Gender-specific effects of thyroid hormones on cardiopulmonary function in SHHF rats

Schlenker, Evelyn H.; Tamura, Toyoyuki; Gerdes, A. Martin

doi:10.1152/japplphysiol.00594.2003

Cited by 9 publications

(5 citation statements)

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“…Longitudinal studies indicated that mutant mice homozygote (ob/ob) for the obesity gene also developed rapid baseline breathing relative to wild-type mice (31,35,46). Further evidence for obesity, and not predominantly hypertension, contributing to the higher f and lower VT pattern in DI-treated obese SHHF rats in the present study comes from a recent study of lean SHHF rats (40). Male lean SHHF in that study exhibited hypertension and had a f of 111 Ϯ 3 breaths/ min relative to 115 Ϯ 2 breaths/min in Wistar-Kyoto normotensive control rats.…”

Section: Discussionsupporting

confidence: 51%

“…After the rat became accustomed to his surroundings and frequency of breathing (f; breaths/min) stabilized, ventilation was evaluated using the barometric method used frequently in our laboratory (40). The Bio-Pac acquisition computer system was used to record the breathing pattern of each rat to determine f and tidal volume (VT) and calculate minute ventilation (V E), the product of the two previous variables.…”

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confidence: 99%

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Effects of long-term captopril andl-arginine treatment on ventilation and blood pressure in obese male SHHF rats

Schlenker

Kost

Likness

2004

Journal of Applied Physiology

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Schlenker, E. H., C. K. Kost, Jr., and M. M. Likness. Effects of long-term captopril and L-arginine treatment on ventilation and blood pressure in obese male SHHF rats. J Appl Physiol 97: 1032-1039, 2004. First published May 14, 2004 10.1152/japplphysiol.00255.2004We investigated the effects of captopril (Cap) and L-arginine (Arg) on hypertension and cardiopulmonary function. Our hypothesis was that Cap therapy or Arg will improve cardiopulmonary risk factors for hypertension and hypoventilation in the obese spontaneously hypertensive heart failure rat, which is characterized by hypertension, obesity, and disorders of lipid and carbohydrate metabolism. For the first study, one group of rats received Cap in drinking water, and a second group received deionized water (DI). For the second study, rats were further subdivided. Some Cap-treated rats continued on this treatment, and the other half were now given DI to determine whether there would be residual effects of Cap treatment. A subgroup of rats who had received DI was then given Arg, whereas the rest remained on DI. In the first study, Cap-treated rats exhibited decreases in systolic and diastolic blood pressures, frequency of breathing, and minute ventilation, but ventilatory control was maintained. In contrast, blood pressures and relative ventilation to metabolism were higher in the DI-treated group. Removal of Cap increased blood pressure and decreased tidal volume while these rats maintained frequency. Although Arg-treated rats did not exhibit a decrease of blood pressure, ventilation was maintained in this group by preserving tidal volume. Thus Cap and Arg affected ventilation through different mechanisms independent of blood pressure.spontaneously hypertensive heart failure rat; hypertension; metabolic syndrome X; ventilatory equivalent; frequency OBESITY, DIABETES, AND HYPERTENSION are major risk factors for cardiopulmonary and renal disease (1,7,9,18,41). The concurrence of these risk factors is also known as the metabolic syndrome X (8, 49). In addition to metabolic and cardiovascular complications, individuals with metabolic syndrome X can also present with hypoventilation during sleep and obstructive sleep apnea (8, 47).Hypertension and congestive heart failure originate from the activation of multiple neuroendocrine systems, including the renin-angiotensin (Ang), endothelin, and atrial natriuretic peptide systems (13, 23-25, 41, 51). One in four adults develops hypertension and is at increased risk of stroke, coronary disease, congestive heart failure, and end-stage renal disease (2). Ang-converting enzyme (ACE) inhibitors are regarded as the first line of hypertensive therapy in diabetic patients due to their protective effects on the cardiovascular and renal systems (23,27,45). Ideally, treatment of hypertension would normalize blood pressure early in the disease, thus decreasing the incidence of cardiovascular-associated morbidity and mortality. Another agent that has been shown to decrease blood pressure is L-arginine (Arg) (50), a substrate ...

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Section: Discussionsupporting

confidence: 51%

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confidence: 99%

Effects of long-term captopril andl-arginine treatment on ventilation and blood pressure in obese male SHHF rats

Schlenker

Kost

Likness

2004

Journal of Applied Physiology

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“…Hamsters were placed into a cylindrical Plexiglas chamber for measurement of oxygen consumption as described previously (28). Oxygen consumption was corrected to STPD values and divided by body weight.…”

Section: Methodsmentioning

confidence: 99%

Treatment of subclinical hypothyroidism reverses ischemia and prevents myocyte loss and progressive LV dysfunction in hamsters with dilated cardiomyopathy

Khalife

Tang

Kuzman

et al. 2005

American Journal of Physiology-Heart and Circulatory Physiology

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. Treatment of subclinical hypothyroidism reverses ischemia and prevents myocyte loss and progressive LV dysfunction in hamsters with dilated cardiomyopathy. Am J Physiol Heart Circ Physiol 289: H2409 -H2415, 2005. First published July 15, 2005; doi:10.1152/ajpheart.00483.2005.-Growing evidence suggests that thyroid dysfunction may contribute to progression of cardiac disease to heart failure. We investigated the effects of a therapeutic dose of thyroid hormones (TH) on cardiomyopathic (CM) hamsters from 4 to 6 mo of age. CM hamsters had subclinical hypothyroidism (normal thyroxine, elevated TSH). Left ventricular (LV) function was determined by echocardiography and hemodynamics. Whole tissue pathology and isolated myocyte size and number were assessed. TH treatment prevented the decline in heart rate and rate of LV pressure increase and improved LV ejection fraction. The percentage of fibrosis/necrosis in untreated 4-mo-old CM (4CM; 15.5 Ϯ 2.2%) and 6-mo-old CM (6CM; 21.5 Ϯ 2.4%) hamsters was pronounced and was reversed in treated CM (TCM; 11.9 Ϯ 0.9%) hamsters. Total ventricular myocyte number was the same between 4-and 6-mo-old controls but was reduced by 30% in 4CM and 43% in 6CM hamsters. TH treatment completely prevented further loss of myocytes in TCM hamsters. Compared with agematched controls, resting and maximum coronary blood flow was impaired in 4CM and 6CM hamsters. Blood flow was completely normalized by TH treatment. We conclude that TH treatment of CM hamsters with subclinical hypothyroidism normalized impaired coronary blood flow, which prevented the decline in LV function and loss of myocytes. thyroid hormones; remodeling; fibrosis; blood flow THE EFFECTS OF THYROID HORMONES (TH) on the cardiovascular system have been well studied. It is clear that both hypothyroidism and hyperthyroidism can lead to deleterious changes in cardiovascular function. Decreased TH levels have been reported in a variety of nonthyroidal illnesses (18), including congestive heart failure (12) and myocardial infarction (6). The decrease in TH levels also appears to be related to the severity of heart failure (12). This is not a minor point, because low 3,5,3'-triiodothyronine (T 3 ) concentrations are a strong, independent predictive marker of poor prognosis in cardiac patients and might represent a determining factor directly implicated in the evolution and prognosis of these conditions (14). Growing evidence also suggests that subclinical thyroid dysfunction might play an important role in heart failure (10, 21). This is highly relevant from a clinical standpoint because this patient group does not typically receive TH treatment.Development of heart failure is accompanied by a variety of neuroendocrine changes. Cardiac failure was shown to be associated with both a decline in circulating TH levels (11,17) and altered cardiac TH signaling, as evidenced by changes in myocardial expression of TH nuclear receptor isoforms (15,16). The observation that short-term TH administration improves cardiac performance, both in anim...

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“…Studies that investigated the interaction between hypertension, gender and respiratory control have mainly focused on sleep apnea syndrome (7), and male gender and hypertension have been suggested to be risks for human sleep apnea (8). Animal models have been useful to investigate the relationship between hypertension and abnormal control of breathing (9). Despite recent literature reviews focusing on the relationship between breathing and hypertension (10,11), a possible relationship between hypertension and abnormal ventilatory control was never examined before in spontaneously hypertensive rats (SHR), an outstanding hypertensive model.…”

Section: Introductionmentioning

confidence: 99%

Morphometric analysis of the phrenic nerve in male and female Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR)

Rodrigues

Ferreira

Salgado

et al. 2011

Braz J Med Biol Res

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Gender-specific effects of thyroid hormones on cardiopulmonary function in SHHF rats

Cited by 9 publications

References 35 publications

Effects of long-term captopril andl-arginine treatment on ventilation and blood pressure in obese male SHHF rats

Effects of long-term captopril andl-arginine treatment on ventilation and blood pressure in obese male SHHF rats

Treatment of subclinical hypothyroidism reverses ischemia and prevents myocyte loss and progressive LV dysfunction in hamsters with dilated cardiomyopathy

Morphometric analysis of the phrenic nerve in male and female Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR)

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