Bone mechanical properties after exercise training in young and old rats

1990 ◽  
Vol 68 (1) ◽  
pp. 130-134 ◽  
Author(s):  
D. M. Raab ◽  
E. L. Smith ◽  
T. D. Crenshaw ◽  
D. P. Thomas
Keyword(s):  
Mechanical Properties ◽  
Dry Weight ◽  
Ultimate Stress ◽  
Moment Of Inertia ◽  
Female Rats ◽  
Stress And Strain ◽  
Nonsignificant Trend ◽  
Fischer 344 ◽  
Old Rats ◽  
Both Bones

The effects of a 10-wk training regimen on the mechanical properties of the femur and humerus were evaluated in 2.5- and 25-mo-old Fischer 344 female rats. The rats trained on a rodent treadmill 5 days/wk for 10 wk. Duration, grade, and speed increased until the rats maintained 1 h/day at 15% grade and either 15 m/min (old rats) or 36 m/min (young rats). Excised bones were mechanically tested with a 3-point flexure test for mechanical properties of force, stress, and strain. Fat-free dry weight (FFW) and moment of inertia were also obtained. With aging, similar increases were observed in both the femur and humerus for FFW, moment of inertia, and force. Ultimate stress was reduced in the senescent femur while strain was elevated; a similar but nonsignificant trend was observed in the humerus. Irrespective of age, training increased FFW in the femur and, to a lesser degree, in the humerus. Breaking force was elevated for both bones after training. In young and old bones, the training-induced differences in bone mass and force were similar, despite differences in training intensity. In the old trained rats, femur ultimate stress was greater than that in control rat femurs and similar to that in young rat femurs. The results of the present study indicate that training effects were not limited by age.

scholarly journals The effect of calcium intake on bone composition and bone resorption in the young growing rat

2001 ◽  
Vol 86 (4) ◽  
pp. 453-459 ◽  
Author(s):  
Annette Creedon ◽  
Kevin D. Cashman
Keyword(s):  
Bone Resorption ◽  
Bone Mineral ◽  
Dry Weight ◽  
Female Rats ◽  
Wistar Strain ◽  
Restricted Group ◽  
Growing Rat ◽  
Old Rats ◽  
Bone Mineral Accrual ◽  
Recommended Level

A low Ca intake by both rats and man increases bone resorption, decreases bone mass and increases the risk of osteoporosis. The skeletal effect of high Ca intakes is less clear, particularly during periods of bone mineral accrual. Twenty-four female 5-week-old rats, Wistar strain, were randomized by weight into three groups of eight rats each and fedad libituma semi-purified diet containing 2 (Ca-restricted), 5 (normal) or 20 (Ca-supplemented) g Ca/kg for 3 weeks. When compared with the normal Ca diet, urinary Ca excretion was unaffected by the dietary restriction of Ca for 3 weeks, but was greater (P<0·001) in Ca-supplemented rats. Urinary pyridinoline (Pyr) and deoxypyridinoline (Dpyr) levels were significantly greater during weeks 2 (PyrP<0·05, DpyrP<0·001) and 3 (PyrP<0·01, Dpyr,P<0·001) of dietary Ca restriction, but were unaffected by Ca supplementation. Femoral dry weight and the concentration of Mg and P in femora were unaffected by dietary Ca concentration. Femoral Ca concentration was reduced (P<0·05) in the Ca-restricted group compared with the other two groups. In conclusion, these results suggest that increasing dietary Ca intake, well above the recommended level, had no effect on bone mineral composition or bone resorption (as assessed with urinary pyridinium crosslinks) in young growing female rats. In addition, these results confirm the findings of previous studies which have shown that bone Ca content in young growing rats was reduced by dietary Ca restriction and that this reduction results, at least in part, from an increased rate of bone resorption.

On the effect of vacancy defect on the mechanical properties of gallium nitride nanosheets

2016 ◽  
Vol 30 (22) ◽  
pp. 1650151 ◽  
Author(s):  
Saeed Rouhi
Keyword(s):  
Mechanical Properties ◽  
Gallium Nitride ◽  
Tensile Loading ◽  
Md Simulations ◽  
Tensile Tests ◽  
Vacancy Defect ◽  
Ultimate Stress ◽  
Stress And Strain ◽  
Vacancy Defects ◽  
Fracture Evolution

Using molecular dynamics (MD) simulations, the influence of the vacancy defects on the mechanical properties of gallium nitride (GaN) nanosheets is investigated. Two types of defective nanosheets are studied. In one of them, only one atom is removed at the vacancies and in the other, the number of removed atoms is not limited. It is shown that GaN nanosheets with multiple vacancies have larger in-plane elastic modulus than nanosheets with single vacancies. Besides, the ultimate stress and strain of GaN nanosheets are computed. Compared to perfect nanosheet, a significant decrease is observed in the ultimate stress of GaN nanosheet with only 2% defect. By plotting the fracture evolution of nanosheets under uni-directional tensile loading, three different patterns are observed. Moreover, by using bi-directional tensile tests on the nanosheets, the bulk moduli of perfect and defective GaN nanosheets are computed.

LH responses to LHRH, DBcAMP, and 17 beta-estradiol in cultures derived from aged rats

1981 ◽  
Vol 240 (5) ◽  
pp. E510-E518
Author(s):  
L. K. Tang ◽  
F. Y. Tang
Keyword(s):  
Luteinizing Hormone ◽  
Control Level ◽  
Female Rats ◽  
Female Rat ◽  
Aged Rats ◽  
Luteinizing Hormone Releasing Hormone ◽  
Cyclic Monophosphate ◽  
Fischer 344 ◽  
Lh Release ◽  
Old Rats

Effects of luteinizing hormone-releasing hormone (LHRH), N6,O2'-dibutyryl adenosine 3',5'-cyclic monophosphate (DBcAmP), and 17 beta-estradiol (E2) on LH responses were compared in 4-day-old pituitary cultures derived from female rats (Fischer 344) of 9 and 31 mo of age. Pituitary LH contents were similar in 5 X 10(5) freshly dispersed cells prepared from the two groups of rats. LH release in response to a 4-h incubation with 10 nM LHRH was virtually the same in cultures derived from 9- and 31-mo-old rats, 140 +/- 2 ng and 138 +/- 18 ng/4 h, respectively. In cultures derived from 9-mo-old rats, incubation with 8 mM DBcAMP for 4 h significantly stimulated LH release (286% of control level), and treatment with 10 nM E2 for 3 days significantly increased both basal LH release and LH accumulation (sum of LH contents in cells and medium) to 162 and 125% of control level, respectively. Neither DBcAMP nor E2 affected cultures derived from the 31-mo-old rats. These results indicate that there is a difference in the LH response to DBcAMP and E2 between cultures derived from 9- and 31-mo-old rats. The loss of pituitary responsiveness to DBcAMP and E2 and the loss of pituitary cyclicity in the aged female rat may be causally related.

Effects of trenbolone acetate and testosterone on growth and on plasma concentrations of corticosterone and ACTH in rats

1990 ◽  
Vol 126 (3) ◽  
pp. 461-466 ◽  
Author(s):  
M. N. Sillence ◽  
R. G. Rodway
Keyword(s):  
Weight Gain ◽  
Growth Response ◽  
Plasma Concentrations ◽  
Female Rats ◽  
Male Rats ◽  
Adrenal Weight ◽  
Trenbolone Acetate ◽  
Male And Female Rats ◽  
Age Related ◽  
Old Rats

ABSTRACT The effects of trenbolone acetate (TBA) on growth and on plasma concentrations of corticosterone were examined in male and female rats. At 5 weeks of age, rats were injected with TBA (0·8 mg/kg) dissolved in peanut oil, or with oil alone, daily for 10 days. In female rats, TBA caused an increase in weight gain (20–38%), a reduction in adrenal weight (19%) and a reduction in plasma concentrations of corticosterone (55%). In contrast, TBA-treated male rats showed no significant increase in weight gain, no significant change in adrenal weight and no reduction in plasma concentrations of corticosterone. The mechanism by which adrenal activity was suppressed in TBA-treated female rats was examined and the response compared with that to testosterone. Female rats (8 weeks old) were injected daily either with oil vehicle, TBA (0·8 mg/kg) or testosterone propionate (0·8 mg/kg). Testosterone increased weight gain (24%), but the growth response to TBA treatment was significantly greater (97%). A reduction in plasma concentrations of corticosterone (45%) was again observed in response to TBA. However, testosterone increased plasma concentrations of corticosterone (52%) above those of control values. Neither androgen affected plasma concentrations of ACTH. Finally, the effects of TBA were examined in 6-week-old female rats, to characterize further the apparent age-related increase in responsiveness. The growth response of 6-week-old rats (60–74%) was intermediate between that seen in 5- and 8-week-old animals. It is concluded that part of the anabolic activity of TBA may be related to a reduction in circulating concentrations of corticosterone. The effect of TBA on corticosterone concentrations differs from that of the natural androgen, testosterone, and does not appear to be mediated by a reduction in plasma concentrations of ACTH. Journal of Endocrinology (1990) 126, 461–466

Cold-induced thermogenesis in younger and older Fischer 344 rats following exercise training

1988 ◽  
Vol 254 (6) ◽  
pp. R908-R916 ◽  
Author(s):  
R. B. McDonald ◽  
B. A. Horwitz ◽  
J. S. Stern
Keyword(s):  
Exercise Training ◽  
Body Mass ◽  
Cold Exposure ◽  
O2 Consumption ◽  
Fischer 344 ◽  
Before And After ◽  
Old Rats ◽  
F344 Rats ◽  
Maintain Body Temperature ◽  
Brown Fat Mitochondria

The inability of old rats to maintain body temperature during cold exposure has been well documented. This study evaluated the effect of exercise on the rates of cold-induced O2 consumption and the contribution of nonshivering thermogenesis (NST) to these rates. Younger (12 mo) and older (24 mo) male Fischer 344 (F344) rats were divided into exercised and sedentary groups. Exercised rats were run on a motor-driven treadmill 60 min/day, at 19-24 m/min, 5 days/wk for 6 mo. At the conclusion of the 6-mo training period, O2 consumption of all four groups was measured at thermoneutrality (26 degrees C) and during 6 h of exposure to 6 degrees C. Rectal temperatures were recorded before and after cold exposure. NST was estimated from the ability of isolated brown fat mitochondria to bind guanosine 5'-diphosphate (GDP). Core temperature of older sedentary rats fell 5.1 +/- 0.4 degrees C after cold exposure (36.3 +/- 0.3 vs. 31.2 +/- 0.8 degrees C). Exercise training in older animals prevented this fall from occurring (36.4 +/- 0.2 vs. 35.3 +/- 0.3 degrees C). Core temperatures of cold-exposed younger exercised and sedentary rats did not differ from thermoneutral values. Exercise did not alter the rates of resting body mass-independent (ml.min-1.kg body mass-0.67) O2 consumption in younger or older rats. However, body mass-independent and lean body mass (LBM)-independent (ml.min-1.g LBM-0.67) cold-induced O2 consumptions of older exercised rats were significantly elevated relative to those of older sedentary animals. This effect of exercise was not seen in younger rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Overexpression of PKC-βI and -δ contributes to higher PKC activity in the proximal tubules of old Fischer 344 rats

2003 ◽  
Vol 285 (6) ◽  
pp. F1100-F1107 ◽  
Author(s):  
Mohammad Asghar ◽  
Tahir Hussain ◽  
Mustafa F. Lokhandwala
Keyword(s):  
Skf 38393 ◽  
Proximal Tubules ◽  
Fischer 344 Rats ◽  
Adult Rats ◽  
Altered Expression ◽  
Fischer 344 ◽  
Pkc Isoforms ◽  
Diuretic Response ◽  
Old Rats ◽  
Pkc Ζ

Previously, we reported that natriuretic and diuretic response to dopamine is diminished in old Fischer 344 rats, which is due to higher basal protein kinase C (PKC) activity and hyperphosphorylation of Na-K-ATPase in the proximal tubules (PTs) of old rats. The present study was conducted to determine whether higher PKC activity could be due to altered expression of some of the PKC isoforms in the superficial cortex (rich in PTs) of old rats. Fluorimetric measurement showed almost twofold increase in the PKC activities in homogenates and membranes of old (24 mo) compared with adult (6 mo) rats. Interestingly, in the basal state PKC-βI was overexpressed in the membranes, whereas PKC-δ expression was increased in the cytosol of old compared with adult rats. Treatment of the cortical slices with either SKF-38393, a D1-like agonist, or PDBu, a direct activator of PKC, caused translocation of PKC-βI from cytosol to membranes in adult but not in old rats. Both of these drugs caused translocation of PKC-δ from membranes to cytosol in adult but not in old rats. These drugs had no effect on translocation of PKC-ζ in both adult and old rats. Both PKC-βI and -δ coimmunoprecipiated with α1-subunit of Na-K-ATPase in adult and old rats. These observations suggest that both SKF-38393 and PDBu differentially regulate PKC-βI and -δ in adult but not in old rats. Also, PKC-βI and -δ seem to interact with Na-K-ATPase in these animals. The overexpression of both PKC-βI and -δ in old rats could be responsible for a higher basal PKC activity, which causes the hyperphosphorylation of Na-K-ATPase and contributes to the diminished inhibition of Na-K-ATPase activity by dopamine in old rats.

Aging induces muscle-specific impairment of endothelium-dependent dilation in skeletal muscle feed arteries

2002 ◽  
Vol 93 (5) ◽  
pp. 1685-1690 ◽  
Author(s):  
Christopher R. Woodman ◽  
Elmer M. Price ◽  
M. Harold Laughlin
Keyword(s):  
Skeletal Muscle ◽  
Mrna Expression ◽  
Vascular Function ◽  
Fischer 344 ◽  
Old Rats ◽  
The Right ◽  
Oxide Synthase ◽  
Endothelial Nitric Oxide ◽  
Feed Arteries ◽  
Skeletal Muscle Feed Arteries

We tested the hypothesis that aging decreases endothelium-dependent vasodilation in feed arteries perfusing rat skeletal muscle. In addition, we tested the hypothesis that attenuated vasodilator responses are associated with decreased endothelial nitric oxide synthase (eNOS) and superoxide dismutase-1 (SOD-1) expression. Soleus feed arteries (SFA) and gastrocnemius feed arteries (GFA) were isolated from young (4 mo) and old (24 mo) male Fischer 344 rats. Feed arteries from the right hindlimb were cannulated with two glass micropipettes for examination of endothelium-dependent [acetylcholine (ACh)] and endothelium-independent [adenosine (Ado) or sodium nitroprusside (SNP)] vasodilator function. Feed arteries from the left hindlimb were frozen and used to assess eNOS and SOD-1 protein and mRNA expression. In SFA, endothelium-dependent dilation to ACh was reduced in old rats (0.9 ± 0.04 vs. 0.8 ± 0.03), whereas dilator responses to Ado and SNP were similar in SFA of young and old rats. In GFA, vasodilator responses to ACh, Ado, and SNP were not altered by age. eNOS and SOD-1 protein expression declined with age in SFA (−71 and −54%, respectively) but not in GFA. eNOS and SOD-1 mRNA expression were not altered by age in SFA or GFA. Collectively, these data indicate aging induces muscle-specific impairment of endothelium-dependent vascular function in SFA.

scholarly journals Are skeletally mature female rats a suitable model to study osteoporosis?

2012 ◽  
Vol 56 (4) ◽  
pp. 259-264 ◽  
Author(s):  
Claudia Cardoso Netto ◽  
Vivian Cristine Correia Vieira ◽  
Lizanka Paola Figueiredo Marinheiro ◽  
Sherry Agellon ◽  
Hope Weiler ◽  
...  
Keyword(s):  
Bone Metabolism ◽  
Type I Collagen ◽  
Biomechanical Properties ◽  
Mature Female ◽  
Female Rats ◽  
Suitable Model ◽  
Type I ◽  
Age Related ◽  
Female Wistar Rats ◽  
Old Rats

OBJECTIVE: To analyze if female Wistar rats at 56 weeks of age are a suitable model to study osteoporosis. MATERIALS AND METHODS: Female rats with 6 and 36 weeks of age (n = 8 per group) were kept over a 20-week period and fed a diet for mature rodents complete in terms of Ca, phosphorous, and vitamin D. Excised femurs were measured for bone mass using dual-energy x-ray absorptiometry, morphometry, and biomechanical properties. The following serum mar-kers of bone metabolism were analyzed: parathyroid hormone (PTH), osteocalcin (OC), osteoprotegerin (OPG), receptor activator of nuclear factor Κappa B ligand (RANKL), C-terminal peptides of type I collagen (CTX-I), total calcium, and alkaline phosphatase (ALP) activity. RESULTS: Rats at 56 weeks of age showed important bone metabolism differences when compared with the younger group, such as, highest diaphysis energy to failure, lowest levels of OC, CTX-I, and ALP, and elevated PTH, even with adequate dietary Ca. CONCLUSION: Rats at 26-week-old rats may be too young to study age-related bone loss, whereas the 56-week-old rats may be good models to represent the early stages of age-related changes in bone metabolism.

scholarly journals Analysis of Stress and Strain to Determine the Pressure Changes in Tight-Fitting Garment

2020 ◽  
Vol 20 (1) ◽  
pp. 49-55
Author(s):  
Nareerut Jariyapunya ◽  
Blažena Musilová
Keyword(s):  
Mechanical Properties ◽  
Mathematical Models ◽  
Initial Phase ◽  
Circumferential Stress ◽  
The Body ◽  
Stress And Strain ◽  
Laplace’S Law ◽  
Pressure Changes ◽  
The Relationship ◽  
Laplace's Law

AbstractBased on the mechanical properties of stretch fabrics and Laplace’s law, the mathematical models have been developed enabling one to determine the values of the relationship between the fabric strain and the circumferential stress depending on pressure and diameter of the body. The results obtained refer to the values of the parameters assessed for the initial phase of their exploitation, which allow us to preliminarily predict the values of these parameters.

scholarly journals The Effects of Aging on Indices of Oxidative Stress and Apoptosis in the Female Fischer 344/Nnia X Brown Norway/BiNia Rat Heart

2013 ◽  
Vol 7 (1) ◽  
pp. 113-121 ◽  
Author(s):  
Jacqueline Fannin ◽  
Kevin M. Rice ◽  
Srininvas Thulluri ◽  
Ravi Kumar Arvapalli ◽  
Paulette Wehner ◽  
...  
Keyword(s):  
Superoxide Anion ◽  
Caspase 3 ◽  
Nitrosative Stress ◽  
Descriptive Study ◽  
Female Rats ◽  
Brown Norway ◽  
Rodent Models ◽  
Fischer 344 ◽  
Stress Markers ◽  
Effects Of Aging

Oxidative-nitrosative stress may play a role in age-associated cardiovascular disease as implied by recent studies.However, limited research has been conducted using aged female rodent models. In this study, we examined hearts obtained from 6-, 26-, and 30-month old female Fischer 344/Nnia x Brown Norway/BiNia (F344xBN) rats in order to examine how aging affects levels of cardiac oxidative-nitrosative stress and apoptosis. Oxidative (superoxide anion and 4-HNE) and nitrosative (protein nitrosylation) stress markers were increased 180 ± 17 %, 110 ± 3 %, and 14 ± 2 %, respectively in 30-month hearts compared to the hearts of 6-month female rats. Coincident with these changes in oxidative-nitrosative stress, aging was also found to be associated with increases in the number of Tdt-mediated dUTP nick labeling (TUNEL)-positive cardiomyocytes, alterations in the Bax/Bcl-2 ratio, and elevated cleavage of caspase-3. Regression analysis demonstrates significant correlation in the age-associated changes markers of oxidative–nitrosative stress with changes in apoptotic signaling. The findings from this descriptive study imply that age-associated increases in mitochondrial-mediated apoptosis may be associated with the increase in oxidative-nitrosative stress in the aging F344xBN female heart.

Sign in / Sign up

Export Citation Format

Share Document