Androgen-mediated sex differences of cardiovascular responses in rats

1978 ◽  
Vol 235 (2) ◽  
pp. H242-H246 ◽  
Author(s):  
P. J. Baker ◽  
E. R. Ramey ◽  
P. W. Ramwell
Keyword(s):  
Sex Differences ◽  
Arachidonic Acid ◽  
Rank Order ◽  
Cardiovascular Responses ◽  
Sprague Dawley ◽  
Similar Treatment ◽  
Depressor Response ◽  
Sprague Dawley Rats ◽  
Significant Change ◽  
Dose Levels

Sex differences in the systemic depressor response to arachidonic acid (50 or 150 microgram/kg iv) were observed in intact and castrated anesthetized Sprague-Dawley rats. The rank order of responsiveness was: castrate males, castrate females, females, males; all four groups were significantly different (P less than 0.05) at the higher dose. Castrated males pretreated with testosterone (1 mg/kg sc) 5 or 7 days previously gave a response at the higher arachidonate dose levels that was of the same order as that obtained with intact males. Similar treatment of castrate males with androgen potentiated (P less than 0.05) the vasopressor action of norepinephrine (0.25 microgram/kg) on day 7 after the testosterone pretreatment. In contrast, treatment with depot estradiol (100 microgram/kg sc) in castrate males produced no significant change in the response to either of the vasoactive compounds on both days 5 and 7 after pretreatment. These data suggest that testosterone may be a significant factor in the development of sex differences in the cardiovascular systems of rats.

Intraneuronal accumulations of lysosomes in the cerebellum of rats and dogs after dosing with MDL-832

1990 ◽  
Vol 48 (3) ◽  
pp. 830-831
Author(s):  
S.D. Barnard ◽  
S.D. Warner
Keyword(s):  
Brown Pigment ◽  
Beagle Dogs ◽  
Sprague Dawley ◽  
Gelatin Capsules ◽  
Pigment Granules ◽  
Sprague Dawley Rats ◽  
Hematoxylin And Eosin ◽  
Dose Levels

1, 2, 9, 10-tetramethoxyaporphine phosphate (MDL-832) was once considered a potential human antitussive. MDL-832 was administered orally in the diets of Sprague-Dawley rats at dose levels of 0, 5, 10, 20, 40, 80 and 160 mg/kg/day for 3 and 6 months and in gelatin capsules to Beagle dogs at 0, 5, 10, 15, 30 and 60 mg/kg/day for 3, 6 and 12 months. Histopathologic examinations of hematoxylin and eosin-stained cerebellar sections revealed intracytoplasmic brown pigment accumulations in large fusiform neurons (presumably the motor type) of the pons. The pigment granules were found to be PAS-positive, non-acid fast, iron-free, Sudan B-positive and fuchsinophilic. Intraneuronal pigment accumulations were seen in rats after 3 months of treatment at 80 mg but not at 40 mg and after 6 months at 20 mg but not at 10 mg. For dogs the effect was observed after 3 months at 60 mg but not at 30 mg and after 12 months at 10 mg but not at 5 mg.

Changes in total body calcium balance with exercise in the rat

1983 ◽  
Vol 55 (1) ◽  
pp. 201-204 ◽  
Author(s):  
A. D. LeBlanc ◽  
H. J. Evans ◽  
P. C. Johnson ◽  
S. Jhingran
Keyword(s):  
Least Squares ◽  
Voluntary Exercise ◽  
Calcium Balance ◽  
Sprague Dawley ◽  
Total Body Calcium ◽  
Sprague Dawley Rats ◽  
Least Squares Fit ◽  
Significant Change ◽  
Total Body ◽  
And Control

The purpose of this study was to evaluate the effect of deconditioning on the total body calcium in rats. Two separate experiments were performed using female Sprague-Dawley rats, 187-266 days of age. Total body calcium was measured in experimental and control rats during and following several weeks of voluntary exercise. The slope from the least-squares fit of total body calcium with time was used to obtain an average calcium balance for each animal during each study period. In both groups the exercised rats had a significantly decreased calcium balance after cessation of exercise, whereas no significant change was seen in nonexercised controls. In both groups, the exercised animals gained calcium at a significantly greater rate than controls. Our findings indicate that while exercised rats may gain calcium at a faster rate compared with nonexercising controls, the rate of gain following cessation of exercise is less than the controls.

scholarly journals Transient Neonatal Cryptosporidium parvum Infection Triggers Long-Term Jejunal Hypersensitivity to Distension in Immunocompetent Rats

2006 ◽  
Vol 74 (7) ◽  
pp. 4387-4389 ◽  
Author(s):  
Rachel Marion ◽  
Asiya Baishanbo ◽  
Gilles Gargala ◽  
Arnaud François ◽  
Philippe Ducrotté ◽  
...  
Keyword(s):  
Cryptosporidium Parvum ◽  
Myeloperoxidase Activity ◽  
Sprague Dawley ◽  
Depressor Response ◽  
Sprague Dawley Rats

ABSTRACT In 5-day-old immunocompetent Sprague-Dawley rats infected with either 102 or 105 Cryptosporidium parvum oocysts, transient infection resulted 120 days later in increased cardiovascular depressor response to jejunal distension and jejunal myeloperoxidase activity (P < 0.05). Nitazoxanide treatment normalized jejunal sensitivity (P < 0.001) but not myeloperoxidase levels (P > 0.05). Data warrant further evaluation of the role of early cryptosporidiosis in the development of chronic inflammatory gut conditions.

Sex Differences in the Response of Rat Heart Ventricle to Calcium

2004 ◽  
Vol 5 (4) ◽  
pp. 286-298 ◽  
Author(s):  
Dorie W. Schwertz ◽  
Jenny M. Beck ◽  
Jill M. Kowalski ◽  
James D. Ross
Keyword(s):  
Sex Differences ◽  
Papillary Muscle ◽  
Contractile Response ◽  
Ventricular Myocytes ◽  
Ventricular Myocardium ◽  
Contractile Proteins ◽  
Therapeutic Interventions ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Whole Heart

Calcium (Ca2+ ) is a key mediator of myocardial function. Calcium regulates contraction, and disruption of myocellular Ca2+ handling plays a role in cardiac pathologies such as arrhythmias and heart failure. This investigation examines sex differences in sensitivity of the contractile proteins to Ca2+ and myofibrillar Ca2+ delivery in the ventricular myocardium. Sensitivity of contractile proteins to Ca2+ was measured in weight-matched male and female Sprague-Dawley rats using the skinned ventricular papillary muscle fiber and Ca2+ -stimulated Mg2+ -dependent adenosine triphosphatase (ATPase) activity methodologies. Calcium delivery was examined by measuring the contractile response to a range of extracellular Ca2+ concentrations in isolated ventricular myocytes, papillary muscle, and the isolated perfused whole heart. Findings from studies in the whole heart suggest that at a fixed preload, the male left ventricle generates more pressure than a female ventricle over a range of extracellular Ca2+ concentrations. In contrast, results from myocyte and papillary muscle studies suggest that females require less extracellular Ca2+ to elicit a similar contractile response. Results obtained from the 2 methods used to determine sex differences in Ca2+ sensitivity were equivocal. Further studies are required to elucidate sex differences in myocardial Ca2+ handling and the reasons for disparate results in different heart muscle preparations. The results of these studies will lead to the design of sex-optimized therapeutic interventions for cardiac disease.

Abstract P173: Sex Differences in the Diurnal Natriuretic Response to Benzamil in Sprague Dawley Rats

Hypertension ◽  
2018 ◽  
Vol 72 (Suppl_1) ◽  
Author(s):  
Reham H Soliman ◽  
Jermaine G Johnston ◽  
Eman Y Gohar ◽  
David M Pollock
Keyword(s):  
Sex Differences ◽  
Sprague Dawley ◽  
Sprague Dawley Rats

Adrenomedullin microinjection into the area postrema increases blood pressure

1997 ◽  
Vol 272 (6) ◽  
pp. R1698-R1703 ◽  
Author(s):  
M. A. Allen ◽  
P. M. Smith ◽  
A. V. Ferguson
Keyword(s):  
Blood Pressure ◽  
Area Postrema ◽  
Area Under The Curve ◽  
Physiological Role ◽  
Cardiovascular Responses ◽  
Hypotensive Effect ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Brain Site

Adrenomedullin (ADM) circulates in the blood at concentrations comparable to other vasoactive peptides with established roles in cardiovascular regulation. Intravenously administered ADM produces a clear hypotensive effect, whereas intracerebroventricular microinjections result in increases in blood pressure (BP). Recently, we demonstrated that ADM influences neurons of the area postrema (AP), a central nervous system site implicated in cardiovascular control. However, to address directly the physiological significance of the actions of ADM at the AP, an in vivo microinjection study was undertaken. ADM, at two concentrations (1 and 10 microM), in volumes of 50, 100, and 200 nl, was microinjected into the AP or NTS of 21 urethan-anesthetized male Sprague-Dawley rats. Microinjection of 10 microM ADM (100 nl) resulted in significant transient (2-5 min) increases in BP [120 s area under the curve (AUC): 684.3 +/- 268.6 mmHg/s (P < 0.05)], and heart rate (HR) [AUC: 12.5 +/- 4.5 beats/min (P < 0.05)]. The lower concentration of ADM (1 microM) had no effect on either BP (179.1 +/- 143.6 mmHg/s) or HR (0.8 +/- 2.6 beats/min). ADM was also microinjected into the immediately adjacent nucleus of the solitary tract, where it was found to be without effect on either BP or HR. This study demonstrates, for the first time, a physiological role for ADM acting at a specific brain site, the AP, to produce significant cardiovascular responses.

scholarly journals Mechanism of Erythropoietin Production by Cobaltous Chloride

Blood ◽  
1974 ◽  
Vol 44 (3) ◽  
pp. 339-346 ◽  
Author(s):  
Marilyn E. Miller ◽  
Donald Howard ◽  
Frederick Stohlman ◽  
Patricia Flanagan
Keyword(s):  
Respiratory Alkalosis ◽  
Sprague Dawley ◽  
Acid Base Balance ◽  
Acid Base ◽  
Erythropoietin Production ◽  
Sprague Dawley Rats ◽  
Base Balance ◽  
Subsequent Effect ◽  
Significant Measure ◽  
Dose Levels

Abstract Normal and nephrectomized Sprague-Dawley rats were treated with CoCl2 at three dose levels, 10, 20, and 25 µm/ 100 g body weight. The effects of this drug on acid-base balance were related to the production of erythropoietin. Within 6 hr after the administration of CoCl2 to normal rats, a dose-related respiratory alkalosis occurred associated with an increase in the affinity of hemoglobin for oxygen. This was followed by an increase in the production of erythropoietin. Nephrectomy altered the acid-base balance of the animal such that a profound acidosis occurred after the administration of CoCl2 with an associated decrease in the affinity of hemoglobin for oxygen. Erythropoietin could not be detected in these nephrectomized rats given CoCl2. These findings demonstrate that the production of erythropoietin after the administration of CoCl2 is related in significant measure to changes in acid-base balance with its subsequent effect on the affinity of hemoglobin for oxygen.

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