The effects of desiccated thyroid on the rat lung

Callas, Gerald; Adkisson, V. T.

doi:10.1002/ar.1091970307

Cited by 4 publications

(6 citation statements)

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“…Hyperthyroidism can affect control of breathing through various mechanisms. These include increased metabolic demand and body temperature (37), elevated LVP (7), increased blood pressure (11), remodeling of the respiratory muscles and lungs (1,20), increased hematocrit (25), and alteration of neurotransmitter levels in brain regions involved in control of breathing (16,21,38). …”

Section: Discussionmentioning

confidence: 99%

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

Schlenker

Tamura²,

Gerdes³

2003

Journal of Applied Physiology

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der-specific effects of thyroid hormones on cardiopulmonary function in SHHF rats. J Appl Physiol 95: 2292-2298, 2003. First published August 8, 2003 10.1152/japplphysiol. 00594.2003.-Spontaneously hypertensive heart failure (SHHF) rats develop hypertension and heart failure. We hypothesized that induction of hyperthyroidism should accelerate development of heart failure in male SHHF rats. Male and female SHHF rats received diets containing desiccated thyroid glands (DTG) or a control diet for 8 wk. Male and female Wistar-Kyoto rats were used as normotensive controls. DTG treatment reduced body weight in male, but not female, SHHF rats but increased body temperature and heart weight-to-body weight ratio in both genders. In DTGtreated male SHHF rats, serum triiodothyronine levels doubled relative to SHHF controls, whereas O2 consumption increased in DTG-treated SHHF rats. Frequency of breathing in air increased in DTG-treated female rats, and ventilation increased in DTG-treated male rats. Ventilatory equivalents exhibited gender differences in SHHF rats, were decreased in both genders by DTG treatment, and reached levels similar to those of Wistar-Kyoto rats. DTG increased heart rate, right ventricular pressure, and contractility in both genders and increased left ventricular pressure in SHHF male rats. These results refute our hypothesis and suggest that cardiopulmonary function of SHHF male rats may be improved by DTG treatment.hypertension; sick euthryoid syndrome; hyperthyroidism SPONTANEOUSLY HYPERTENSIVE heart failure (SHHF) rats were originally derived from a cross between the spontaneously hypertensive rat (SHR) and the Koletsky obese rat. Subsequently, these animals were bred with SHR-N (an SHR colony at the National Institutes of Health) (27). Lean male SHHF rats die between 15 and 20 mo of age, and lean females die between 22 and 26 mo of age. Although gender differences in the development of heart failure and hypertension have been examined in this strain (11,12,18,28,36), control of breathing has not been investigated.An additional stressor on the cardiopulmonary system is thyroid hormone dysfunction. For example, hyperthyroidism increases the metabolic demands of the body and stresses the cardiovascular and respiratory systems (22,29). In contrast, patients with heart failure can actually exhibit a "sick euthryoid" syndrome, characterized by decreased or normal levels of triiodothyronine (T 3 ) and increased levels of reverse T 3 (9, 23, 35). The possibility of using thyroid hormone replacement as a therapeutic measure has been approached in patients with heart failure (13, 23). Thus, increasing thyroid levels in SHHF rats may actually improve their cardiopulmonary status.In this study, we investigated the effects of experimentally induced hyperthyroidism in male and female SHHF rats on control of breathing and cardiac function. Gender-matched Wistar-Kyoto (WKY) rats were used as normotensive, euthryoid controls. We hypothesized that the combined effects of hyperthyroidism and hypertension would ...

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Section: Discussionmentioning

confidence: 99%

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

Schlenker

Tamura²,

Gerdes³

2003

Journal of Applied Physiology

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“…The size of individual gas-exchange units is inversely proportional to the species mass-specific Vo2; this allows species with a high mass-specific Vo2 to achieve sufficient Sa to meet the intensity of their metabolic needs without having a lung volume disproportionately large compared to its body mass (1). Interestingly, although the lung has sufficient Sa to sustain a short-term 10-fold increase in Vo2, as might occur with exercise (3), it responds to smaller but more prolonged (weeks to months) elevations of VO2 by increasing its gas-exchange capacity as reflected in its Sa (4)(5)(6)(7).…”

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confidence: 99%

Sexual dimorphism in the architecture of the lung's gas-exchange region.

Massaro

Mortola

Massaro

1995

Proc. Natl. Acad. Sci. U.S.A.

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The lung's only vital function is to provide sufficient gas-exchange surface area (Sa) to meet the organism's needs for oxygen uptake (Vo2) and carbon dioxide elimination. A direct linear relation between Sa and Vo2 and an inverse linear relation between the size of the lung's gas-exchange units and the species mass-specific Vo2 are strongly conserved across species. Within species, Sa increases in response to prolonged (weeks) elevation of Vo2. We now report sex-dependent deviations from these relationships that seem to anticipate the need for increased gas-exchange capacity engendered in females by the metabolic demands of pregnancy and lactation. We found that although V02 almost doubled in rats during pregnancy and lactation, Sa was the same in age-matched virgin, pregnant, and lactating females. However, at the onset of sexual maturity, virgin female rats and mice had higher mass-specific Sa than males of the same species although mass-specific Vo2 was identical, within species, in both sexes. In addition, even though mass-specific Vo2 was identical in males and females, alveoli were 30% and 50%o smaller in female rats and mice, respectively, than males of the same species. We suggest the greater mass-specific Sa and smaller alveoli in females in spite of identical mass-specific Vo2 as males were selected for evolutionarily; they help females meet the metabolic demands of reproduction without adding to the energy demands of these periods a requirement to form additional lung. The lung's only known vital function is to provide sufficient gas-exchange surface to meet the organism's needs for oxygen uptake and carbon dioxide elimination. The importance of the relationship between oxygen consumption (VO2) and the size of the lung's gas-exchange surface area (Sa) can be appreciated from the strong interspecific conservation of a direct linear relation between Vo2 and Sa (1, 2). The size of individual gas-exchange units is inversely proportional to the species mass-specific Vo2; this allows species with a high mass-specific Vo2 to achieve sufficient Sa to meet the intensity of their metabolic needs without having a lung volume disproportionately large compared to its body mass (1). Interestingly, although the lung has sufficient Sa to sustain a short-term 10-fold increase in Vo2, as might occur with exercise (3), it responds to smaller but more prolonged (weeks to months) elevations of VO2 by increasing its gas-exchange capacity as reflected in its Sa (4-7).Pregnancy and lactation constitute long periods during which Vo2 is moderately elevated (8). Because these periods are recurrent, and rapidly so in many species, the high metabolic rate associated with reproduction may represent the "steady-state" condition during much of a female's reproductive life. The intestine adapts to reproduction-associated increased energy needs with elevations of mass and absorptive surface capacity that regress when lactation ends (9). This increased capacity occurs even though the intestine's absorptive capacity in nonpregn...

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“…However, physiological and morphometric data indicate a structural change. The results of an earlier study performed in our laboratory (Callas and Adkisson, 1980) showed that the lung volume in thyroid-treated rats (adrenals intact) was 35% greater than their littermate controls. In that study, air and saline pressure-volume curves were done.…”

Section: Discussionmentioning

confidence: 78%

“…Administration of thyroid hormone has been reported to result in an increase in the number and size of lung lamellar bodies in fetal (Wu et al, 1973;Hitchcock, 1979) and mature animals (Douglas et al, 1970;Redding et al, 1972), and an increase in lung compliance and lung volume (Callas, 1978; Thompson, 1979; Callas and Adkisson, 1980) in mature animals. Similar effects have been reported following the administration of adrenal hormones (DeLemos et al, 1970;Kotas and Avery, 1971; Picken et al, 1974).…”

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confidence: 99%

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Morphometric changes in the lungs of rats following adrenalectomy supplemented by desiccated thyroid

Adkisson¹,

Callas²

1982

Anat. Rec.

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Studies were conducted to assess the effects of thyrotoxicosis on the lung of the adult adrenalectomized rat. The animals were divided into four groups of seven animals each: Adrenalectomized animals receiving desiccated thyroid in their food for 8 weeks, adrenalectomized animals, and sham-operated animals receiving regular laboratory chow. Unoperated animals were used as controls. There were no differences in the pressure-volume curves or morphometric parameters between unoperated-control and sham-operated animals; therefore they will be collectively reported as control animals. Lung volume in the thyroidtreated animals showed an increase of 19% in pressure-volume studies when compared with the other groups. Lung volume determined morphometrically demonstrated a 19% increase in volume when adrenalectomized thyroid-treated rats were compared with control animals, and a 29% increase compared with adrenalectomized animals. The thyroid-treated animals also showed an alveolar surface density (SJ increase of 58% over control and 28% over adrenalectomized animals. In addition, alveolar surface area (S,) of the treated animals was 89% greater than control and 65% greater than adrenalectomized animals. The marked difference in the surface-to-volume ratio indicates that alveoli were smaller and more numerous in the lungs from the thyroid-treated animals. These results are readily apparent in examination of light microscopic sections of the lung specimens from the four groups of animals. These findings indicate that chronic thyroid administration results in a significant increase in lung volume, which we attribute to increased alveolar partitioning.

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The effects of desiccated thyroid on the rat lung

Cited by 4 publications

References 8 publications

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

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

Sexual dimorphism in the architecture of the lung's gas-exchange region.

Morphometric changes in the lungs of rats following adrenalectomy supplemented by desiccated thyroid

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