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Title: Hypertension during chronic exposure to cold: Comparison between Sprague Dawley (SD) and Long Evans (LE) strains

Abstract

Hypertension accompanies chronic exposure of SD rats to cold (5-6C), including elevation of systolic, diastolic, and mean blood pressures and cardiac hypertrophy. The renin-angiotensin system may play an important role. Earlier studies suggested that the LE strain may have a decrease in angiotensin I converting enzyme (ACE) activity. Measurement of ACE activity in plasmas of SE and LE strains revealed that basal activity of ACE in the plasma of the LE strain was significantly less than that of the SD strain. A second study was carried out in which both strains were exposed to cold for 7 weeks. There were clear differences between strains. Rats of the SD strain had a significant elevation in their blood pressure; a significantly increased urinary output of norepinephrine (NE) and epinephrine (E); and significant increases in weights of heart, kidneys, adrenals, and brown adipose tissue (IBAT) compared to their controls maintained at 26C. In contrast, rats of the LE strain were less responsive to cold in that blood pressure failed to rise as sharply and to attain as high a level; NE and E outputs, as well as weights of heart and IBAT were significantly less than those of rats of the cold-treated SDmore » strain. Thus, the lower ACE activity in plasma of LE strain, as well as a reduced secretion of catecholamines, may protect these rats against the rise of blood pressure characteristically observed when rats of the SD strain are exposed to cold.« less

Authors:
; ;  [1]
  1. (Univ. of Florida, Gainesville (United States))
Publication Date:
OSTI Identifier:
5374753
Alternate Identifier(s):
OSTI ID: 5374753
Report Number(s):
CONF-9104107--
Journal ID: ISSN 0892-6638; CODEN: FAJOE
Resource Type:
Conference
Resource Relation:
Journal Name: FASEB Journal (Federation of American Societies for Experimental Biology); (United States); Journal Volume: 5:4; Conference: 75. annual meeting of the Federation of American Societies for Experimental Biology (FASEB), Atlanta, GA (United States), 21-25 Apr 1991
Country of Publication:
United States
Language:
English
Subject:
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.; HYPERTENSION; PATHOGENESIS; HYPOTHERMIA; BIOLOGICAL EFFECTS; PEPTIDE HYDROLASES; ENZYME ACTIVITY; RATS; BLOOD PRESSURE; ADRENALINE; CATECHOLAMINES; CHRONIC EXPOSURE; GENETIC VARIABILITY; NORADRENALINE; RENIN; TEMPERATURE EFFECTS; ADRENAL HORMONES; AMINES; ANIMALS; AROMATICS; AUTONOMIC NERVOUS SYSTEM AGENTS; BIOLOGICAL VARIABILITY; BODY TEMPERATURE; CARDIOTONICS; CARDIOVASCULAR AGENTS; CARDIOVASCULAR DISEASES; DISEASES; DRUGS; ENZYMES; HORMONES; HYDROLASES; HYDROXY COMPOUNDS; MAMMALS; NEUROREGULATORS; NONSPECIFIC PEPTIDASES; ORGANIC COMPOUNDS; PHENOLS; POLYPHENOLS; PROTEINS; RODENTS; SYMPATHOMIMETICS; SYMPTOMS; VASCULAR DISEASES; VERTEBRATES 560200* -- Thermal Effects

Citation Formats

Riesselmann, A., Baron, A., and Fregly, M.J.. Hypertension during chronic exposure to cold: Comparison between Sprague Dawley (SD) and Long Evans (LE) strains. United States: N. p., 1991. Web.
Riesselmann, A., Baron, A., & Fregly, M.J.. Hypertension during chronic exposure to cold: Comparison between Sprague Dawley (SD) and Long Evans (LE) strains. United States.
Riesselmann, A., Baron, A., and Fregly, M.J.. Mon . "Hypertension during chronic exposure to cold: Comparison between Sprague Dawley (SD) and Long Evans (LE) strains". United States. doi:.
@article{osti_5374753,
title = {Hypertension during chronic exposure to cold: Comparison between Sprague Dawley (SD) and Long Evans (LE) strains},
author = {Riesselmann, A. and Baron, A. and Fregly, M.J.},
abstractNote = {Hypertension accompanies chronic exposure of SD rats to cold (5-6C), including elevation of systolic, diastolic, and mean blood pressures and cardiac hypertrophy. The renin-angiotensin system may play an important role. Earlier studies suggested that the LE strain may have a decrease in angiotensin I converting enzyme (ACE) activity. Measurement of ACE activity in plasmas of SE and LE strains revealed that basal activity of ACE in the plasma of the LE strain was significantly less than that of the SD strain. A second study was carried out in which both strains were exposed to cold for 7 weeks. There were clear differences between strains. Rats of the SD strain had a significant elevation in their blood pressure; a significantly increased urinary output of norepinephrine (NE) and epinephrine (E); and significant increases in weights of heart, kidneys, adrenals, and brown adipose tissue (IBAT) compared to their controls maintained at 26C. In contrast, rats of the LE strain were less responsive to cold in that blood pressure failed to rise as sharply and to attain as high a level; NE and E outputs, as well as weights of heart and IBAT were significantly less than those of rats of the cold-treated SD strain. Thus, the lower ACE activity in plasma of LE strain, as well as a reduced secretion of catecholamines, may protect these rats against the rise of blood pressure characteristically observed when rats of the SD strain are exposed to cold.},
doi = {},
journal = {FASEB Journal (Federation of American Societies for Experimental Biology); (United States)},
number = ,
volume = 5:4,
place = {United States},
year = {Mon Mar 11 00:00:00 EST 1991},
month = {Mon Mar 11 00:00:00 EST 1991}
}

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  • Rats frequently develop various tumors, many of them malignant; the majority of tumors in the females develop in the mammary glands. In primary spontaneous tumors and lymphomas virus particles cannot be found on electron microscopic examination; transmission of the tumors by filtered extracts has not been successful. In our colonies of Sprague-Dawley rats the incidence of tumors was 22% in females and 5% in males; in Long-Evans rats the incidence of tumors was 28% in females and 10% in males. In (Sprague-Dawley x Long-Evans) F/sub 1/ hybrids the incidence of tumors was 67% in females and 32% in males, aboutmore » twice as high as in the parental strains. Fractionated total-body x-irradiation (150 rads five times at weeky intervals) (1 rad = 0.01 gray) increased the incidence of tumors in Sprague-Dawley rats from 22 to 93% in females and from 5 to 59% in males. In Long-Evans rats, irradiation increased the incidence of tumors from 28 to 63% in females and from 10 to 42% in males. The incidence of malignant tumors was almost twice as high in irradiated Sprague-Dawley and Long-Evans rats as compared with nonirradiated animals of the same strains. Partial shielding during irradiation had no significant effect on the incidence or on the forms of tumors developing in the irradiated animals. In striking contrast to results of experiments carried out on mice, the incidence of leukemia and lymphomas was not increased in the irradiated rats, as compared with control animals.« less
  • Mature female Sprague-Dawley (SD) and Long-Evans (LE) rats were ovariectomized (OVX), and given a single sc injection of either 25 or 100 ..mu..g polyestradiol phosphate (PEP); seven days later blood samples were withdrawn at two hour intervals from 1100 to 2100 hours to detect the presence of an afternoon surge of prolactin (PRL). Other groups of OVX rats of both strains also treated with PEP were sampled before and at 2, 5, 10 and 30 min after iv administration of 1 ..mu..g synthetic thyrotropin releasing hormone (TRH). Pituitary (AP) and uterine weights were determined following sacrifice one day after TRHmore » treatment. The AP homogenates and plasma samples were assayed for PRL by radioimmunoassay. Rats of both strains had afternoon PRL surges and in both strains the magnitude and/or duration of the surges were enhanced by the higher dose of PEP. However, within each PEP dose LE rats released significantly more PRL during the surge than did SD drats. Rats of both strains also rleased PRL in response to TRH and this response was enhanced in both strains by the higher of the two doses of PEP. These data not only show that strain differences exist in estrogen-induced or mediated PRL release in the rat but also indicate that the differences are not uniform.« less
  • Previous reports have demonstrated that cadmium- induced testicular necrosis is an age-dependent process. However, little information exists on age-related intestitial cell (IC) damage in the rat after acute exposure to Cd. In-vitro and in-vivo measures of testicular damage were utilized to compare the sensitivity of these measures and to further investigate age-related Cd-induced testicular damage. Testes, epididymides, and seminal-vesicle weights, serum testosterone (sT), hCG-stimulated sT, and basal and stimulated IC testosterone (T) production were compared in rats 21 d following an injection of 2 mg Cd/kg at 9, 37, 67, and 97 d of age. The only Cd-related change notedmore » for immature rats was an 84% reduction in sT. In rats injected when 37 d old, hCG-stimulated sT and epididymides and seminal-vesicle weights, although depressed, were not significantly altered. However, all other measurements were significantly depressed. All measures of testicular damage were significantly depressed in rats injected at 67 and 97 d of age. Overall, in vitro measures were more sensitive indicators of Cd-induced testicular damage than in vivo measures.« less
  • Previous reports have demonstrated that cadmium- (Cd-) induced testicular necrosis is an age-dependent process. However, little information exists on age-related intestitial cell (IC) damage in the rat after acute exposure to Cd. In this study in vitro and in vivo measures of testicular damage were utilized to compare the sensitivity of these measures and to further investigate age-related Cd-induced testicular damage. Testes, epididymides, and seminal vesicle weights, serum testosterone (sT), hCG-stimulated sT, and basal and stimulated IC testosterone (T) production were production were compared in rats 21 d following an injection of 2 mg Cd/kg at 9, 37, 67, andmore » 97 d of age. The only Cd-related change noted for immature rats was an 84% reduction in sT. In rats injected when 37 d old, hCG-stimulated sT and epididymides and seminal vesicle weights, although depressed, were not significantly altered. However, all other measurements were significantly depressed. All measures of testicular damage were significantly depressed in rats injected at 67 and 97 d of age. Overall, in vitro measures were more sensitive indicators of Cd-induced testicular damage than in vivo measures. However, sT and hCG-stimulated sT appeared to be useful indicators of Cd effects on the pituitary-gonadal axis. ICs from immature rats (9 d old) were unaffected by Cd exposure, while stimulated T reproduction in ICs from 37-, 67-, and 97-d-old animals was reduced at least 50%. The severity of Cd-induced testicular damage increases with age for all variables measured.« less