Effect of age on renal conservation of phosphate in the rat

1986 ◽  
Vol 251 (3) ◽  
pp. F399-F407 ◽  
Author(s):  
G. M. Kiebzak ◽  
B. Sacktor
Keyword(s):  
Age Groups ◽  
Membrane Vesicles ◽  
Fractional Excretion ◽  
Renal Handling ◽  
Pi Transport ◽  
Age Related ◽  
Renal Brush Border Membrane ◽  
Low Phosphorus ◽  
Old Rats ◽  
Effect Of Age

Renal handling of phosphate (Pi) was examined in male Wistar-derived rats, 2-3, 6, 12, 18, and 24 mo of age. We observed a significant age-related phosphaturia [i.e., elevated urinary excretion (UPi V) and fractional excretion (FEPi)] in rats fed a normal phosphorus diet (NPD; 0.5% Pi). Concomitantly, plasma Pi decreased significantly and progressively with age. The mechanism of this age-related decrement in Pi conservation was examined by determining the initial (5 s) rate of Na+ gradient-dependent uptake of Pi in renal brush-border membrane vesicles (BBMV). Pi uptake significantly declined with increasing age. No consistent age-related decrease was seen in the Na+ gradient-dependent uptakes of glucose and proline by the same BBMV preparations, demonstrating the specificity of the Pi transport decrement. Pi transport kinetics revealed a significant age-related decrease in Vmax. No difference in Km of Pi was seen between age groups. These kinetic findings suggest either a decreased number of Pi carriers or decreased turnover of Pi carriers. Elevated parathyroid hormone did not explain the alteration in Pi conservation since urinary cAMP was not elevated in the intact senescent rat, and Pi uptake was not normalized in 24-mo-old rats 3 days after parathyroidectomy. The senescent 24-mo-old rat as well as the young adult 6-mo-old animal adapted to a low-phosphorus diet (LPD; 0.1% Pi) with a striking (greater than 100%) increase in Pi uptake by BBMV compared with NPD. thus the senescent kidney retained the capacity to respond appropriately to a LPD.(ABSTRACT TRUNCATED AT 250 WORDS)

Longitudinal force and stress of rat's esophagus: age-related changes.

1977 ◽  
Vol 232 (6) ◽  
pp. E580
Author(s):  
M P Zabinski ◽  
P Biancani
Keyword(s):  
Age Groups ◽  
Longitudinal Direction ◽  
Longitudinal Force ◽  
Active Stress ◽  
Length Relationship ◽  
Age Related ◽  
Old Rats ◽  
The Difference

Longitudinal force-length relationship of the rat esophagus was studied in vitro in three age groups: 1 mo, 3 mo, and 12 mo. The length of maximum force development (MFD) occurs at 1.4-1.5 times the in vivo length for all age groups. The active force developed at MFD increases markedly with age. The difference in the active forces in the 3-mo and 12-mo age groups is due to differences in cross section because the active stress of the esophagus in the longitudinal direction is approximately equal for the two age groups. The active stress in the 1-mo-old rats is lower than in the 3-mo-old rats, suggesting an increased contractility of the esophagus with age in this period of development.

Glutathione metabolism in heart and liver of the aging rat

1994 ◽  
Vol 72 (1-2) ◽  
pp. 58-61 ◽  
Author(s):  
M. Stio ◽  
T. Iantomasi ◽  
F. Favilli ◽  
P. Marraccini ◽  
B. Lunghi ◽  
...  
Keyword(s):  
Rat Heart ◽  
Reduced Glutathione ◽  
Age Groups ◽  
Glutathione Metabolism ◽  
Oxidized Glutathione ◽  
Glutathione S Transferase ◽  
Age Related ◽  
Glutamylcysteine Synthetase ◽  
Old Rats ◽  
Glucose 6 Phosphate Dehydrogenase

A comprehensive study on glutathione metabolism in rat heart and liver as a function of age was performed. In the heart, reduced glutathione, total glutathione, and the glutathione redox index showed a decrease during aging, while oxidized glutathione levels increased in 5-month-old rats with respect to the young animals and remained quite constant in 14- and 27-month-old rats. In the liver, the highest levels of reduced glutathione were found in the 2-month-old rats, while oxidized glutathione reached a peak at 5 months. Glutathione-associated enzymes showed age-related changes. Glutathione peroxidase, unaffected by aging in the heart, decreased in the liver of the 27-month-old rats. In the heart and the liver, the highest values of glutathione S-transferase were found at 5 months and 27 months, respectively. Glucose-6-phosphate dehydrogenase followed a similar trend in both heart and liver. Glutathione reductase also showed the same behaviour in heart and in liver, increasing in old rats with respect to the other age groups. A decrease in γ-glutamylcysteine synthetase was found in the heart and liver of 27-month-old rats in comparison with the 2-month-old ones. In conclusion, a decreased antioxidant capability has been demonstrated in both heart and liver of old rats.Key words: glutathione metabolism, age, rat heart, rat liver.

Effect of age on induction of hepatic phosphoenolpyruvate carboxykinase by fasting

1994 ◽  
Vol 267 (2) ◽  
pp. G195-G200 ◽  
Author(s):  
H. Van Remmen ◽  
W. F. Ward
Keyword(s):  
G Protein ◽  
Time Course ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Age Groups ◽  
Fischer 344 Rats ◽  
Fischer 344 ◽  
Fasting And Refeeding ◽  
Old Rats ◽  
Rate Limiting ◽  
Effect Of Age

This study examines the effect of age on the induction of the rate-limiting enzyme in gluconeogenesis, phosphoenolpyruvate carboxykinase (PEPCK), in response to fasting and refeeding in male Fischer 344 rats aged 3-18 mo. The rats were fasted for 30 h to increase the activity of PEPCK and subsequently were refed for 24 h to lower activity toward basal levels. PEPCK activity increased 2.2-fold in the 3-mo-old rats and 2.3-fold in the 18-mo-old rats during the 30-h fast. Therefore PEPCK induction during the 30-h fast was not altered with age. Similarly, refeeding resulted in a significant decrease in PEPCK activity at all ages. After the 24-h refeeding period, the rats were fasted a second time, and the time course of induction from the basal refed level was measured. In the young rats (6 mo), the activity of PEPCK increased rapidly from 18.12 +/- 1.61 to 42.66 +/- 5.94 U/g protein (P < 0.01) within 8 h of fasting. However, in the 18-mo-old rats, the initiation of the induction of PEPCK activity was delayed, and, after 12 h, PEPCK activity had increased from 17.34 +/- 1.34 to only 32.50 +/- 3.21 U/g protein (P < 0.01). Furthermore, the rate of induction appears to be decreased in the older animals. The activity after 24 h of fasting was equivalent in all four age groups (ranging from 44.72 +/- 5.38 at 3 mo to 40.18 +/- 5.42 U/g protein at 18 mo).(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensin II enhances β-adrenergic receptor-mediated vasorelaxation in aortas from young but not old rats

2000 ◽  
Vol 279 (6) ◽  
pp. H2807-H2814 ◽  
Author(s):  
William E. Schutzer ◽  
Hong Xue ◽  
John F. Reed ◽  
Jean-Baptiste Roullet ◽  
Sharon Anderson ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Adrenergic Receptor ◽  
Age Groups ◽  
Ang Ii ◽  
Camp Production ◽  
Fischer 344 ◽  
Age Related ◽  
Old Rats ◽  
Potent Vasoconstrictor ◽  
Direct Activator

β-Adrenergic receptor (β-AR)-mediated (cAMP-dependent) vasorelaxation declines with advancing age. It has been shown that angiotensin II (ANG II), a potent vasoconstrictor, enhances cAMP-mediated vasorelaxation. Therefore, we questioned whether ANG II could reverse age-related, impaired β-AR-mediated vasorelaxation and cAMP production. Pretreatment of aortic rings from 6-wk-old or 6-mo-old male Fischer 344 rats with ANG II significantly enhanced vasorelaxation induced by isoproterenol (Iso), a β-AR agonist, and forskolin, a direct activator of adenylyl cyclase, but not dibutyryl-cAMP or isobutylmethylxanthine. The ANG II effect was blocked by losartan but not PD-123319 and was not observed in the aortas from 12- and 24-mo-old animals. Iso-stimulated cAMP production in the aorta was enhanced in the presence of ANG II in the 6-wk-old and 6-mo-old age groups only. Results suggest ANG II cannot reverse the age-related impairment in β-AR-dependent vasorelaxation. We conclude aging may affect a factor common to both ANG II-receptors and β-AR signaling pathways or aging may impair cross-talk between these two receptor pathways.

Uptake of Pi in brush border vesicles after release of unilateral ureteral obstruction

1982 ◽  
Vol 243 (1) ◽  
pp. F29-F35
Author(s):  
S. Weinreb ◽  
K. A. Hruska ◽  
S. Klahr ◽  
M. R. Hammerman
Keyword(s):  
Brush Border ◽  
Ureteral Obstruction ◽  
Membrane Vesicles ◽  
Fractional Excretion ◽  
Unilateral Ureteral Obstruction ◽  
Renal Tubular Cells ◽  
Pi Transport ◽  
Renal Tubular ◽  
And Control

After release of complete unilateral ureteral obstruction, a decreased fractional excretion of phosphate (Pi) is observed in the postobstructed kidney compared with the nonobstructed (control) kidney. To determine whether this decrease in the urinary excretion of Pi is due to changes in Na+-dependent Pi transport across the renal brush border membranes of postobstructed and control kidneys, membrane vesicles were prepared from the brush borders of kidneys from dogs that had undergone complete unilateral ureteral obstruction. Alkaline phosphatase activity was decreased in membrane vesicles isolated from postobstructed kidneys. No differences were observed in Na+-dependent Pi transport or in Na+ uptake in membrane vesicles isolated from postobstructed as compared with control kidneys. The in vivo administration of parathyroid hormone decreased Na+-dependent Pi transport in membrane vesicles isolated from postobstructed and control kidneys despite the absence of a phosphaturic response. Our findings suggest that no intrinsic change in the transport characteristics of Pi across the luminal membrane of renal tubular cells occurs with unilateral ureteral obstruction. The findings are consistent with the suggestion that the low fractional excretion of Pi in the postobstructed kidney results from very low filtered loads of Pi on the postobstructed side.

scholarly journals Age-Related Frontal Hyperactivation Observed across Different Working Memory Tasks: An fMRI Study

2012 ◽  
Vol 25 (4) ◽  
pp. 351-361 ◽  
Author(s):  
Mohammad Fakhri ◽  
Hajir Sikaroodi ◽  
Farid Maleki ◽  
Mohammad Ali Oghabian ◽  
Hosein Ghanaati
Keyword(s):  
Working Memory ◽  
Age Groups ◽  
Auditory Task ◽  
Activation Patterns ◽  
Age Related ◽  
Feature Processing ◽  
Fmri Study ◽  
Potential Impact ◽  
Effect Of Age ◽  
Compensatory Effort

Purpose:To evaluate patterns of activation, convergence and divergence of three functional magnetic resonance imaging (fMRI) Working Memory (WM) tasks in two different age groups. We want to understand potential impact of task and subjects’ age on WM activations as well as most important areas with regard to WM functions.Materials and methods:Thirty-five healthy volunteers completed visual, verbal, and novel auditory WM tasks. The subjects were selected from age extremes to depict possible impact of normal aging. The General Linear Model was used to report significant activations and the effect of age group. Contrasts revealed differences in activation between tasks, and Combined Task Analysis was performed to determine common regions of activation across tasks.Results:Most of the observed differences between the tasks were seen in areas that were responsible for feature processing. Frontal regions were mainstay activation areas, regardless of the utilized stimulus. We found an age-related reduction in activity of visual (in visually-presented tasks) and auditory (in auditory task) cortices but an age-related increase in prefrontal cortex for all tasks.Conclusion:Regardless of the type of the task stimuli, frontal regions are the most important activation areas in WM processing. These areas are also main targets of age-related changes with regard to activation patterns. Our results also indicate that prefrontal overactivity in working memory might be a compensatory effort to mask age-related decline in sensory processing.

scholarly journals Giving vs. losing: age differences in decisions about charitable donations

2021 ◽  
Author(s):  
Erika Sparrow
Keyword(s):  
Age Differences ◽  
Intertemporal Choice ◽  
Age Groups ◽  
Younger Adults ◽  
Healthy Older Adults ◽  
Age Related ◽  
Financial Decision ◽  
Gains And Losses ◽  
Effect Of Age ◽  
Related Increase

In addition to making decisions about gains and losses that affect only ourselves, often in life we make decisions that benefit others. Research on lifespan changes in motivation suggests that altruistic motives become stronger with age. However, few studies have explored the effect of age on decisions that affect others. The current study used a realistic financial decision making task involving choices for gains, losses, and donations. Each decision involved an intertemporal choice, in which the participant selected either a smaller-sooner or a larger-later option that could affect their bonus payout. Participants included 36 healthy younger adults (M = 25.1 years) and 36 healthy older adults (M = 70.4 years). Both age groups chose more larger-later donations than larger-later losses, but the magnitude of this effect was amplified in older relative to younger adults. These findings suggest that intertemporal choices may be sensitive to an age-related increase in altruistic motivation

scholarly journals Giving vs. losing: age differences in decisions about charitable donations

2021 ◽  
Author(s):  
Erika Sparrow
Keyword(s):  
Age Differences ◽  
Intertemporal Choice ◽  
Age Groups ◽  
Younger Adults ◽  
Healthy Older Adults ◽  
Age Related ◽  
Financial Decision ◽  
Gains And Losses ◽  
Effect Of Age ◽  
Related Increase

In addition to making decisions about gains and losses that affect only ourselves, often in life we make decisions that benefit others. Research on lifespan changes in motivation suggests that altruistic motives become stronger with age. However, few studies have explored the effect of age on decisions that affect others. The current study used a realistic financial decision making task involving choices for gains, losses, and donations. Each decision involved an intertemporal choice, in which the participant selected either a smaller-sooner or a larger-later option that could affect their bonus payout. Participants included 36 healthy younger adults (M = 25.1 years) and 36 healthy older adults (M = 70.4 years). Both age groups chose more larger-later donations than larger-later losses, but the magnitude of this effect was amplified in older relative to younger adults. These findings suggest that intertemporal choices may be sensitive to an age-related increase in altruistic motivation

Gβ regulation of Na/H exchanger-3 activity in rat renal proximal tubules during development

2000 ◽  
Vol 278 (4) ◽  
pp. R931-R936 ◽  
Author(s):  
Xiao Xi Li ◽  
Frederick E. Albrecht ◽  
Jean E. Robillard ◽  
Gilbert M. Eisner ◽  
Pedro A. Jose
Keyword(s):  
G Protein ◽  
Second Messengers ◽  
Membrane Vesicles ◽  
Inhibitory Effect ◽  
Protein Subunit ◽  
Adult Rats ◽  
Renal Brush Border Membrane ◽  
Sodium Hydrogen Exchanger ◽  
Old Rats ◽  
Renal Tubular

The decreased natriuretic action of dopamine in the young has been attributed to decreased generation of cAMP by the activated renal D1-like receptor. However, sodium/hydrogen exchanger (NHE) 3 activity in renal brush-border membrane vesicles (BBMV) can be modulated independent of cytoplasmic second messengers. We therefore studied D1-like receptor regulation of NHE activity in BBMVs in 2-, 4-, and 12-wk-old (adult) rats. Basal NHE activity was least in 2-wk-old compared with 4- and 12-wk-old rats. D1-like agonist (SKF-81297) inhibition of NHE activity was also least in 2-wk-old (−1 ± 9%, n = 3) compared with 4 (−15 ± 5%, n = 6)- and 12 (−65 ± 4%, n = 6)-wk-old rats. The decreased response to the D1-like agonist in BBMV was not caused by decreased D1 receptors or NHE3 expression in the young. Gsα, which inhibits NHE3 activity by itself, coimmunoprecipitated with NHE3 to the same extent in 2-wk-old and adult rats. Gsα function was also not impaired in the young because guanosine 5′- O-(3-thiotriphosphate) decreased NHE activity to a similar extent in 4-wk-old and adult rats. Gαi-3 protein expression in BBMV also did not change with age. In contrast, Gβ expression and the amount of Gβ that coimmunoprecipitated with NHE3 in BBMV was greatest in 2-wk-old rats and decreased with age. Gβ common antibodies did not affect D1-like agonist inhibition of NHE activity in adult rats (8%) but markedly increased it (48%)in 4-wk-old rats. We conclude that the decreased inhibitory effect of D1-like receptors on NHE activity in BBMV in young rats is caused, in part, by the increased expression and activity of the G protein subunit Gβ/γ. The direct regulation of NHE activity by G protein subunits may be an important step in the maturation of renal tubular ion transport.

scholarly journals Age-related changes in plasma lycopene concentrations, but not in vitamin E, are associated with fat mass

2000 ◽  
Vol 84 (5) ◽  
pp. 711-716 ◽  
Author(s):  
Pascal Grolier ◽  
Yves Boirie ◽  
Evelyne Levadoux ◽  
Marion Brandolini ◽  
Patrick Borel ◽  
...  
Keyword(s):  
Vitamin E ◽  
Fat Mass ◽  
Plasma Cholesterol ◽  
Age Groups ◽  
The Elderly ◽  
Fat Free Mass ◽  
Plasma Vitamin ◽  
Tocopherol Concentration ◽  
Age Related ◽  
Effect Of Age

The aim of the present study was to assess the influence of age on plasma concentration of α-tocopherol, retinol and carotenoids with a special attention paid to natural differences in body composition. Forty healthy subjects were recruited: twenty were less than 35 years old and twenty above 60 years old. Males and females were equally represented in each age group. Subjects were kept in energy balance and received controlled diets for 36 h. Fat mass and fat-free mass were determined with the180-enriched water dilution technique. Plasma vitamins A and E, and carotenoid levels were determined after 12 h fasting and were shown to be similar in women and men. Plasma α-tocopherol concentration increased with age (+44 % elderlyv.young), and correlated with % fat mass and plasma cholesterol. After adjustment for plasma cholesterol, the effect of age and % fat mass disappeared. In contrast, plasma lycopene level was 2-fold lower in the elderly than in the young group, and was inversely correlated with fat mass. When lycopene values were adjusted for fat mass, the effect of age disappeared. These results suggest that plasma levels of vitamin E and lycopene differed in the two age groups and that differences in plasma cholesterol and fat mass might participate in such an effect. Short-term vitamin intake did not appear to influence plasma vitamin concentrations.

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