Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology 
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This is an RSS file. You can use it to subscribe to this data in your favourite RSS reader or to display this data on your own website or blog.Cardiorespiratory patterns of male South American sea lions (Otaria flavescens) resting on land
AbstractThe goal of this study was to characterize the cardiorespiratory patterns of male South American sea lions (SASLs,Otaria flavescens) resting on land. We recorded respiratory and heart rate (n = 360 individuals studied) by observing the nostrils, chest movements and the impact of the heart on the thoracic wall. The sea lions breathe apneustically with a pause on inspiration, representing 74% of the respiratory cycle. The mean breathing frequency was 3.2 ± 1.0 breaths min−1, with a breathing cycle presenting periods of bradypneas, tachypneas, and long-term post-inspiratory pauses. The normal heart rate ...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - February 1, 2024 Category: Physiology Source Type: research
Hypoxic and hypercapnic burrow conditions lead to downregulation of free triiodothyronine and hematocrit in Ansell ’s mole-rats (Fukomys anselli)
AbstractAfrican mole-rats live in self-dug burrow systems under hypoxic and hypercapnic conditions. Adaptations to hypoxia include suppression of resting metabolic rate (RMR) and core body temperature (Tb). Because the thyroid hormones (THs) thyroxine (T4) and triiodothyronine (T3) are positive regulators of RMR andTb, we hypothesized that serum TH concentrations would also be downregulated under hypoxic conditions. To test this hypothesis, we kept Ansell ’s mole-rats (Fukomys anselli) in terraria filled with soil in which they were allowed to construct underground burrows to achieve chronic intermittent hypoxia and hype...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - February 1, 2024 Category: Physiology Source Type: research
Activation of oxytocinergic neurons enhances torpor in mice
We report that activation of oxytocin neurons alone is not sufficient to induce a torpor-like state in the fed mouse, with no significant difference in body temperature or heart rate upon activation of oxytocin neurons. However, we found that activation of oxytocin neurons prior to the onset of daily torpor both deepens and lengthens the subsequent bout, with a 1.7 ± 0.4 °C lower body temperature and a 135 ± 32 min increase in length. We therefore conclude that oxytocin neurons are involved in the neural circuitry controlling daily torpor in the mouse. (Source: Journal of Comparative Physiology B: Biochemical...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - February 1, 2024 Category: Physiology Source Type: research
On the significance of aspartate aminotransferase and creatine kinase in wild reptile health studies
AbstractIn reptile medicine, the enzymes aspartate aminotransferase (AST) and creatine kinase (CK) have been used in clinical diagnostics, where CK is considered an enzyme specific to muscle cell damage, while AST is a nonspecific enzyme that is mainly produced in the liver and muscle. When many native reptiles are sampled, it is evident that there are important differences between species and individuals belonging to the same species, making the AST and CK ranges very wide. The minimum and maximum values, variations and standard deviations were extracted for each enzyme from 17 wild reptile studies, revealing high variati...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - February 1, 2024 Category: Physiology Source Type: research
Electron transport system supercomplexes affect reactive-oxygen species production and respiration in both a hibernator (Ictidomys tridecemlineatus) and a nonhibernator (Rattus norvegicus)
In this study, we investigate the relationship between supercomplex abundance and performance of liver mitochondria isolated from rats that do not hibernate and hibernating ground squirrels in which metabolism fluctuates substantially. We quantified the abundance of SCs (respirasomes (SCs containing CI, CIII, and CIV) or SCs containing CIII and CIV) and examined the relationship with state 3 (OXPHOS) and state 4 (LEAK) respiration rate, as well as net ROS production. We found that, in rats, state 3 and 4 respiration rate correlated negatively with respirasome abundance, but positively with CIII/CIV SC abundance. Despite th...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - February 1, 2024 Category: Physiology Source Type: research
Pre-hibernation diet alters skeletal muscle relaxation kinetics, but not force development in torpid arctic ground squirrels
AbstractDuring the hibernation season, Arctic ground squirrels (AGS) experience extreme temperature fluctuations (body temperature,Tb, as low as − 3 °C), during which they are mostly physically inactive. OnceTb reaches ~ 15 °C during interbout arousals, hibernators recruit skeletal muscle (SkM) for shivering thermogenesis to reachTb of ~ 35 °C. Polyunsaturated fatty acids (PUFA) in the diet are known to influence SkM function and metabolism. Recent studies in the cardiac muscle of hibernators have revealed that increased levels of ω-6 and the ω-6:ω-3 PUFA ratio correlate with sarco/endoplasmic reticulum ...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - February 1, 2024 Category: Physiology Source Type: research
Involvement of sodium –glucose cotransporter-1 activities in maintaining oscillatory Cl− currents from mouse submandibular acinar cells
AbstractIn salivary acinar cells, cholinergic stimulation induces elevations of cytosolic [Ca2+]i to activate the apical exit of Cl− through TMEM16A Cl− channels, which acts as a driving force for fluid secretion. To sustain the Cl− secretion, [Cl−]i must be maintained to levels that are greater than the electrochemical equilibrium mainly by Na+-K+-2Cl− cotransporter-mediated Cl− entry in basolateral membrane. Glucose transporters carry glucose into the cytoplasm, enabling the cells to produce ATP to maintain Cl− and fluid secretion. Sodium –glucose cotransporter-1 is a glucose transporter highly expressed ...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - February 1, 2024 Category: Physiology Source Type: research
Functional interactions between coat structure and colour in the determination of solar heat load on arid living kangaroos in summer: balancing crypsis and thermoregulation
AbstractInteractions of solar radiation with mammal fur are complex. Reflection of radiation in the visible spectrum provides colour that has various roles, including sexual display and crypsis, i.e., camouflage. Radiation that is absorbed by a fur coat is converted to heat, a proportion of which impacts on the skin. Not all absorption occurs at the coat surface, and some radiation penetrates the coat before being absorbed, particularly in lighter coats. In studies on this phenomenon in kangaroos, we found that two arid zone species with the thinnest coats had similar effective heat load, despite markedly different solar r...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - February 1, 2024 Category: Physiology Source Type: research
Expression patterns of heat-shock genes during stopover and the trade-off between refueling and stress response in a passerine migrant
We examined the gene expression patterns of different Heat Shock Proteins (HSPs) in migrating birds during stopover at different body condition states (lean vs. fat), to provide some first insights on the role of HSPs in bird migration and explore the concept of a trade-off between refueling and stress response. Our results showed upregulation of HSP expression at release that could be associated with muscle growth and increased cholesterol and lipid synthesis needed for birds to fuel their upcoming migration. On the other hand, during capture, upregulation of HSP5 could be attributed to physiological recovery from the non...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - February 1, 2024 Category: Physiology Source Type: research
Mechanism of post-tetanic depression of slow muscle fibres
AbstractA brief tetanic stimulation has a very different effect on the subsequent isometric twitch force of fast and slow skeletal muscles. Fast muscle responds with an enhanced twitch force which doubles that of the pre-tetanic value, whereas slow muscle depresses the post-tetanic twitch by about 20%. Twitch potentiation of fast muscle has long been known to be due to myosin light chain 2 phosphorylation. It is proposed that post-tetanic twitch depression in slow muscle is due to the dephosphorylation of the slow isoform of the thick filament protein, myosin-binding protein-C, by Ca2+/calmodulin-activated phosphatase calc...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - February 1, 2024 Category: Physiology Source Type: research
Expression patterns of heat-shock genes during stopover and the trade-off between refueling and stress response in a passerine migrant
We examined the gene expression patterns of different Heat Shock Proteins (HSPs) in migrating birds during stopover at different body condition states (lean vs. fat), to provide some first insights on the role of HSPs in bird migration and explore the concept of a trade-off between refueling and stress response. Our results showed upregulation of HSP expression at release that could be associated with muscle growth and increased cholesterol and lipid synthesis needed for birds to fuel their upcoming migration. On the other hand, during capture, upregulation of HSP5 could be attributed to physiological recovery from the non...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - January 31, 2024 Category: Physiology Source Type: research
Pre-hibernation diet alters skeletal muscle relaxation kinetics, but not force development in torpid arctic ground squirrels
AbstractDuring the hibernation season, Arctic ground squirrels (AGS) experience extreme temperature fluctuations (body temperature,Tb, as low as − 3 °C), during which they are mostly physically inactive. OnceTb reaches ~ 15 °C during interbout arousals, hibernators recruit skeletal muscle (SkM) for shivering thermogenesis to reachTb of ~ 35 °C. Polyunsaturated fatty acids (PUFA) in the diet are known to influence SkM function and metabolism. Recent studies in the cardiac muscle of hibernators have revealed that increased levels of ω-6 and the ω-6:ω-3 PUFA ratio correlate with sarco/endoplasmic reticulum ...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - January 14, 2024 Category: Physiology Source Type: research
Activation of oxytocinergic neurons enhances torpor in mice
We report that activation of oxytocin neurons alone is not sufficient to induce a torpor-like state in the fed mouse, with no significant difference in body temperature or heart rate upon activation of oxytocin neurons. However, we found that activation of oxytocin neurons prior to the onset of daily torpor both deepens and lengthens the subsequent bout, with a 1.7 ± 0.4 °C lower body temperature and a 135 ± 32 min increase in length. We therefore conclude that oxytocin neurons are involved in the neural circuitry controlling daily torpor in the mouse. (Source: Journal of Comparative Physiology B: Biochemical...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - January 3, 2024 Category: Physiology Source Type: research
Hypoxic and hypercapnic burrow conditions lead to downregulation of free triiodothyronine and hematocrit in Ansell ’s mole-rats (Fukomys anselli)
AbstractAfrican mole-rats live in self-dug burrow systems under hypoxic and hypercapnic conditions. Adaptations to hypoxia include suppression of resting metabolic rate (RMR) and core body temperature (Tb). Because the thyroid hormones (THs) thyroxine (T4) and triiodothyronine (T3) are positive regulators of RMR andTb, we hypothesized that serum TH concentrations would also be downregulated under hypoxic conditions. To test this hypothesis, we kept Ansell ’s mole-rats (Fukomys anselli) in terraria filled with soil in which they were allowed to construct underground burrows to achieve chronic intermittent hypoxia and hype...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - December 7, 2023 Category: Physiology Source Type: research
Effect of hypoxia duration and pattern on channel Catfish (Ictalurus punctatus) neuropeptide gene expression and hematology
This study did not find a significant change in hypothalamic transcription of CRF and UI during hypoxia challenges but did identify multiple physiological adaptive resp onses that work together to reduce the severity of experimentally induced hypoxia in channel catfish. (Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology)
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - December 1, 2023 Category: Physiology Source Type: research
