Comparison of regional blood distribution in <i>Eptesicus fuscus</i> (big brown bat) during torpor (summer), hibernation (winter), and arousal

Rauch, Josefine C.; Beatty, David D.

doi:10.1139/z75-025

Cited by 19 publications

(6 citation statements)

References 7 publications

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“…Blood flow posterior to the diaphragm is restricted in arousing thirteen-lined ground squirrels until the thoracic temperature is ∼ 25° C (Bullard and Funkhouser, 1962). These data are consistent with data from the big brown bat where anterior organs receive greater fractions of cardiac output during early arousal (Rauch and Beatty, 1975). The restoration of blood flow to the periphery and skin may also have large effects on the level of heat loss to the environment.…”

Section: Discussionsupporting

confidence: 84%

Temporal and temperature effects on the maximum rate of rewarming from hibernation

Utz¹,

Velickovska²,

Shmereva³

et al. 2007

Journal of Thermal Biology

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During hibernation animals oscillate from near ambient (T a ) to euthermic body temperatures (T b ). As animals arouse, the rate of rewarming (RRW) might be expected to simply increase as a function of time. We monitored the T b of golden-mantled ground squirrels (Spermophilus lateralis) housed at 4, 8, 12, and 16° C during natural arousals. The maximum RRW, the time required to reach a maximum RRW, and the relative time index all demonstrated negative relationships with T a . The T b corresponding to maximal RRW demonstrated a positive relationship with T a . Squirrels reached maximal RRW when they had generated 30 to 40% of the heat required to reach a euthermic T b . These data suggest that arousal is more constrained than expected and that both time and temperature influence the RRW.

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Section: Discussionsupporting

confidence: 84%

Temporal and temperature effects on the maximum rate of rewarming from hibernation

Utz¹,

Velickovska²,

Shmereva³

et al. 2007

Journal of Thermal Biology

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“…Interestingly, the total glutathione pool decreased during torpor, but was replenished during interbout arousals, which supports the expected finding that reduced tissue perfusion increased oxidative damage. The conflicting results reported for these two species could conceivably reflect differences in tissue perfusion during hibernation (which have been well documented; [116,117]), with the heart and brain perhaps receiving more of the cardiac output during torpor and the gut experiencing a much more reduced blood flow regime.…”

Section: Mitochondrial Dysfunction and Generation Of Reactive Oxygen mentioning

confidence: 99%

Vertebrate cell death in energy-limited conditions and how to avoid it: what we might learn from mammalian hibernators and other stress-tolerant vertebrates

2010

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Dormancy in vertebrates may expose cells to acidosis, hypoxia/anoxia, oxidative damage, and extremes in temperature. All of these insults are known to be pro-apoptotic in typical vertebrate cells, especially mammals. Since dormancy is presumably the result of a need for energy conservation, the inherent energetic demand of replenishing cells that underwent apoptosis seems at odds with this strategy. This review will discuss processes to mitigate apoptosis and how these processes might be regulated in stress-tolerant vertebrates such as mammalian hibernators. As data directly addressing such issues are scarce and often conflicting, an apparently complex regulation of apoptosis seems to be at work. For example, apoptosis is mitigated during dormancy, key signaling events including the activation of caspase-3 may still occur. However, both passive, temperature-induced depression of apoptotic signaling as well as active suppression of apoptosis appear to work in synergy in these systems. In many instances cell death is prevented by simply avoiding the cellular triggers (e.g. leakage of proteins from the mitochondria or increases in intracellular calcium) that initiate apoptotic signaling. In this review we discuss what is known about programmed cell death in these under-studied models and highlight features of their physiology that likely support survival in the face of conditions that would induce cell death in typical vertebrate cells.

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“…Even though some nodal tissue was observed in the base of the posterior cusp of the right atrioventricular valve in Eptesicus, based upon insufficient data it is difficult to concur with the conclusions drawn by Walls and Anderson. However, it appears more than likely that Eptesicus, because of its rapid heart rate [800 beats/min in active flight, Rauch and Beatty, 1975], may need a far more sophisti cated system of valve closure than most other mammals to assure efficient cardiac function. James and Sherf [ 1968 a] consider the nodal cells ('P' or pacemaker cells) to be the cells responsible for the initiation of electrical im pulses in the conduction system.…”

Section: Location and Cellular Organization O F The Atrioventricular mentioning

confidence: 99%

“…This neural regulation of impulse formation may in some way ac count for the rapid change in the heart rate of Eptesicus [from 12 beats/min in hibernation to 800 beats/min in active flight within a period of 40 min. Rauch and Beatty, 1975].…”

Section: Innervation O F the Atrioventricular Nodementioning

confidence: 99%

Ultrastructure of the atrioventricular node of the big brown bat, <i>Eptesicus fucus</i>

Bhatnagar¹,

Spoonamore²

1979

Cells Tissues Organs

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This investigation describes the ultrastructure of the atrioventricular node of Eptesicusfuscus. Two conducting cell types (nodal and transitional) are identified which differ in location, myofibrillar content, and types of intercellular junctions. Centrally located nodal cells display variable staining intensity and contain disorganized myofibrils which rarely form sarcomeres. Desmosomes and nexus-like junctions connect the nodal cells. Transitional cells, situated peripherally, exhibit distinct sarcomeres and are attached to the adjacent cells through desmosomes and underdeveloped intercalated discs. Longitudinal arrangement of the mitochondrial cristae is frequently seen in both cell types. In the connective tissue stroma, numerous capillaries (with micropinocytotic vesicles), axons, and possibly axonal terminals, some filled with vesicles, are observed. A large ganglionated nerve trunk is present on the nodal periphery. True nexuses and neuromuscular junctions are not observed. It is suggested that nodal cell types previously reported in different vertebrates under various names are merely simple variations of the two basic types of conducting cells – nodal and transitional. No interspecffic differences are observed between these cells of the big brown bat compared with those in other vertebrates.

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Comparison of regional blood distribution in Eptesicus fuscus (big brown bat) during torpor (summer), hibernation (winter), and arousal

Cited by 19 publications

References 7 publications

Temporal and temperature effects on the maximum rate of rewarming from hibernation

Temporal and temperature effects on the maximum rate of rewarming from hibernation

Vertebrate cell death in energy-limited conditions and how to avoid it: what we might learn from mammalian hibernators and other stress-tolerant vertebrates

Ultrastructure of the atrioventricular node of the big brown bat, <i>Eptesicus fucus</i>

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