Current research in physiology最新文献

{"title":"Metabolic dysfunctions promoted by AIN-93G standard diet compared with three obesity-inducing diets in C57BL/6J mice","authors":"Lais Marinho Aguiar ,&nbsp;Carolina Soares de Moura ,&nbsp;Cintia Reis Ballard ,&nbsp;Aline Rissetti Roquetto ,&nbsp;Juliana Kelly da Silva Maia ,&nbsp;Gustavo H.B. Duarte ,&nbsp;Larissa Bastos Eloy da Costa ,&nbsp;Adriana Souza Torsoni ,&nbsp;Jaime Amaya-Farfan ,&nbsp;Mário R. Maróstica Junior ,&nbsp;Cinthia Baú Betim Cazarin","doi":"10.1016/j.crphys.2022.11.001","DOIUrl":"10.1016/j.crphys.2022.11.001","url":null,"abstract":"<div><p>Researchers from different fields have studied the causes of obesity and associated comorbidities, proposing ways to prevent and treat this condition by using a common animal model of obesity to create a profound energy imbalance in young adult rodents. However, to confirm the harmful effects of consuming a high-fat and hypercaloric diet, it is common to include normolipidic and normocaloric control groups in the experimental protocols. This study compared the effect of three experimental diets described in the literature – namely, a high-fat diet, a high-fat and high-sucrose diet, and a high-fat and high-fructose diet – to induce obesity in C57BL/6 J mice with the standard AIN-93G diet as a control. We hypothesize that the AIN diet formulation is not a good control in this type of experiment because this diet promotes weight gain and metabolic dysfunctions similar to the hypercaloric diet. The metabolic data of animals fed the AIN-93G diet were similar to those of the high-calorie groups (development of steatosis and hyperlipidemia). However, it is important to emphasize that the group fed a high-fat diet had a higher percentage of total fat (p = 0.0002) and abdominal fat (p = 0.013) compared to the other groups. Also, the high-fat group responded poorly to glucose and insulin tolerance tests, showing a picture of insulin resistance. As expected, the intake of the AIN-93G diet promotes metabolic alterations in the animals like the high-fat formulations. Therefore, although this diet continues to be used as the gold standard for growth and maintenance, it warrants a reassessment of its composition to minimize the metabolic changes observed in this study, thus updating its fitness as a normocaloric model of a standard rodent diet.</p></div>","PeriodicalId":72753,"journal":{"name":"Current research in physiology","volume":"5 ","pages":"Pages 436-444"},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ftp.ncbi.nlm.nih.gov/pub/pmc/oa_pdf/51/de/main.PMC9713253.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"35254877","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Regulation of collagen deposition in the trout heart during thermal acclimation","authors":"Elizabeth F. Johnston,&nbsp;Todd E. Gillis","doi":"10.1016/j.crphys.2022.02.004","DOIUrl":"10.1016/j.crphys.2022.02.004","url":null,"abstract":"<div><p>The passive mechanical properties of the vertebrate heart are controlled in part by the composition of the extracellular matrix (ECM). Changes in the ECM, caused by increased blood pressure, injury or disease can affect the capacity of the heart to fill with blood during diastole. In mammalian species, cardiac fibrosis caused by an increase in collagen in the ECM, leads to a loss of heart function and these changes in composition are considered to be permanent. Recent work has demonstrated that the cardiac ventricle of some fish species have the capacity to both increase and decrease collagen content in response to thermal acclimation. It is thought that these changes in collagen content help maintain ventricle function over seasonal changes in environmental temperatures. This current work reviews the cellular mechanisms responsible for regulating collagen deposition in the mammalian heart and proposes a cellular pathway by which a change in temperature can affect the collagen content of the fish ventricle through mechanotransduction. This work specifically focuses on the role of transforming growth factor β1, MAPK signaling pathways, and biomechanical stretch in regulating collagen content in the fish ventricle. It is hoped that this work increases the appreciation of the use of comparative models to gain insight into phenomenon with biomedical relevance.</p></div>","PeriodicalId":72753,"journal":{"name":"Current research in physiology","volume":"5 ","pages":"Pages 99-108"},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2665944122000116/pdfft?md5=ef7466eacb41bd15fdee92575b079a7f&pid=1-s2.0-S2665944122000116-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45097615","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reproductive effects of Abelmoschus esculentus fruit methanol extract in female Wistar rats","authors":"Eunice Ogunwole ,&nbsp;Jemimah Adoh Yakubu ,&nbsp;Vivian Tally Giwa","doi":"10.1016/j.crphys.2022.05.001","DOIUrl":"10.1016/j.crphys.2022.05.001","url":null,"abstract":"<div><p>Current researches aim at identifying modifiable risk factors for infertility, particularly dietary lifestyle. <em>Abelmoschus esculentus</em> is one of the important vegetables in the human diet with reported valuable nutrients but has been linked with reproductive dysfunction in males. This study investigated the reproductive effects of <em>Abelmoschus esculentus</em> fruit methanol extract in female Wistar rats. Dried <em>Abelmoschus esculentus</em> fruit was extracted with methanol. Fifteen female Wistar rats (180–200 g) grouped into three (n = 5) received 1.0 mL/kg/day distilled water (control), 70 and 200 mg/kg/day of the extract once daily for 21 days via oral gavage. The estrous cycle was assessed using Marcondes and Papanicolaou methods. The histology of the tissues was evaluated by microscopy. Serum follicle-stimulating hormone, luteinizing hormone, and estrogen levels were measured using an enzyme-linked immunosorbent assay. Tissue antioxidant activities and malondialdehyde levels were assayed by spectrophotometry. Data were analyzed using the Analysis of variance at a significance of p &lt; 0.05. The estrous cycle of the <em>Abelmoschus esculentus</em> fruit methanol extracts treated rats showed normal cellular characteristics. Though <em>Abelmoschus esculentus</em> fruit methanol extract increased the antioxidant activities, it reduced the body weight and follicle-stimulating hormone level and caused severe inflammation and fibrosis of the ovary and uterus. <em>Abelmoschus esculentus</em> fruit methanol extract adversely altered the reproductive functions of female Wistar rats by disrupting the ovarian and uterine cytology and reducing hormone levels.</p></div>","PeriodicalId":72753,"journal":{"name":"Current research in physiology","volume":"5 ","pages":"Pages 208-215"},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2665944122000207/pdfft?md5=d125c38e01b5a23f9c14324b05c4d8d4&pid=1-s2.0-S2665944122000207-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45149478","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Sustained hypoxia in mice increases parasympathetic but not sympathetic tone","authors":"Juliana R. Souza,&nbsp;Mauro de Oliveira,&nbsp;Benedito H. Machado","doi":"10.1016/j.crphys.2022.09.006","DOIUrl":"10.1016/j.crphys.2022.09.006","url":null,"abstract":"<div><p>The autonomic profile of mice submitted to sustained hypoxia (SH) was not yet fully evaluated. Herein, we characterized the cardiovascular and autonomic profile of conscious freely moving mice submitted to SH using two sequential experimental protocols to evaluate the parasympathetic and sympathetic tone to the heart and the sympathetic tone to the vascular resistance. In the first protocol the sequence of antagonists was methyl-atropine followed by propranolol and then by prazosin, while in the second protocol the sequence was propranolol followed by methyl-atropine and then by prazosin. In SH the baseline heart rate was significantly lower than in control mice and the antagonism of the parasympathetic and sympathetic tone to the heart in both experimental protocols indicated an increased parasympathetic tone in SH mice and no changes in the sympathetic tone. Antagonism of the sympathetic tone to the vascular resistance with prazosin produced similar changes in arterial pressure in control and SH mice. Altogether these findings support the concept that mice submitted to SH present a significant increase in the parasympathetic but not in the sympathetic tone, which may explain why the baseline arterial pressure was not increased in SH mice.</p></div>","PeriodicalId":72753,"journal":{"name":"Current research in physiology","volume":"5 ","pages":"Pages 361-368"},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ftp.ncbi.nlm.nih.gov/pub/pmc/oa_pdf/51/cd/main.PMC9516409.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"40389017","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Urine color expressed in CIE L*a*b* colorspace during rapid changes in hydration status","authors":"Tory Edwards,&nbsp;Michael J. Buono","doi":"10.1016/j.crphys.2022.06.007","DOIUrl":"10.1016/j.crphys.2022.06.007","url":null,"abstract":"<div><h3>Background</h3><p>To investigate how rapid changes in hydration affect urine color expressed in CIE L*a*b* colorspace.</p></div><div><h3>Methods</h3><p>This study was a two-day crossover design where subjects (N = 30) came in one visit dehydrated, after a 15 h overnight fluid deprivation, and rapidly rehydrated by drinking at least 1000 mL of water in 2 h. On the other visit subjects reported euhydrated and then rapidly dehydrated 2% by walking (3 mph) in a heat chamber (100°F, 50% humidity) for 2 h. Urine samples on both days were collected pre- and post-dehydration/rehydration. Urine osmolality, urine specific gravity, subjective urine color and objective urine color expressed in CIE L*a*b* colorspace were measured.</p></div><div><h3>Results</h3><p>In the dehydration trial participants experienced a significant weight loss of approximately 2% of their starting, euhydrated body weight. The CIE urine color L*-value significantly decreased (−2.3 units) while the b*-value significantly increased (16 units). Subjective urine color significantly increased (1 unit). Urine osmolality increased (25 mmol/kg) and urine specific gravity increased (0.002 g/mL) between the pre- and post-dehydration conditions, however, neither of these changes were statistically significant. In the rehydration trial participants had a significant 1.5% increase in body weight after the ingestion of water. Significant increases were observed in the CIE urine color L*-value (7 units) and a*-value (1.1 units), while the b*-value significantly decreased (−24 units). Subjective urine color significantly decreased (−3 units). Urine osmolality (−600 mmol/kg) and urine specific gravity (−0.018 g/mL) significantly decreased between the pre- and post-rehydration conditions.</p></div><div><h3>Conclusions</h3><p>Traditional markers of hydration, including urine osmolality and urine specific gravity, did not significantly change in the acute dehydration trial, suggesting that these values may not be responsive to rapid changes in hydration status. However, the CIE L*- and b*-values of urine color significantly decreased in the rapid dehydration trial and significantly increased in the rapid rehydration trial. Thus, the results of the current study suggest that urine color L*- and b*-values expressed in the CIE L*a*b* colorspace were more responsive to changes in hydration status during rapid dehydration than traditional indices of urine concentration and thus may be better markers under such conditions.</p></div>","PeriodicalId":72753,"journal":{"name":"Current research in physiology","volume":"5 ","pages":"Pages 251-255"},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ftp.ncbi.nlm.nih.gov/pub/pmc/oa_pdf/c3/fe/main.PMC9253385.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"40480545","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Regulation of cardiac ryanodine receptor function by the cyclic-GMP dependent protein kinase G","authors":"Luis A. Gonano ,&nbsp;Hamish M. Aitken-Buck ,&nbsp;Akash D. Chakraborty ,&nbsp;Luke P.I. Worthington ,&nbsp;Tanya R. Cully ,&nbsp;Regis R. Lamberts ,&nbsp;Martin G. Vila-Petroff ,&nbsp;Peter P. Jones","doi":"10.1016/j.crphys.2022.03.004","DOIUrl":"10.1016/j.crphys.2022.03.004","url":null,"abstract":"<div><h3>Background</h3><p>The cGMP-dependent protein kinase G (PKG) phosphorylates the cardiac ryanodine receptor (RyR2) <em>in vitro</em>. We aimed to determine whether modulation of endogenous PKG alters RyR2-mediated spontaneous Ca²⁺ release and whether this effect is linked to a change in RyR2 phosphorylation.</p></div><div><h3>Methods</h3><p>&amp; Results: Human embryonic kidney (HEK293) cells with inducible RyR2 expression were treated with the cGMP analogue 8-Br-cGMP (100 μM) to activate endogenous PKG. In cells transfected with luminal Ca²⁺ sensor, D1ER, PKG activation significantly reduced the threshold for RyR2-mediated spontaneous Ca²⁺ release (93.9 ± 0.4% of store size with vehicle vs. 91.7 ± 0.8% with 8-Br-cGMP, <em>P</em> = 0.04). Mutation of the proposed PKG phosphorylation sites, S2808 and S2030, either individually or as a combination, prevented the decrease in Ca²⁺ release threshold induced by endogenous PKG activation. Interestingly, despite a functional dependence on expression of RyR2 phosphorylation sites, 8-Br-cGMP activation of PKG did not promote a detectable change in S2808 phosphorylation (<em>P</em> = 0.9). Paradoxically, pharmacological inhibition of PKG with KT 5823 (1 μM) also reduced the threshold for spontaneous Ca²⁺ release through RyR2 without affecting S2808 phosphorylation. Silencing RNA knockdown of endogenous PKG expression also had no quantifiable effect on RyR2 S2808 phosphorylation (<em>P</em> = 0.9). However, unlike PKG inhibition with KT 5823, PKG knockdown did not alter spontaneous Ca²⁺ release propensity or luminal Ca²⁺ handling.</p></div><div><h3>Conclusion</h3><p>In an intact cell model, activation of endogenous PKG reduces the threshold for RyR2-mediated spontaneous Ca²⁺ release in a manner dependent on the RyR2 phosphorylation sites S2808 and S2030. This study clarifies the regulation of RyR2 Ca²⁺ release by endogenous PKG and functionally implicates the role of RyR2 phosphorylation.</p></div>","PeriodicalId":72753,"journal":{"name":"Current research in physiology","volume":"5 ","pages":"Pages 171-178"},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2665944122000165/pdfft?md5=0834dd5168204aa7c6caafe5dbd9ce07&pid=1-s2.0-S2665944122000165-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46707191","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The effects of voluntary wheel running during weight-loss on biomarkers of hepatic lipid metabolism and inflammation in C57Bl/6J mice","authors":"Joshua S. Wooten,&nbsp;Kaylee E. Poole,&nbsp;Matthew P. Harris,&nbsp;Brianne L. Guilford,&nbsp;Megan L. Schaller,&nbsp;David Umbaugh,&nbsp;Andrew Seija","doi":"10.1016/j.crphys.2022.01.003","DOIUrl":"10.1016/j.crphys.2022.01.003","url":null,"abstract":"<div><p>The aim of this study was to determine the effect of voluntary wheel running (VWR) during weight-loss on hepatic lipid and inflammatory biomarkers using a murine model. To induce obesity, male C57Bl/6 mice were fed a 60% high-fat diet (HF) for 10 weeks. At 10 weeks, weight-loss was promoted by randomizing HF-fed mice to a normal diet (ND) either with (WL + VWR) or without (WL) access to running wheels for 8 weeks. Age-matched dietary control mice were fed either a ND or HF for 18 weeks. Following weight-loss, WL + VWR had a lower body mass compared to all groups despite an average weekly caloric consumption comparable to HF mice. WL + VWR had an increased adiponectin concentration when compared to WL, but no difference between WL and WL + VWR was observed for plasma glucose and lipid biomarkers. When compared to HF, the lower hepatic total lipids in both WL and WL + VWR were associated with increased pAMPK:AMPK and reduced pACC-1:ACC-1 ratios. When compared to WL, WL + VWR resulted in lower hepatic cholesterol and trended to lower hepatic triglyceride. In both WL and WL + VWR, pNF-κB p65:NF-κB p65 ratio was lower than HF and comparable to ND. TGFβ1 and BAMBI protein levels were evaluated as biomarkers for hepatic fibrosis. No differences in TGFβ1 was observed between groups; however, WL and WL + VWR had BAMBI protein levels comparable to ND. Overall, the addition of voluntary exercise resulted in greater weight-loss and improvements in hepatic cholesterol and triglyceride levels; however, limited improvements in hepatic inflammation were observed when compared to weight-loss by diet alone.</p></div>","PeriodicalId":72753,"journal":{"name":"Current research in physiology","volume":"5 ","pages":"Pages 63-72"},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ftp.ncbi.nlm.nih.gov/pub/pmc/oa_pdf/fa/f7/main.PMC8814598.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39781502","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"White tea modulates antioxidant defense of endurance-trained rats","authors":"Patrícia Berilli ,&nbsp;Gustavo Bernardes Fanaro ,&nbsp;Jéssica Piva Santos ,&nbsp;Felix Guillermo Reyes Reyes ,&nbsp;Amadeu Hoshi Iglesias ,&nbsp;Marcella Reis ,&nbsp;Cínthia Baú Betim Cazarin ,&nbsp;Mário Roberto Maróstica Junior","doi":"10.1016/j.crphys.2022.06.002","DOIUrl":"10.1016/j.crphys.2022.06.002","url":null,"abstract":"<div><p>The interest in nutritional strategies that may counteract the deleterious oxidative effects induced by strenuous exercises is remarkable. Herein, the impact of white tea (<em>Camellia sinensis</em>) (WT), a polyphenol-rich beverage, on antioxidant status in endurance-trained rats after one session of exhaustive exercise were evaluated. Male Wistar rats were divided into groups, which received: control groups - water, and testing groups - WT1 (0.25%; w/v) or WT2 (0.5%; w/v). Drinks were consumed, <em>ad libitum</em>, for 5 or 10 weeks, concomitantly with the running training. Exhaustive running tests were applied before and after the experimental periods. WT intake increased the serum antioxidant capacity of rats in a dose-dependent manner (P &lt; 0.001), which was unaccompanied by the activity of endogenous antioxidant enzymes SOD, GPx, and GR, and GSH content. Inflammatory markers in serum [IL-1β (P = 0.004) and IL-6 (P = 0.001)] could be downregulated by tea intake. In liver tissue, lower levels of lipid oxidation (P &lt; 0.05) and improved antioxidant defenses (SOD, GPx, GR, and GSH, P &lt; 0.05) were related to the consumption of <span>WT</span> in both doses, supporting protective effects in this responsible metabolic organ. In conclusion, long-term consumption of WT could be a promising adjuvant to exercise-stress management, emphasizing its ability to regulate antioxidant responses and prevent oxidative tissue damage.</p></div>","PeriodicalId":72753,"journal":{"name":"Current research in physiology","volume":"5 ","pages":"Pages 256-264"},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ftp.ncbi.nlm.nih.gov/pub/pmc/oa_pdf/e6/12/main.PMC9253650.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"40491907","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Acute and chronic cold exposure differentially affect cardiac control, but not cardiorespiratory function, in resting Atlantic salmon (Salmo salar)","authors":"E.S. Porter,&nbsp;K.A. Clow,&nbsp;R.M. Sandrelli,&nbsp;A.K. Gamperl","doi":"10.1016/j.crphys.2022.03.002","DOIUrl":"10.1016/j.crphys.2022.03.002","url":null,"abstract":"<div><p>No studies have examined the effects of cold temperatures (∼0–1 °C) on <em>in vivo</em> cardiac function and control, and metabolism, in salmonids. Thus, we examined: 1) how acclimation to 8 °C vs. acclimation (&gt;3 weeks) or acute exposure (8-1 °C at 1 °C h⁻¹) to 1 °C influenced cardiorespiratory parameters in resting Atlantic salmon; and 2) if/how the control of cardiac function was affected. Oxygen consumption (<span><math><mover><mi>M</mi><mo>˙</mo></mover><msub><mi>O</mi><mn>2</mn></msub></math></span>) and cardiac function [i.e., heart rate (<em>f</em>_H) and cardiac output (<span><math><mrow><mover><mi>Q</mi><mo>˙</mo></mover><mo>)</mo></mrow></math></span>] were 50% lower in the acutely cooled and 1^oC-acclimated salmon as compared to 8 °C fish, whereas stroke volume (V_S) was unchanged. Intrinsic <em>f</em>_H was not affected by whether the fish were acutely exposed or acclimated to 1 °C (values ∼51, 24 and 21 beats min⁻¹ in 8 and 1 °C-acclimated fish, and 8-1 °C fish, respectively), and in all groups <em>f</em>_H was primarily under adrenergic control/tone (cholinergic tone 13–18%; adrenergic tone 37–70%). However, β-adrenergic blockade resulted in a 50% increase in V_S in the 1^oC-acclimated group, and this was surprising as circulating catecholamine levels were ∼1–3 nM in all groups. Overall, the data suggest that this species has a limited capacity to acclimate to temperatures approaching 0 °C. However, we cannot exclude the possibility that cardiac and metabolic responses are evoked when salmon are cooled to ∼ 0–1 °C, and that this prevented further declines in these parameters (i.e., they ‘reset’ quickly). Our data also provide further evidence that V_S is temperature insensitive, and strongly suggest that changes in adrenoreceptor mediated control of venous pressure/capacitance occur when salmon are acclimated to 1 °C.</p></div>","PeriodicalId":72753,"journal":{"name":"Current research in physiology","volume":"5 ","pages":"Pages 158-170"},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2665944122000141/pdfft?md5=c89a960d2d236c95b16ca54437076fea&pid=1-s2.0-S2665944122000141-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48286569","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The effective use of blebbistatin to study the action potential of cardiac pacemaker cells of zebrafish (Danio rerio) during incremental warming","authors":"Marchant James L. ,&nbsp;Smith Frank M. ,&nbsp;Farrell Anthony P.","doi":"10.1016/j.crphys.2022.01.002","DOIUrl":"https://doi.org/10.1016/j.crphys.2022.01.002","url":null,"abstract":"<div><p>Blebbistatin potently inhibits actin-myosin interaction, preventing contractile activity of excitable cells including cardiac myocytes, despite electrical excitation of an action potential (AP). We collected intracellular microelectrode recordings of pacemaker cells located in the sinoatrial region (SAR) of the zebrafish heart at room temperature and during acute warming to investigate whether or not blebbistatin inhibition of contraction significantly alters pacemaker cell electrophysiology. Changes were evaluated based on 16 variables that characterized the AP waveform. None of these AP variables nor the spontaneous heart rate were significantly modified with the application of 10 μM blebbistatin when recordings were made at room temperature. Compared with the control group, the blebbistatin-treated group showed minor changes in the rate of spontaneous diastolic depolarization (<em>P</em> = 0.027) and the 50% and 80% repolarization (<em>P</em> = 0.008 and 0.010, respectively) in the 26°C–29°C temperature bin, but not at higher temperatures. These findings suggest that blebbistatin is an effective excitation-contraction uncoupler that does not appreciably affect APs generated in pacemaking cells of the SAR and can, therefore, be used in zebrafish cardiac studies.</p></div>","PeriodicalId":72753,"journal":{"name":"Current research in physiology","volume":"5 ","pages":"Pages 48-54"},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2665944122000025/pdfft?md5=61b5f847b0ae51a68bb12f454eef3dad&pid=1-s2.0-S2665944122000025-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91635988","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}