respiratory responses to chemoreflex activation are mediated by glutamatergic and purinergic receptors in the rostral aspect of the caudal commissural NTS.<b>NEW & NOTEWORTHY</b> Our findings indicate that the neurotransmission of autonomic and respiratory components of the peripheral chemoreflex in the nucleus tractus solitarius (NTS) is mediated by glutamatergic and purinergic mechanisms and reveal a selective involvement of NTS astrocytes in controlling the chemoreflex parasympathetic response in rats exposed to sustained hypoxia (SH) and the baseline duration of expiration mainly in control rats, indicating a selective role for astrocytes modulation in the NTS of control and SH rats.</p>","PeriodicalId":7630,"journal":{"name":"American journal of physiology. Regulatory, integrative and comparative physiology","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141892633","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of endogenous and exogenous hormones on the cardiovascular response to lower extremity exercise and group III/IV activation in young females.","authors":"Ninitha Asirvatham-Jeyaraj, Miguel Anselmo, Daniel P Chantigian, Mia Larson, Emma J Lee, Manda L Keller-Ross","doi":"10.1152/ajpregu.00017.2024","DOIUrl":"10.1152/ajpregu.00017.2024","url":null,"abstract":"<p><p>Oral contraceptive (OC) use can increase resting blood pressure (BP) in females as well as contribute to greater activation of group III/IV afferents during upper body exercise. It is unknown, however, whether an exaggerated BP response occurs during lower limb exercise in OC users. We sought to elucidate the group III/IV afferent activity-mediated BP and heart rate responses while performing lower extremity tasks during early and late follicular phases in young, healthy females. Females not taking OCs (NOC: <i>n</i> = 8; age: 25 ± 4 yr) and those taking OCs (OC: <i>n</i> = 10; age: 23 ± 2 yr) completed a continuous knee extension/flexion passive stretch (mechanoreflex) and cycling exercise with subsystolic cuff occlusion (exercise pressor reflex), which was followed by a 2-min postexercise circulatory occlusion (PECO) (metaboreflex). Data collection occurred on two occasions: once during the early follicular phase (<i>days 1-4</i>) and once during the late follicular phase (<i>days 10-14</i>) of their menstrual cycle (NOC) or during the placebo and active pill phases (OC). Resting mean arterial BP and heart rate were not different between phases in NOC and OC participants (<i>P</i> > 0.05). Hemodynamic responses to metaboreflex, mechanoreflex, and collective exercise pressor reflex activation were not different between phases in both groups (<i>P</i> > 0.05). In conclusion, although OCs are known to increase BP at rest, our findings indicate that neither endogenous nor exogenous (OC) sex hormones modulate BP during large, lower limb muscle exercise with or without group III/IV afferent activation in young, healthy females.<b>NEW & NOTEWORTHY</b> Sex differences in the cardiovascular response to exercise have been demonstrated and may be dependent on sex hormone levels. Furthermore, oral contraceptives (OCs) have been shown to exaggerate the blood pressure response to upper extremity exercise. The results of this study indicate that neither endogenous nor exogenous (OC) sex hormones modulate BP during lower extremity dynamic exercise or with group III/IV afferent activation in young, healthy females.</p>","PeriodicalId":7630,"journal":{"name":"American journal of physiology. Regulatory, integrative and comparative physiology","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11483072/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141733318","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of sodium bicarbonate ingestion on ventilatory and cerebrovascular responses in resting heated humans.","authors":"Akira Katagiri, Naoto Fujii, Kohei Dobashi, Yin-Feng Lai, Bun Tsuji, Takeshi Nishiyasu","doi":"10.1152/ajpregu.00161.2024","DOIUrl":"10.1152/ajpregu.00161.2024","url":null,"abstract":"<p><p>Hyperthermia stimulates ventilation in humans. This hyperthermia-induced hyperventilation may be mediated by the activation of peripheral chemoreceptors implicated in the regulation of respiration in reaction to various chemical stimuli, including reductions in arterial pH. Here, we investigated the hypothesis that during passive heating at rest, the increases in arterial pH achieved with sodium bicarbonate ingestion, which could attenuate peripheral chemoreceptor activity, mitigate hyperthermia-induced hyperventilation. We also assessed the effect of sodium bicarbonate ingestion on cerebral blood flow responses, which are associated with hyperthermia-induced hyperventilation. Twelve healthy men ingested sodium bicarbonate (0.3 g/kg body weight) or sodium chloride (0.208 g/kg). One hundred minutes after the ingestion, the participants were passively heated using hot-water immersion (42°C) combined with a water-perfused suit. Increases in esophageal temperature (an index of core temperature) and minute ventilation (V̇_E) during the heating were similar in the two trials. Moreover, when V̇_E is expressed as a function of esophageal temperature, there were no between-trial differences in the core temperature threshold for hyperventilation (38.0 ± 0.3 vs. 38.0 ± 0.4°C, <i>P</i> = 0.469) and sensitivity of hyperthermia-induced hyperventilation as assessed by the slope of the core temperature-V̇_E relation (13.5 ± 14.2 vs. 15.8 ± 15.5 L/min/°C, <i>P</i> = 0.831). Furthermore, middle cerebral artery mean blood velocity (an index of cerebral blood flow) decreased similarly with heating duration in both trials. These results suggest that sodium bicarbonate ingestion does not mitigate hyperthermia-induced hyperventilation and the reductions in cerebral blood flow index in resting heated humans.<b>NEW & NOTEWORTHY</b> Hyperthermia leads to hyperventilation and associated cerebral hypoperfusion, both of which may impair heat tolerance. This hyperthermia-induced hyperventilation may be mediated by peripheral chemoreceptors, which can be activated by reductions in arterial pH. However, our results suggest that sodium bicarbonate ingestion, which can increase arterial pH, is not an effective intervention in alleviating hyperthermia-induced hyperventilation and cerebral hypoperfusion in resting heated humans.</p>","PeriodicalId":7630,"journal":{"name":"American journal of physiology. Regulatory, integrative and comparative physiology","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141892632","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Salinity and prolactin regulate anoctamin 1 in the model teleost, Fundulus heteroclitus","authors":"Jason P. Breves, Mariana A. Posada, Yixuan T. Tao, Ciaran A. Shaughnessy","doi":"10.1152/ajpregu.00188.2024","DOIUrl":"https://doi.org/10.1152/ajpregu.00188.2024","url":null,"abstract":"American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, Ahead of Print. <br/>","PeriodicalId":7630,"journal":{"name":"American journal of physiology. Regulatory, integrative and comparative physiology","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142196840","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Pre-workout Dietary Nitrate Magnifies Training-induced Benefits to Physical Function in Late Postmenopausal Women: A Randomized Pilot Study","authors":"Stephen J. Carter, Tyler H. Blechschmid, Marissa N. Baranauskas, Emily B. Long, Allison H. Gruber, John S. Raglin, Kenneth Lim, Andrew R. Coggan","doi":"10.1152/ajpregu.00150.2024","DOIUrl":"https://doi.org/10.1152/ajpregu.00150.2024","url":null,"abstract":"American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, Ahead of Print. <br/>","PeriodicalId":7630,"journal":{"name":"American journal of physiology. Regulatory, integrative and comparative physiology","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142196843","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Consideration of absolute intensity when examining sex differences in blood pressure responses during static exercise","authors":"Jordan B. Lee, Philip J. Millar","doi":"10.1152/ajpregu.00152.2024","DOIUrl":"https://doi.org/10.1152/ajpregu.00152.2024","url":null,"abstract":"American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, Ahead of Print. <br/>","PeriodicalId":7630,"journal":{"name":"American journal of physiology. Regulatory, integrative and comparative physiology","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142196842","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mitragynine and Morphine Produce Dose-dependent Bimodal Action on Food but not Water Intake in Rats","authors":"Julio D. Zuarth Gonzalez, Marco Mottinelli, Christopher R. McCurdy, Guillaume de Lartigue, Lance R. McMahon, Jenny L. Wilkerson","doi":"10.1152/ajpregu.00128.2024","DOIUrl":"https://doi.org/10.1152/ajpregu.00128.2024","url":null,"abstract":"American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, Ahead of Print. <br/>","PeriodicalId":7630,"journal":{"name":"American journal of physiology. Regulatory, integrative and comparative physiology","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142196841","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Neuroprotection provided by hypothermia initiated with high transnasal flow with ambient air in a model of pediatric cardiac arrest.","authors":"Zeng-Jin Yang, C Danielle Hopkins, Polan T Santos, Shawn Adams, Ewa Kulikowicz, Jennifer K Lee, Harikrishna Tandri, Raymond C Koehler","doi":"10.1152/ajpregu.00078.2024","DOIUrl":"10.1152/ajpregu.00078.2024","url":null,"abstract":"<p><p>Clinical trials of hypothermia after pediatric cardiac arrest (CA) have not seen robust improvement in functional outcome, possibly because of the long delay in achieving target temperature. Previous work in infant piglets showed that high nasal airflow, which induces evaporative cooling in the nasal mucosa, reduced regional brain temperature uniformly in half the time needed to reduce body temperature. Here, we evaluated whether initiation of hypothermia with high transnasal airflow provides neuroprotection without adverse effects in the setting of asphyxic CA. Anesthetized piglets underwent sham-operated procedures (<i>n</i> = 7) or asphyxic CA with normothermic recovery (38.5°C; <i>n</i> = 9) or hypothermia initiated by surface cooling at 10 (<i>n</i> = 8) or 120 (<i>n</i> = 7) min or transnasal cooling initiated at 10 (<i>n</i> = 7) or 120 (<i>n</i> = 7) min after resuscitation. Hypothermia was sustained at 34°C with surface cooling until 20 h followed by 6 h of rewarming. At 4 days of recovery, significant neuronal loss occurred in putamen and sensorimotor cortex. Transnasal cooling initiated at 10 min significantly rescued the number of viable neurons in putamen, whereas levels in putamen in other hypothermic groups remained less than sham levels. In sensorimotor cortex, neuronal viability in the four hypothermic groups was not significantly different from the sham group. These results demonstrate that early initiation of high transnasal airflow in a pediatric CA model is effective in protecting vulnerable brain regions. Because of its simplicity, portability, and low cost, transnasal cooling potentially could be deployed in the field or emergency room for early initiation of brain cooling after pediatric CA.<b>NEW & NOTEWORTHY</b> The onset of therapeutic hypothermia after cardiac resuscitation is often delayed, leading to incomplete neuroprotection. In an infant swine model of asphyxic cardiac arrest, initiation of high transnasal airflow to maximize nasal evaporative cooling produced hypothermia sufficient to provide neuroprotection that was not inferior to body surface cooling. Because of its simplicity and portability, this technique may be of use in the field or emergency room for rapid brain cooling in pediatric cardiac arrest victims.</p>","PeriodicalId":7630,"journal":{"name":"American journal of physiology. Regulatory, integrative and comparative physiology","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11444505/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141299821","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The multidrug resistance protein 4 is expressed and functionally active in isolated bladder from pig.","authors":"Erick de Toledo Gomes, Gabriela Reolon Passos, Natalícia de Jesus Antunes, Mariana Gonçalves de Oliveira, Valeria Barbosa de Souza, André Almeida Schenka, José Luiz da Costa, Edson Antunes, Fabiola Zakia Mónica","doi":"10.1152/ajpregu.00238.2023","DOIUrl":"10.1152/ajpregu.00238.2023","url":null,"abstract":"<p><p>Multidrug resistance proteins type 4 (MRP4) and 5 (MRP5) play pivotal roles in the transport of cyclic nucleotides in various tissues. However, their specific functions within the lower urinary tract remain relatively unexplored. This study aimed to investigate the effect of pharmacological inhibition of MRPs on cyclic nucleotide signaling in isolated pig bladder. The relaxation responses of the bladder were assessed in the presence of the MRP inhibitor, MK571. The temporal changes in intra- and extracellular levels of cAMP and cGMP in stimulated tissues were determined by mass spectrometry. The gene (<i>ABCC4</i>) and protein (MRP4) expression were also determined. MK571 administration resulted in a modest relaxation effect of approximately 26% in carbachol-precontracted bladders. The relaxation induced by phosphodiesterase inhibitors such as cilostazol, tadalafil, and sildenafil was significantly potentiated in the presence of MK571. In contrast, no significant potentiation was observed in the relaxation induced by substances elevating cAMP levels or stimulators of soluble guanylate cyclase. Following forskolin stimulation, both intracellular and extracellular cAMP concentrations increased by approximately 15.8-fold and 12-fold, respectively. Similarly, stimulation with tadalafil + BAY 41-2272 resulted in roughly 8.2-fold and 3.4-fold increases in intracellular and extracellular cGMP concentrations, respectively. The presence of MK571 reduced only the extracellular levels of cGMP. This study reveals the presence and function of MRP4 transporters within the porcine bladder and paves the way for future research exploring the role of this transporter in both underactive and overactive bladder disorders.<b>NEW & NOTEWORTHY</b> This study investigates the impact of pharmacological inhibition of MRP4 and MRP5 transporters on cyclic nucleotide signaling in isolated pig bladders. MK571 administration led to modest relaxation, with enhanced effects observed in the presence of phosphodiesterase inhibitors. However, substances elevating cAMP levels remained unaffected. MK571 selectively reduced extracellular cGMP levels. These findings shed light on the role of MRP4 transporters in the porcine bladder, opening avenues for further research into bladder disorders.</p>","PeriodicalId":7630,"journal":{"name":"American journal of physiology. Regulatory, integrative and comparative physiology","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141330219","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Sex differences in heat stress vulnerability among middle-aged and older adults (PSU HEAT Project).","authors":"Olivia K Leach, Rachel M Cottle, Kat G Fisher, S Tony Wolf, W Larry Kenney","doi":"10.1152/ajpregu.00114.2024","DOIUrl":"10.1152/ajpregu.00114.2024","url":null,"abstract":"<p><p>Individuals over the age of 65 yr are the most vulnerable population during severe environmental heat events, experiencing worse health outcomes than any other age cohort. The risk is greater in older women than in age-matched men; however, whether that reflects a greater susceptibility to heat in women, or simply population sex proportionality, is unclear. Seventy-two participants (29 M/43 F) aged 40-92 yr were exposed to progressive heat stress at a metabolic rate designed to reflect activities of daily living. Experiments were conducted in both hot-dry (HD; up to 53°C; ≤25% rh) and warm-humid (WH; ∼35°C; ≥50% rh) environments. After critical limits were determined for each condition, forward stepwise multiple linear regression analyses were conducted with net metabolic rate (M_net) and age entered into the model first, followed by sex, body mass (m_b), maximal oxygen consumption (V̇o_2max), body surface area, and LDL cholesterol. After accounting for M_net and age, sex further improved the regression model in the HD environment ([Formula: see text] = 0.34, <i>P</i> < 0.001) and the WH environment ([Formula: see text] = 0.36, <i>P</i> < 0.005). Sex explained ∼15% of the variance in critical environmental limits in HD conditions and 12% in WH conditions. Heat compensability curves were shifted leftward for older women, indicating age- and sex-dependent heat vulnerability compared with middle-aged women and older men in WH (<i>P</i> = 0.007, <i>P</i> = 0.03) and HD (<i>P</i> = 0.001, <i>P</i> = 0.01) environments. This reflects the heterogeneity of thermal-balance thresholds associated with aging relative to those seen in young adults and suggests that older females are more vulnerable than their age-matched male counterparts.<b>NEW & NOTEWORTHY</b> In contrast to young adults, there are sex differences in critical environmental limits in middle-aged and older adults. Older women exhibit lower critical environmental limits in both humid and dry extreme environments demonstrated by a leftward shift in heat compensability curves. These data confirm a true sex difference in heat vulnerability of older adults and support the epidemiological mortality data from environmental heat waves.</p>","PeriodicalId":7630,"journal":{"name":"American journal of physiology. Regulatory, integrative and comparative physiology","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11444510/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141615758","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}