Myocardial metabolic and electrical properties of rabbits and ground squirrels at low temperatures

1959 ◽  
Vol 197 (2) ◽  
pp. 494-498 ◽  
Author(s):  
Benjamin G. Covino ◽  
John P. Hannon
Keyword(s):  
Low Temperatures ◽  
Ground Squirrel ◽  
Coronary Flow ◽  
Rabbit Heart ◽  
Ground Squirrels ◽  
The Body ◽  
Perfusion Fluid ◽  
Flow Rates ◽  
Ventricular Tissue

When perfused in vitro with Krebs-Henseleit solution both rabbit and arctic squirrel hearts exhibit similar contraction rates in a temperature range of 35°–25°C. Below 25° the rabbit heart was more susceptible to the present effect of cold. A reduction in temperature produced a much more pronounced depression in diastolic ventricular excitability in the rabbit than in the ground squirrel. At any given temperature, both species had quite similar in vitro coronary flow rates. As the perfusion fluid was cooled, however, flow rates of both species were markedly lowered. Ventricular tissue removed from rabbits with rectal temperatures of 15°C showed that a conversion of ATP to ADP had occurred. Lowering of the body temperature to 15°C in squirrels had no effect on ventricular ATP levels. At both normal and hypothermic temperatures, the total ventricular nucleotide content was much higher in squirrels than in rabbits. At 38° and at 15° squirrels exhibited a higher glutamic but a lower ß-hydroxybutyric, malic and succinic oxidase activity than rabbits.

Temperature dependence of in vitro androgen production in testes from hibernating ground squirrels, Spermophilus lateralis

1987 ◽  
Vol 65 (12) ◽  
pp. 3020-3023 ◽  
Author(s):  
Brian M. Barnes ◽  
Paul Licht ◽  
Irving Zucker
Keyword(s):  
Ground Squirrel ◽  
Temperature Compensation ◽  
Laboratory Mouse ◽  
Ground Squirrels ◽  
The Body ◽  
Effect Of Temperature ◽  
Dependent Manner ◽  
Spermophilus Lateralis ◽  
Dose Dependent

The effect of temperature on the in vitro androgen secretion of testes from hibernating ground squirrels was measured in response to stimulation by luteinizing hormone (LH). We wished to determine whether hibernating ground squirrels can maintain responsiveness of gonads while at the low body temperatures of torpor. In gonads incubated at 32 °C, secretion of testosterone increased in a dose-dependent manner in response to ovine-LH or ground squirrel pituitary homogenate. This responsiveness was reduced at 20 and 9 °C and absent at 5 °C, the temperature that most closely approximates the body temperature of torpid ground squirrels. This temperature sensitivity was similar to that in the nonhibernating laboratory mouse. Superfusion of ground squirrel testes revealed a lag of testosterone secretion in response to LH and, additionally, an ability of testes to secrete testosterone after being only briefly exposed to ovine-LH while at 5 °C. These results provide evidence against a hypothesis of temperature compensation that would allow continued testis function during torpor, and support a previous study which indicated that gonadal growth is restricted to intervals of normothermy during and after the hibernation season.

scholarly journals Resistance of Erythrocytes of Hibernating Mammals to Loss of Potassium during Hibernation and during Cold Storage

1971 ◽  
Vol 58 (6) ◽  
pp. 620-633 ◽  
Author(s):  
S. L. Kimzey ◽  
J. S. Willis
Keyword(s):  
Ground Squirrel ◽  
Normal Values ◽  
Ground Squirrels ◽  
Storage Medium ◽  
Cold Adapted ◽  
Maximum Period ◽  
K Concentration

In two species of hibernators, hamsters and ground squirrels, erythrocytes were collected by heart puncture and the K content of the cells of hibernating individuals was compared with that of awake individuals. The K concentration of hamsters did not decline significantly during each bout of hibernation (maximum period of 5 days) but in long-term bouts in ground squirrels (i.e. more than 5 days) the K concentration of cells dropped significantly. When ground squirrels were allowed to rewarm the K content of cells rose toward normal values within a few hours. Erythrocytes of both hamsters and ground squirrels lose K more slowly than those of guinea pigs (nonhibernators) when stored in vitro for up to 10 days at 5°C. In ground squirrels the rate of loss of K during storage is the same as in vivo during hibernation, and stored cells taken from hibernating ground squirrels also lose K at the same rate. The rate of loss of K from guinea pig cells corresponded with that predicted from passive diffusion unopposed by transport. The actual rate of loss of K from ground squirrel cells was slower than such a predicted rate but corresponded with it when glucose was omitted from the storage medium or ouabain was added to it. Despite the slight loss of K that may occur in hibernation, therefore, the cells of hibernators are more cold adapted than those of a nonhibernating mammal, and this adaptation depends in part upon active transport.

Temperature sensitivity of renin-angiotensin system in the ground squirrel

1987 ◽  
Vol 253 (3) ◽  
pp. F471-F475
Author(s):  
C. T. Harker ◽  
M. J. Kluger ◽  
R. L. Malvin
Keyword(s):  
Ground Squirrel ◽  
Renin Angiotensin System ◽  
Ground Squirrels ◽  
Renin Release ◽  
Temperature Sensitive ◽  
Beta Adrenoceptors ◽  
Beta Agonists ◽  
Alpha Agonist

The alteration of renin release by alpha- and beta-adrenoceptors located on the juxtaglomerular cells has been shown to be temperature sensitive in nonhibernating mammals. These experiments investigate the effects of temperature on renin secretion by cortical slices of kidneys from the thirteen-lined ground squirrel Spermophilus tridecemlineatus. At 37 degrees C, beta-stimulation (isoproterenol 10(-7) M) increased the release of renin by slices taken from nonhibernating ground squirrels but had no effect on those taken from hibernating squirrels. The alpha-agonist phenylephrine (10(-5) M) had no effect on slices from nonhibernating squirrels but enhanced the release rate in those from hibernating ground squirrels, providing the first evidence of in vitro stimulation of renin release by an alpha-agonist. When incubated at 11 degrees C, kidney slices from both hibernating and nonhibernating animals were unresponsive to both alpha- and beta-agonists until incubation times were doubled. Under these prolonged conditions, phenylephrine again stimulated renin release. These results indicate that both in vitro and in vivo cooling alter the responses of alpha- and beta-adrenoceptors to renin-releasing stimuli.

scholarly journals Vascularization of the kidney of the ground squirrel (Citellus citellus) in comparison with other experimental animals

2015 ◽  
Vol 69 (1-2) ◽  
pp. 31-40
Author(s):  
Milos Blagojevic ◽  
Dusko Vitorovic ◽  
Ivana Adamovic ◽  
Ivana Nesic ◽  
Zlata Brkic ◽  
...  
Keyword(s):  
Renal Artery ◽  
Blood Vessels ◽  
Abdominal Aorta ◽  
Ground Squirrel ◽  
Comparative Anatomy ◽  
Lateral Wall ◽  
Ground Squirrels ◽  
The Body ◽  
Hot Water ◽  
The Right

Ground squirrel is the only representative of its genus in our country. As experimental animal is used in microbiology, parasitology, immunology and pharmacology. The aim of this study was to examine a part of ground squirrel cardiovascular system and thus help better understanding of anatomy of the body of this specific animal as well as to contribute to comparative anatomy. The studies were perfomed on six ground squirrels, both sexes, weight between 200- 300 g. In order to obtain the arterial vascularization of the kidney, contrast mass gelatin stained with painting tempera was injected into the abdominal aorta after bleeding out. After the injection, blood vessels were prepared and photographed. Corosive preparations of the vein blood vessels of the kidneys were obtained by injection of Byocril into the right azygos vein after bleeding out. After injection, the preparations were placed into 5% NaOH for 96 hours or 10% NaOH for 48 hours. After that the preparations were rinsed with hot water and photographed. A. renalis dextra arises from the lateral wall of the abdominal aorta, 3-4 mm caudal to A. mesenterica cranialis. In most cases, this vessel divides into two or three branches before entering the hilus of the right kidney. A. renalis sinistra arises from the lateral wall of the abdominal aorta, 7-9 mm caudal to the right renal artery. Often, instead of one left renal artery, there are two, rarely three. Based on the results of our study, we concluded that in ground squirrel there is one A. renalis dextra and often two, rarely three Aa. renales sinistrae. In renal venous vascularization, both right and left renal vein are involved. Before entering the kidney, both of them divide into cranial and caudal branch, undergoing renal hilus, enter the renal sinus and continues to branch out into smaller branches.

scholarly journals A. facialis in ground squirrel (Citellus itellus)

2016 ◽  
Vol 70 (5-6) ◽  
pp. 205-214
Author(s):  
Milos Blagojevic ◽  
Zora Nikolic ◽  
Ivana Bozickovic ◽  
Marija Zdravkovic
Keyword(s):  
Head And Neck ◽  
Blood Vessels ◽  
Thoracic Aorta ◽  
Ground Squirrel ◽  
Comparative Anatomy ◽  
Ground Squirrels ◽  
The Body ◽  
Hot Water ◽  
Arterial Blood ◽  
Organ Systems

A ground squirrel is a hibernator, which hibernation lasts, depending on the age and sex, since the end of the summer until the spring. During this period in the body of ground squirrel, as well as in other hibernators, starts lowering of all vital functions, what has been proven by numerous physiological, biochemical and histological examinations of some organ systems of this animal. The objective of our work was to investigate a part of cardiovascular system of ground squirrel so in that way to contribute to a better knowledge of this animal body structure and accordingly to comparative anatomy in general. The investigation included 6 ground squirrels, of both gender, body weight 200-300 grams. For obtaining head and neck arterial vascularization, after exsanguination of the animal, contrast mass of gelatin coloured with tempera was injected into thoracic aorta (Aorta thoracica). After injecting, the blood vessels were prepared and photographed. For obtaining the corrosive preparations of head and neck arterial blood vessels, after exsanguination of the animal, Biocryl (a mixture of liquid biocryl - methil - methacrylate monomer and biocryl in powder - methil - methacrylate polymer) was injected into thoracic aorta (Aorta thoracica). After injecting the preparations were placed into 5% NaOH, for 96 hours or into 10% NaOH for 48 hours. After that they were rinsed in hot water and photographed. A. facialis in ground squirrel is an extension of A. maxillaris. The branches of A. facialis are: A. labialis inferior, A. bursae buccalis dorsalis, A. labialis superior, A. dorsalis nasi and A. angularis oculi. The obtained results regarding A. facialis in ground squirrel (Citellus citellus) were compared to the same ones in rats. In rats, A. facialis is the biggest branch separating from A. carotis externa. The branches of A. facialis in rats are: Ramus glandularis, A. submentalis, A. masseterica ventralis, A. labialis inferior, A. angularis oris, A. labialis superior, Rami musculares, A. lateralis nasi and A. angularis oculi. Based on the above mentioned results, it can be concluded that both in ground squirrel and rat A. facialis branches into A. labialis inferior, A. labialis superior and A. angularis oculi. In ground squirrel the branches of A. facialis are also A. bursae buccalis dorsalis and A. dorsalis nasi, and in rat those are Ramus glandularis, A. submentalis, A. masseterica ventralis, A. angularis oris, Rami musculares and A. lateralis nasi.

scholarly journals Neuronal UCP1 expression suggests a mechanism for local thermogenesis during hibernation

2015 ◽  
Vol 112 (5) ◽  
pp. 1607-1612 ◽  
Author(s):  
Willem J. Laursen ◽  
Marco Mastrotto ◽  
Dominik Pesta ◽  
Owen H. Funk ◽  
Jena B. Goodman ◽  
...  
Keyword(s):  
Body Temperature ◽  
Molecular Mechanisms ◽  
Brain Temperature ◽  
Uncoupling Protein ◽  
Ground Squirrels ◽  
The Body ◽  
Mitochondrial Uncoupling ◽  
Mitochondrial Uncoupling Protein ◽  
Brown Adipose

Hibernating mammals possess a unique ability to reduce their body temperature to ambient levels, which can be as low as −2.9 °C, by active down-regulation of metabolism. Despite such a depressed physiologic phenotype, hibernators still maintain activity in their nervous systems, as evidenced by their continued sensitivity to auditory, tactile, and thermal stimulation. The molecular mechanisms that underlie this adaptation remain unknown. We report, using differential transcriptomics alongside immunohistologic and biochemical analyses, that neurons from thirteen-lined ground squirrels (Ictidomys tridecemlineatus) express mitochondrial uncoupling protein 1 (UCP1). The expression changes seasonally, with higher expression during hibernation compared with the summer active state. Functional and pharmacologic analyses show that squirrel UCP1 acts as the typical thermogenic protein in vitro. Accordingly, we found that mitochondria isolated from torpid squirrel brain show a high level of palmitate-induced uncoupling. Furthermore, torpid squirrels during the hibernation season keep their brain temperature significantly elevated above ambient temperature and that of the rest of the body, including brown adipose tissue. Together, our findings suggest that UCP1 contributes to local thermogenesis in the squirrel brain, and thus supports nervous tissue function at low body temperature during hibernation.

Maintenance of ion concentration gradients in the cold in aorta from rat and ground squirrel

1979 ◽  
Vol 237 (1) ◽  
pp. C17-C22 ◽  
Author(s):  
K. E. Kamm ◽  
M. L. Zatzman ◽  
A. W. Jones ◽  
F. E. South
Keyword(s):  
Smooth Muscle ◽  
Low Temperatures ◽  
Ground Squirrel ◽  
Prolonged Exposure ◽  
Divalent Cations ◽  
Ground Squirrels ◽  
Ion Concentration ◽  
Cell Water ◽  
Concentration Gradients ◽  
Aortic Smooth Muscle

Cell water and ionic content were measured in aortic smooth muscle from rats and ground squirrels during 48 h of incubation in oxygenated Krebs solution held at low temperatures. Cells from the ground squirrel, a hibernator, maintained sodium and potassium contents near normal levels during incubation at 7 degrees C. In sharp contrast, cells from the rat lost potassium and gained sodium with half times of 14 and 11 h, respectively. The [K] in cell water for the rat decreased 138 mM while [Na] in cell water increased about 148 mM. Cells from the hibernator tended to lose 10 mM K and gain 13 mM Na. Vascular smooth muscle of both the rat and squirrel was able to maintain K content at 17 degrees C. Tissue content of the divalent cations Ca and Mg did not change in vessels from either animal. The present findings suggest that aortic smooth muscle cells from a hibernator have adapted in such a way as to maintain ionic gradients upon prolonged exposure to low temperatures.

The Role of Polyphenols in the Modulation of Plasma Non-Enzymatic Antioxidant Capacity (NEAC)

2012 ◽  
Vol 82 (3) ◽  
pp. 228-232 ◽  
Author(s):  
Mauro Serafini ◽  
Giuseppa Morabito
Keyword(s):  
Antioxidant Capacity ◽  
Dietary Intervention ◽  
Ex Vivo ◽  
The Body ◽  
Dietary Polyphenols ◽  
Enzymatic Antioxidant ◽  
Endogenous Antioxidant

Dietary polyphenols have been shown to scavenge free radicals, modulating cellular redox transcription factors in different in vitro and ex vivo models. Dietary intervention studies have shown that consumption of plant foods modulates plasma Non-Enzymatic Antioxidant Capacity (NEAC), a biomarker of the endogenous antioxidant network, in human subjects. However, the identification of the molecules responsible for this effect are yet to be obtained and evidences of an antioxidant in vivo action of polyphenols are conflicting. There is a clear discrepancy between polyphenols (PP) concentration in body fluids and the extent of increase of plasma NEAC. The low degree of absorption and the extensive metabolism of PP within the body have raised questions about their contribution to the endogenous antioxidant network. This work will discuss the role of polyphenols from galenic preparation, food extracts, and selected dietary sources as modulators of plasma NEAC in humans.

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