scholarly journals Brain buffering is restored in hyponatremic rats by correcting their plasma sodium concentration.

1994 ◽  
Vol 5 (1) ◽  
pp. 85-92
Author(s):  
S Adler ◽  
J G Verbalis ◽  
D Williams
Keyword(s):  
Late Phase ◽  
Sodium Concentration ◽  
Liquid Diet ◽  
Plasma Sodium ◽  
Free Access ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Complete Restoration ◽  
Brain Ph ◽  
Hydrogen Ion Transport

Previous studies from this laboratory showed that both acute and chronic hyponatremia impaired active brain buffering. These studies were performed to determine whether correcting the plasma sodium restored normal buffering in hyponatremic rats. Acute (1- and 2-day) and chronic (7- and 14-day) hyponatremia was induced in male Sprague-Dawley rats by constant desmopressin administration combined with a liquid diet. Plasma sodium was corrected by stopping desmopressin for 6 h, substituting solid chow, and allowing free access to water. Studies were performed 24 h later. Uncorrected hyponatremic rats who continued to receive desmopressin and liquid diet served as controls. Brain pH was determined by [31P]NMR in rats anesthetized with N2O and paralyzed with pancuronium. Brain buffering was determined by the response to CO2 loading. Resting brain pH was the same in corrected and uncorrected rats, but the two groups responded differently to CO2 loading. Thus, 55 min after ventilation with 20% CO2, corrected rat brain pH was 0.13 pH units higher than in uncorrected rats despite statistically similar changes in CO2 tension and arterial pH in both groups. Moreover, 15 min into recovery from CO2 exposure, brain pH in corrected rats overshot resting pH by 0.07, whereas no overshoot occurred in uncorrected rats. Buffering in corrected rats was identical to that shown previously in normonatremic rats. The complete restoration of late-phase buffering achieved by normalizing the plasma sodium of hyponatremic rats indicates that at least some portion of active hydrogen ion transport is sodium dependent in the brain.

scholarly journals Energetics and mammary carcinogenesis: effects of moderate-intensity running and energy intake on cellular processes and molecular mechanisms in rats

2009 ◽  
Vol 106 (3) ◽  
pp. 911-918 ◽  
Author(s):  
Zongjian Zhu ◽  
Weiqin Jiang ◽  
John N. McGinley ◽  
Henry J. Thompson
Keyword(s):  
Cell Cycle Progression ◽  
Molecular Mechanisms ◽  
Mammary Carcinogenesis ◽  
Mitochondrial Pathway ◽  
Moderate Intensity ◽  
Free Access ◽  
Sprague Dawley ◽  
Cellular Processes ◽  
Sprague Dawley Rats ◽  
Induced Apoptosis

The objective of this experiment was to determine the effects on mammary carcinogenesis of similar limitations in energy availability either by energy expenditure due to moderate-intensity running (physical activity, PA) or by regulating dietary energy (RE) intake relative to a sedentary control (SC) group that ate ad libitum. A total of 90 female Sprague-Dawley rats were injected with 1-methyl-1-nitrosourea (50 mg/kg) and 7 days thereafter were randomized to either SC, a PA group given free access to a motorized running wheel, or a RE group whose food intake limited growth to the rate observed in PA. Compared with SC, mammary carcinogenesis was inhibited by RE or PA. Cancer incidence, 92.6%, 77.8%, and 66.7% ( P = 0.06), and cancer multiplicity, 3.44, 2.11, and 1.62 cancers/rat ( P = 0.006), in SC, RE, and PA, respectively, were reduced to a similar extent by RE and PA. Histological and Western blot analyses of mammary carcinomas provided evidence that RE and PA induced apoptosis via the mitochondrial pathway, that cell cycle progression was suppressed at the G1/S transition, and that intratumoral blood vessel density was reduced, although it remains to be determined whether PA and RE exert these effects via the same mechanisms.

Sex differences in ethanol liquid diet consumption in Sprague–Dawley rats

Alcohol ◽  
2005 ◽  
Vol 35 (2) ◽  
pp. 113-118 ◽  
Author(s):  
Mariann R. Piano ◽  
Timothy M. Carrigan ◽  
Dorie W. Schwertz
Keyword(s):  
Sex Differences ◽  
Liquid Diet ◽  
Sprague Dawley ◽  
Sprague Dawley Rats

Effects of 4-h ischemia and 1-h reperfusion on rat muscle sarcoplasmic reticulum function

2001 ◽  
Vol 281 (4) ◽  
pp. E867-E877 ◽  
Author(s):  
R. Tupling ◽  
H. Green ◽  
G. Senisterra ◽  
J. Lepock ◽  
N. McKee
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Phase 1 ◽  
Late Phase ◽  
Maximal Activity ◽  
Hill Coefficient ◽  
Sprague Dawley ◽  
Rapid Phase ◽  
Sprague Dawley Rats ◽  
The Hill

To investigate the hypothesis that ischemia and reperfusion would impair sarcoplasmic reticulum (SR) Ca2+ regulation in skeletal muscle, Sprague-Dawley rats ( n = 20) weighing 290 ± 3.5 g were randomly assigned to either a control control (CC) group, in which only the effects of anesthetization were studied, or to a group in which the muscles in one hindlimb were made ischemic for 4 h and allowed to recover for 1 h (I). The nonischemic, contralateral muscles served as control (C). Measurements of Ca2+-ATPase properties in homogenates and SR vesicles, in mixed gastrocnemius and tibialis anterior muscles, indicated no differences between groups on maximal activity, the Hill coefficient, and Ca50, defined as the Ca2+concentration needed to elicit 50% of maximal activity. In homogenates, Ca2+ uptake was lower ( P < 0.05) by 20–25%, measured at 0.5 and 1.0 μM of free Ca2+ ([Ca2+]f) in C compared with CC. In SR vesicles, Ca2+ uptake was lower ( P < 0.05) by 30–38% in I compared with CC at [Ca2+]f between 0.5 and 1.5 μM. Silver nitrate induced Ca2+ release, assessed during both the initial, early rapid ( phase 1), and slower, prolonged late ( phase 2) phases, in homogenates and SR vesicles, indicated a higher ( P < 0.05) release only in phase 1in SR vesicles in I compared with CC. These results indicate that the alterations in SR Ca2+ regulation, previously observed after prolonged ischemia by our group, are reversed within 1 h of reperfusion. However, the lower Ca2+ uptake observed in long-term, nonischemic homogenates suggests that altered regulation may occur in the absence of ischemia.

scholarly journals Effect of diaspirin cross-linked hemoglobin on normal and postischemic microcirculation of the rat pancreas

1999 ◽  
Vol 276 (6) ◽  
pp. G1507-G1514 ◽  
Author(s):  
Ernst von Dobschuetz ◽  
Tomas Hoffmann ◽  
Clemens Engelschalk ◽  
Konrad Messmer
Keyword(s):  
Detrimental Effect ◽  
Oxygen Carrier ◽  
Capillary Density ◽  
Control Group ◽  
Leukocyte Adherence ◽  
Sprague Dawley ◽  
Rat Pancreas ◽  
Sprague Dawley Rats ◽  
Pancreatic Ischemia ◽  
Complete Restoration

Microcirculatory alterations with reduced nutritive supply to the pancreas could be the cause of hyperamylasemia, which occurs in some patients receiving the vasoactive oxygen carrier diaspirin cross-linked hemoglobin (DCLHb) in clinical studies. Therefore, the effects of DCLHb on rat pancreas microcirculation were evaluated. Anesthetized Sprague-Dawley rats received one of the following treatments during baseline conditions ( n = 7 rats/group): 10% hydroxyethyl starch (HAES) (0.4 ml/kg), DCLHb (400 mg/kg), or DCLHb (1,400 mg/kg). After 1 h of complete, reversible pancreatic ischemia, other animals received 10% HAES (0.4 ml/kg) or DCLHb (400 mg/kg) during the onset of reperfusion. The number of red blood cell-perfused capillaries (functional capillary density, FCD) and the level of leukocyte adherence in postcapillary venules in the pancreas were assessed by means of intravital microscopy during 2 h after treatment. In the nonischemic groups, FCD was 18% greater after DCLHb (1,400 mg/kg) than after 10% HAES treatment without any increase in leukocyte adherence. In the inschemia-reperfusion (I/R) 10% HAES group, FCD was significantly ( P < 0.05) lowered, leukocyte adherence enhanced, and mean arterial pressure (MAP) reduced by 31% compared with nonischemic animals. DCLHb treatment in the I/R group resulted in a slight increase in FCD, a significant ( P < 0.05) reduction of leukocyte adherence, and a complete restoration of MAP compared with the animals of the I/R control group. Thus our data provide no evidence for a detrimental effect on the pancreatic microcirculation or an enhanced risk of postischemic pancreatitis by DCLHb.

Chronotropic, Inotropic and Dromotropic Parameters of the Heart and Oxidative Stress in Rats Receiving High Doses of Fructose

2019 ◽  
Vol 8 ◽  
pp. 1250
Author(s):  
Esmat Radmanesh ◽  
Mahin Dianat ◽  
Narges Atefipour
Keyword(s):  
Oxidative Stress ◽  
Risk Factors ◽  
Drinking Water ◽  
Control Group ◽  
Free Access ◽  
Qtc Interval ◽  
Sprague Dawley ◽  
Cvd Risk ◽  
Sprague Dawley Rats ◽  
High Doses

Background: Many risk factors, including nutritional ones, contribute to cardiovascular diseases (CVDs). Increased fructose consumption, for example, can lead to an increase in CVD risk factors, i.e. an increase in blood lipids and the development of insulin resistance. Materials and Methods: In the present study, Sprague Dawley rats were divided into two groups:  control group (free access to tap drinking water for seven weeks), and a group that received fructose 10% in drinking water for seven weeks, (n ═8 per each group). In all groups, before starting the test period and seven weeks after it, electrocardiogram was recorded by Power lab system. Unpaired t-test and two-way ANOVA were used for data analysis. Also, oxidative stress parameters were measured. Results: In the group received high doses of fructose, a significant reduction (P <0.05) was observed in the PR interval (P<0.001) and a significant increase (P<0.05) in the QTc interval. However, there was no significant change in the RR interval and the voltage of the QRS complex. A significant decrease in catalase, superoxide dismutase and glutathione peroxidase (P<0.05) and a significant increase (P<0.05) in malondialdehyde and lactate dehydrogenase were observed in the group that received fructose in comparison with the control group at the end of the experiment. Conclusion: According to our results, the chance of arrhythmias in the rats receiving high doses of fructose was possibly due to the increased oxidative stress in the healthy rats. [GMJ.2019;8:e1250]

Leptin-induced decrease in food intake is not associated with changes in gastric emptying in lean mice

1997 ◽  
Vol 272 (3) ◽  
pp. R1007-R1011 ◽  
Author(s):  
M. D. Barrachina ◽  
V. Martinez ◽  
J. Y. Wei ◽  
Y. Tache
Keyword(s):  
Gastric Emptying ◽  
Food Intake ◽  
Intraperitoneal Injection ◽  
Acute Effect ◽  
Free Access ◽  
Sprague Dawley ◽  
Single Intraperitoneal Injection ◽  
Recombinant Mouse ◽  
Purina Chow ◽  
Sprague Dawley Rats

Chronic treatment with leptin regulates body weight and energy balance and reduces food intake in obese and lean mice. In 18- to 20-h fasted lean mice (C57BL/6, +/+), we examined the acute effect of a single intraperitoneal injection of recombinant mouse leptin (0.12 mg/kg) on food intake and gastric emptying. Leptin reduced food intake, with a peak inhibition at the 5th h postinjection (69 +/- 12%/h), although there was no change in food consumption at the 1st h. Leptin did not alter the 4-h rate of gastric emptying of a solid nutrient meal (free access to Purina chow for either 1-, 2-, or 4-h period). In normal Sprague-Dawley rats fasted for 18-20 h, a single intraperitoneal injection of recombinant mouse leptin (0.2 or 1.2 mg/kg) did not modify the 7-h cumulative or hourly food intake. These results show that a single intraperitoneal injection of recombinant mouse leptin reduces food intake within 5 h while not influencing gastric emptying of ingested food in lean mice. Sprague-Dawley rats are unresponsive to the food intake-reducing effect of a single intraperitoneal injection of mouse leptin at a dose 10-fold higher than that shown to be effective in mice within the first 4-7 h postinjection.

Antihypertensive effect of progesterone in rats with mineralocorticoid-induced hypertension.

1979 ◽  
Vol 236 (4) ◽  
pp. E366 ◽  
Author(s):  
G Wambach ◽  
J R Higgins
Keyword(s):  
Phase I ◽  
Phase Ii ◽  
Hypotensive Effect ◽  
Sodium Concentration ◽  
Sprague Dawley ◽  
Spontaneously Hypertensive ◽  
Sprague Dawley Rats ◽  
Induced Hypertension ◽  
Blood Pressures ◽  
Induced Changes

Uninephrectomized, saline-fed male Sprague-Dawley rats were given DOCA 5 mg per week alone or together with progesterone 20 mg per week for 6 weeks (phase I). Subsequently, the doses of DOCA and progesterone were doubled and the rats were studied for an additional 6 wk (phase II). Progesterone prevented DOCA-induced hypertension during phase I. Phase II blood pressures were higher in DOCA-progesterone-treated animals than in controls, but remained lower than in animals treated with DOCA alone. At the end of phase II the animals were killed, and blood samples and skeletal muscle samples were taken for analysis of electrolyte content. DOCA-treated animals were found to have an increased rate of potassium excretion, an increase in muscle sodium concentration, and a decrease in muscle potassium concentration compared to the controls. Progesterone treatment significantly blunted the DOCA-induced changes in muscle electrolyte concentrations and increased the rate of sodium excretion. No hypotensive effect was observed when progesterone in doses similar to those of phase I was administered to spontaneously hypertensive rats. Thus, in experimental mineralocorticoid hypertension, the hypotensive effect of progesterone appears to correlate closely with its mineralocorticoid antagonistic properties.

scholarly journals Roux-en-Y gastric bypass in rats progressively decreases the proportion of fat calories selected from a palatable cafeteria diet

2016 ◽  
Vol 310 (10) ◽  
pp. R952-R959 ◽  
Author(s):  
Clare M. Mathes ◽  
Chanel Letourneau ◽  
Ginger D. Blonde ◽  
Carel W. le Roux ◽  
Alan C. Spector
Keyword(s):  
Gastric Bypass ◽  
Gastric Bypass Surgery ◽  
Food Selection ◽  
Caloric Intake ◽  
Free Access ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Sugar Levels ◽  
The Impact

Roux-en-Y gastric bypass surgery (RYGB) decreases caloric intake in both human patients and rodent models. In long-term intake tests, rats decrease their preference for fat and/or sugar after RYGB, and patients may have similar changes in food selection. Here we evaluated the impact of RYGB on intake during a “cafeteria”-style presentation of foods to assess if rats would lower the percentage of calories taken from fat and/or sugar after RYGB in a more complex dietary context. Male Sprague-Dawley rats that underwent either RYGB or sham surgery (Sham) were presurgically and postsurgically given 8-days free access to four semisolid foods representative of different fat and sugar levels along with standard chow and water. Compared with Sham rats, RYGB rats took proportionally fewer calories from fat and more calories from carbohydrates; the latter was not attributable to an increase in sugar intake. The proportion of calories taken from protein after RYGB also increased slightly. Importantly, these postsurgical macronutrient caloric intake changes in the RYGB rats were progressive, making it unlikely that the surgery had an immediate impact on the hedonic evaluation of the foods and strongly suggesting that learning is influencing the food choices. Indeed, despite these dietary shifts, RYGB, as well as Sham, rats continued to select the majority of their calories from the high-fat/high-sugar option. Apparently after RYGB, rats can progressively regulate their intake and selection of complex foods to achieve a seemingly healthier macronutrient dietary composition.

Long-Evans and Sprague-Dawley rats exhibit divergent responses to refeeding after caloric restriction

2005 ◽  
Vol 288 (6) ◽  
pp. R1468-R1476 ◽  
Author(s):  
S. A. Evans ◽  
M. M. Messina ◽  
W. D. Knight ◽  
A. D. Parsons ◽  
J. M. Overton
Keyword(s):  
Food Intake ◽  
Caloric Restriction ◽  
Sprague Dawley ◽  
Sd Rats ◽  
Sprague Dawley Rats ◽  
Complete Restoration ◽  
Ad Libitum ◽  
Long Evans ◽  
Strain Dependent ◽  
Stimulation Of

Mature male Sprague-Dawley (SD) and Long-Evans (LE) rats were instrumented with telemetry transmitters for measurement of heart rate (HR) and housed in room calorimeters for assessment of food intake and oxygen consumption (V̇o2) at standard laboratory temperatures (23°C) to examine physiological responses to caloric restriction (CR; 60% of baseline ad libitum calories for 2 wk) and refeeding. Ad libitum controls had stable food intake (84–88 kcal/day) and gained weight at rates of 3–4 g/day. Groups from both strains assigned to CR exhibited similar patterns of weight loss and reductions in V̇o2 and HR. Upon refeeding, SD rats exhibited a mild, transient hyperphagic response (1 day) accompanied by sustained suppression of V̇o2 and HR that remained evident 8 days after refeeding. In contrast, LE rats exhibited sustained daily hyperphagia that persisted 8 days after refeeding and was accompanied by a complete restoration of HR and V̇o2. The lower HR and V̇o2 observed during refeeding in SD rats were not due to reduced locomotor activity. The results reveal a strain-dependent divergent response to recovery from CR. We conclude that during recovery from CR, homeostatic stimulation of appetite or suppression of energy expenditure may occur selectively to restore body weight.

Testosterone, dihydrotestosterone, androstenedione and dehydroepiandrosterone concentrations in placentae, ovaries and plasma of the rat in late pregnancy

1984 ◽  
Vol 105 (1) ◽  
pp. 119-125 ◽  
Author(s):  
C. Legrand ◽  
J. Marie ◽  
J. P. Maltier
Keyword(s):  
Similar Pattern ◽  
Sharp Increase ◽  
Late Phase ◽  
Late Pregnancy ◽  
Sprague Dawley ◽  
Ovulatory Cycle ◽  
Peripheral Plasma ◽  
Sprague Dawley Rats

Abstract. Testosterone (T), dihydrotestosterone (DHT), androstenedione (Δ4) and dehydroepiandrosterone (DHA) were measured by radioimmunoassay in peripheral plasma, uterine vein plasma, ovary and placentae within the last 3–4 days of pregnancy in Sprague-Dawley rats. In the uterine vein, T and Δ4 levels were significantly higher than those reported in the peripheral plasma at any particular day of late pregnancy. In peripheral plasma as in uterine vein plasma Δ4 and T gradually decreased from day 20 to term (−63% for Δ4 and approximately −45% for T) whereas DHT concentrations were unchanged. This decline is concomitant with a similar pattern of change in the placentae; indeed placental concentrations of Δ4 and T decreased significantly from day 19 to 22 (−63 and −79%, respectively) and were positively correlated with the levels of both androgens in uterine venous and peripheral plasma. Thus it was concluded that in the late phase of pregnancy in the rat circulating Δ4 and T originate from placentae. In contrast, ovarian androgen concentrations showed a sharp increase from day 21 to term: 58% for DHA, 49% for Δ4, 87% for T and 24% for DHT. It is suggested that these increasing concentrations of ovarian androgens could be related to the next ovulatory cycle.

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