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Biomedical subjects

R Behm

Publications and source records attributed to R Behm.

26 records · Page 2Linked to original sources
PubMed1987

The carotid bodies of renal hypertensive rats.

The carotid bodies of renal hypertensive rats (one kidney wrap model) were studied by light-microscopic and morphometric methods. Rats with established hypertension showed massive intraglomic vascular alterations, such as exudation of plasma, subendothelial fibrinoid deposits and fibrinoid necroses of the intima and media. Additionally a granuloma-like perivascular proliferation of fibroblasts and histiocytes was seen. The total carotid body volume was enlarged but the volume of the specific glomic tissue was reduced in comparison with normotensive controls. In rats with borderline hypertension similar pathological changes were found but in a more reduced extension. Additionally in these rats some intraglomic vessels showed an accumulation of acid mucopolysaccharides and an hyperplasia of mediocytes. Rats with such vessel alterations also exhibited a small enlargement of specific glomic tissue. In general the pathological changes of the carotid bodies in renal hypertensive rats are different in comparison with those in the glomera carotici of rats with spontaneous hypertension (SHR, GH rats). This study suggests that an elevated blood pressure does not solely cause an increment of the specific chemoreceptive tissue mass of the carotid bodies.

Animals↗
PubMed1986

Carotid body volumes of spontaneously hypertensive rats (SHR) growing up in hypobaric hypoxia.

Chronically hypoxic spontaneously hypertensive rats (SHR) developed 4-5 times bigger carotid bodies in relation to age-matched normoxic control SHR. When compared with the effects of chronic hypoxic hypoxia the influences of different levels of the systemic arterial blood pressure on carotid body volume were rather small. The data indicate that the carotid bodies of young SHR react to chronic arterial hypoxia in the same way as the glomera carotici of normotensive Wistar rats.

Altitude↗
PubMed1986

Blood pressure adjustment, left ventricular weight and carotid body size in young spontaneously hypertensive rats growing up in hypoxia.

Spontaneously hypertensive rats (SHR) of the Okamoto-Aoki strain grew up in low pressure chambers at a simulated altitude of 4000 m from their 5th to their 18th week of age. Both the sea-level control rats and the hypoxic rats were divided into groups with and without additional hypertonic salt solution. Due to chronic hypoxia the development of systemic hypertension and the left ventricular hypertrophy were diminished in young SHR. In contrast to adult SHR, these effects were attenuated but not abolished by addition of salt. Independently of the salt availability, exposure to long-lasting hypoxia increases the carotid body volume significantly. The data indicate that chronic hypoxia has a stronger effect on carotid body enlargement than different levels of the systemic arterial blood pressure.

Animals↗
PubMed1984

Sustained suppression of voluntary sodium intake of spontaneously hypertensive rats (SHR) in hypobaric hypoxia.

Spontaneously hypertensive rats (SHR) of the Okamoto-Aoki-strain (n = 20) and normotensive rats (NCR) of a random-bred Wistar strain (n = 20) were kept in low-pressure chambers for 13 days at sea-level atmospheric pressure, then for 20 days at a simulated altitude of 4000 m, and subsequently again for 10 days at sea-level. The unrestrained animals were placed singly in metabolic cages and had free access to food, water, and a 2.5% NaC1-solution. Exposure to hypobaric hypoxia led to a transient decrease of daily food and water intake in both strains of animals and a slight reduction of saline consumption in the NCR. In contrast, the SHR showed a massive and sustained suppression of their voluntary intake of hypertonic saline throughout high-altitude exposure. Renal electrolyte and water excretion followed the reactions of salt and water intake. - In an additional series of experiments it was found that SH-rats react with a decrease of their systemic arterial blood pressures in hypobaric hypoxia only on condition that food and water but no additional salt is available to the animals. The data suggest that the antihypertensive effects of chronic high-altitude hypoxia depend both on the availability of salt and a reduction of salt appetite.

Altitude↗
PubMed1984

Influence of age on carotid body size and arterial chemoreceptor reflex effects in spontaneously hypertensive (SHR) and normotensive rats.

In normotensive Wistar rats of a random-bred strain and in spontaneously hypertensive rats (SHR) of the Okamoto-Aoki-strain, the mean systemic arterial blood pressure, the pO2, pCO2, pH-values and the base excess of the arterial blood were measured during ventilating normal air as well as hypoxic (12.6% O2 in N2) and hyperoxic (100% O2) gas mixtures. The animals were anaesthetized and breathed spontaneously; they aged 5-6, 15-20, 30-40, and 50-70 weeks. The volume of their carotid bodies was determined morphometrically. When compared with the age-matched normotensive controls at an age of 5-6 weeks the SHR already exhibited slightly but significantly elevated blood pressures but had equal carotid body size and arterial carbon dioxide tension. In contrast, hypertensive animals in the established phase of hypertension (older than 15 weeks) showed greater carotid bodies and a highly significant respiratory alkalosis when compared with the corresponding age-group of the normotensive rats. The reactions of the mean systemic arterial blood pressure and the arterial pCO2 provoked by hypoxia and hyperoxia proved to be age-dependent in both the normotensive and hypertensive animals but this influence of age was different in the two strains of rats. The data support the concept that alterations of arterial chemoreceptor structures and reflex effects found in the established phase of hypertension are the result of this disease. Furthermore they indicate that, when interpreting arterial chemoreceptor reflex effects in hypertensive humans and animals, the stage of hypertension must be taken into account.

Aging↗
PubMed1978

[Performance dependent lysine requirement of fattening pigs. 3. Effect of amino acid and energy intake on fat, protein and lysine deposition of swine].

The gain in structural matter had a linear course with a corresponding feeding intensity and depending on the period of fattening. However, the animals given high-energy diets deposited 130 g protein per day during the first fattening period, this deposition being compensated in the course of further growth by a considerably lower deposition in the sense of aequifinality. Up to a live weight of 70 kg, animals subjected first to restricted feeding and then to fully balanced feeding revealed the highest protein deposition during the last period of fattening, this fact emphasizing the leanmeat character of the animal material used. The daily fat deposition was found clearly determined by energy intake and independent of amino acid supply. Lysine conversion was influenced by the intake of lysine and energy. Under feeding to norm it reached some 40 and 30% during the first and second periods of fattening, respectively.

Adipose Tissue↗
PubMed1978

[Performance-related lysine requirement of fattening pigs. 4. Effect of energy and amino acid intakes on composition of gain and derivation of lysine requirement].

The results show that protein and fat syntheses proceed simultaneously in growing swine. Reducing the energy intake during the 2nd half of the fattening period in pigs of modern genetic construction (hybrid pig) is likely to cut both fat and protein deposition per day. This will result in lower daily gains, a longer fattening period and higher energy expenditure. Therfore, it is not advisable to restrict energy supply during the 2nd half of fattening of pigs derived from modern breeding lines. The optimum amino acid : energy ratio allows to make full use of the protein deposition capacity in pigs with prefixed slaughter weight. For the limiting amino acid lysine it was found to be 10.5 g/1,000 energetic feed equivalents (swine) or 3 g/Mcal NEF (swine), and, taking into account amino acid digestibility, 9.5 g dig. lysin/1,000 energetic feed equivalents (swine) and 2.7 g dig. lysin/Mcal NEF (swine), respectively.

Animals↗