[Morphologic changes in the lungs of rats after death].
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Animals↗
Biomedical subjects
H Hackbarth
Publications and source records attributed to H Hackbarth.
Phase evaluation in hypothetical receivers simulating ranging in bats.
Echo delay discrimination by the bat Eptesicus fuscus had been investigated in an experiment with simulated targets jittering in range (Simmons 1979). The dip in the resulting psychometric curve was used by Simmons to suggest the neuronal implementation of a coherent cross-correlation receiver in the auditory system of bats. By computer simulation it is shown here that the dip may be even more pronounced and less susceptible to noise with alternative receiver configurations which not necessarily evaluate signal phase information coherently, e.g., a bank of neuronal filters with envelope-processing. New behavioral experiments are suggested to critically test such model hypotheses.
Acoustic Stimulation↗
Accuracy of distance measurement in the bat Eptesicus fuscus: theoretical aspects and computer simulations.
Behavioral experiments of Simmons [J. Acoust. Soc. Am. 54, 157-173 (1973) and Science 204, 1336-1338 (1979)] on the ranging accuracy in the bat Eptesicus fuscus have led to far-reaching postulates on the existence of optimal and phase-conserving processing mechanisms in the bat. In this paper, the results of computer simulations of these experiments are presented. Two receiver types are investigated: the fully coherent cross-correlation receiver and the cross-correlation receiver with envelope processing (semicoherent). It is shown that Simmons' experiments cannot be treated as a simple estimation of distance, but require at least two (range difference experiment; see Simmons, 1973) or four (range jitter experiment; see Simmons, 1979) echolocation sounds for one decision. The performance of the bat in both experiments is much worse than predicted for a coherent and a semicoherent receiver type. The bat's accuracy in Simmons' range difference experiment is at least 18 dB worse than predicted for an optimal receiver. The results of the jitter experiment cannot be interpreted in a simple way as proof that bats are able to evaluate phase information as in a fully coherent cross-correlation receiver.
Animals↗
Species and strain differences in urinary protein excretion.
The physiological excretion of urinary protein is subject to great variation influenced not only by environmental and hormonal factors but also by genetics. The present study demonstrates that there is not only variation in respect to the excretion of plasma proteins but also of other types of proteins which are specific urinary proteins. There is a close relation between body weight and total protein excretion. However, male rats and mice do not fit the allometric line calculated for the other species studied. This is of special importance since these two species are often used in kidney research. The reason for this divergence in total protein is the excretion of sex-dependent low molecular weight proteins. The excretion of albumin, which is a marker of glomerular permeability and tubular reabsorption as well, shows a marked genetic variation between different rat strains. The data presented in this study demonstrate the general admissibility of transferring data from one species to the other but also the limitations in respect especially to the sex-dependent proteins which are excreted by some species.
Analysis of Variance↗
Blood pressure in rats: a comparison of a multifactorial experimental design to measurements in an outbred stock.
Systolic blood pressure was measured in males of 8 inbred strains and 1 outbred stock of rats 5 times over a period of 20 min on 5 consecutive days. The strain means ranged between 107.9 mmHg and 149.3 mmHg. The estimated variance between strains (V = 248.7 mmHg) was about 5 times higher than the variance within strains (V = 54.3 mmHg). The intraindividual variance within strains was relatively constant (V = 24.0-37.6 mmHg), while the interindividual variance varied to a great extent (V = 4.5-44.5 mmHg) from strain to strain. The outbred stock showed values of blood pressure and components of variance similar to those of a single inbred strain. Thus, by investigation of a battery of 8 inbred strains in a multifactorial experimental design a greater phenotypic variability due to genetic strain differences is achieved than by measurements in a single outbred stock.
Analysis of Variance↗
Distribution of glomeruli in the renal cortex of Munich Wistar Frömter (MWF) rats.
The glomerular distribution in the renal cortex of the Munich Wistar Frömter (MWF) rat, a substrain of the Munich Wistar rat selected for superficial glomeruli, was compared to that of a control strain (LEW/Ztm) between 10 and 150 days of age. While there were no significant differences in body growth, kidney weight, or growth of the renal cortex in these two strains, the average diameter of Bowman's capsule and of the glomerular tuft was significantly larger (about 12%) in rats of the MWF strain which were older than 60 days. In histological sections of kidneys of MWF rats in all age groups, many glomeruli in direct contact with the renal capsule were found; thus, this developmental step must have taken place before 10 days of age. The appearance of superficial glomeruli was due to a shift of glomeruli to a position just under the renal surface, the subcapsular zone or 'cortex corticis', which is normally free of glomeruli. For the rest of the renal cortex there were only slight differences in glomerular density and in total number of glomeruli per section between these two strains. These results lead us to suppose that superficial glomeruli belong to a special nephron type; thus, these glomeruli are not enveloped by parts of the proximal tubule.
Animals↗
Strain differences in inbred rats: influence of strain and diet on haematological traits.
5 inbred strains of rats maintained on 3 commercial pelleted diets were investigated for differences in haematological traits on the 154th day of age. Number, size and haemoglobin content of the erythrocytes were shown to be strongly influenced by strain and diet. While the strain AS/Ztm was always found in a high position within the ranking order of strains, the strain DA/Ztm was always found in a low position. For nearly all haematological traits, diet II (Altromin C1000) resulted in the highest values. This was not due to a difference in the content of iron (Fe), because even though diet III (Altromin 1534) contained only 50% of the Fe in diet I (Altromin 1324), differences between these two diets were small. Significant interactions between strain and diet were shown to exist for the mean corpuscular volume (MCV) and the mean corpuscular haemoglobin (MCH). Strong genetic correlations were found between haematocrit (HCT) and haemoglobin (Hb) and between MCV and MCH, while the number of red blood cells (RBC), Hb, HCT, MCV and MCH correlated significantly within each strain. However, these environmental correlations have to be interpreted with caution, because these variables are not determined independently.
Animal Feed↗
Changes with age in renal function and morphology in C57BL/6, CBA/HT6, and B6CBAF1 mice.
Mice of the C57BL/6J and CBA/HT6J inbred strains and their F1 hybrid were investigated at 67, 202, 463, and 711 days of age to determine how genetic differences affected aging patterns of renal function and morphology. The three genotypes differed significantly in their body and kidney weights and their kidney to body weight ratios. These differences reflected functional capacities, and renal hypertrophy appeared to be an attempt to compensate for functional losses with age. The glomerular filtration rate (GFR) decreased in both inbred strains with age but remained constant in the F1 hybrid mice. There was a significant strain difference in GFR, but this difference disappeared when the GFR was considered in relation to the kidney weight. Thus the strain difference appeared to reflect differences in ability to compensate for loss of function by increasing kidney size. Osmolarities and sodium clearances decreased with age and increased with renal hypertrophy, but plasma levels were constant. Histopathological changes with age appeared to be correlated with functional changes.
Aging↗
Intraspecies allometry: correlation between kidney weight and glomerular filtration rate vs. body weight.
Allometric equations of the form of Y = a*BWb were calculated between body weight (BW) on the one hand and either kidney weight (KW) or glomerular filtration rate (GFR) on the other. By using strain and sex means obtained from 24 different inbred strains of adult mice or F1-hybrids environmental and genetical influences could be separated statistically. Thus, allometric equations reported in this study describe exclusively genetic influence. The parameters for intraspecies allometric equations obtained in these studies were compared to those in the literature presenting interspecies relationships. The double logarithmic regressions of KW vs. BW gave results different from the interspecies equation. The difference between intra- and interspecies results of allometric relationships may be due to the experimental exclusion of environmental influences. The regression parameters for GFR vs. BW obtained for the inbred strains, however, agreed very well with those of the empirical equation for interspecies relationship and also with the theoretically expected value. The dependence of GFR on BW was found to be GFR = 0.036*BW0.74 +/- 0.15, where GFR is measured in ml/min and BW in g. The exponent of 0.74 seems to be a valid biological constant that is genetically determined within and across species lines.
Animals↗
The renal clearance of albumin following intravenous loading of homologous albumin in conscious rats.
Tubular reabsorption of albumin was studied in conscious rats by measuring the renal excretion at various plasma concentrations. The plasma albumin concentration was raised by loading the animals with homologous serum albumin. By using this procedure an average plasma concentration of 54 g/l could be reached, which is about twice the physiological plasma albumin concentration in untreated rats. Throughout the experiments the glomerular filtration rate was determined by the total plasma slope clearance of 51Cr-EDTA. Following the albumin load, the 51Cr-EDTA clearance remained at 54.8 +/- 12.2 ml/min/m2 body surface. By correlating renal albumin excretion and plasma albumin concentration, the sieving coefficient of albumin, phi, of 2.35 x 10(-4), the renal albumin threshold of 38 +/- 5 g/l, and the maximal tubular transport rate of albumin of 9.6 +/- 2.6 micrograms/min/g kidney weight could be calculated (mean +/- SD). There were some variations among the animals, resulting in a fairly large standard deviation. However, these values are in agreement with recent micropuncture data.
Animals↗
Genetic analysis of renal function in mice. 2. Strain differences in clearances of sodium, potassium, osmolar and free water, and their correlations with body and kidney weight.
There was greater then 4-fold strain differences in the clearances of sodium, potassium, osmolality and free water among mice of 24 inbred strains and F1 hybrids. These differences were detectable in spite of high within-strain variations. Even under highly standardized conditions about 50% of the total variance was ascribed to the within-strain component. Males showed more significant strain differences than females, and there were more differences between strains for osmolar and free water clearances than for sodium or potassium. Most environmental correlations were not significant, while many significant genetic correlations were found between the clearances and bodyweight and, less strongly to kidney weight. Bodyweight was therefore selected as a common base, and the exponent was about 0.80 for both sodium and potassium clearance.
Animals↗
Genetic analysis of renal function in mice. 1. Glomerular filtration rate and its correlation with body and kidney weight.
Investigation of 18 inbred and 6 F1 hybrid mouse strains has shown that the glomerular filtration rate, bodyweight and kidney weight showed strain- and sex-dependent differences. Covariance analysis showed stronger correlations (genetic and environmental) between glomerular filtration rate and bodyweight than between glomerular filtration rate and kidney weight. This was predominantly due to a high within-strain variation of kidney weight (56%) in male mice. Therefore an allometric regression was calculated between the 48 strain means of glomerular filtration rate (GFR) and bodyweight (BW): GFR = 0.036 x BW0.74. Thus the term BW0.74, a suitable correction term for comparing the heat production of different species, is also suitable for the correction of glomerular filtration rate within one species.
Analysis of Variance↗
Strain differences in kidney function of inbred rats: 1. Glomerular filtration rate and renal plasma flow.
Bodyweight, kidney weight and glomerular filtration rate showed significant differences between strains--70% of the total variance was ascribed to the between-strain variance component--while the renal plasma flow showed only a slight strain difference due to a high within-strain variance component (63%). Heritability in the broad sense was 0.78 for bodyweight, 0.85 for kidney weight, 0.66 for glomerular filtration rate and 0.35 for renal plasma flow. There were significant genetic correlations between bodyweight and kidney weight (0.90), bodyweight and glomerular filtration rate (0.73), and between glomerular filtration rate and renal plasma flow (0.71), but not between kidney weight and kidney functions. Significant environmental correlations could be calculated only between bodyweight and all other variables, so that for comparison between strains it seems better to correct renal functions for bodyweight than for kidney weight, which would increase the variation of glomerular filtration rate.
Animals↗
Renal handling of albumin: clearance studies with bovine and rat serum albumin in conscious rats.
The reabsorption capacity of albumin was determined by a clearance technique following a single load of bovine or rat serum albumin in conscious rats. The maximum reabsorption capacity of both albumin amounted to 5.6--6.2 micrograms/min . 100 g BW and there seemed to be a nonselective mechanism for the two albumins. The tubular reabsorption capacity was reached at normal physiological plasma albumin concentration. The renal excretion threshold of both albumins amounted to 31.8 mg/ml, the sieving coefficient phi was calculated to be 2.0 . 10(-4). The glomerular filtration rate, controlled by the total plasma slope clearance of 51Cr-EDTA, remained unchanged following a load of rat serum albumin (54.8 +/- 12.2 ml/min . m2 body surface) but decreased significantly after the administration of bovine serum albumin.
Albuminuria↗
Proteinuria in rats in relation to age-dependent renal changes.
A variety of sex-dependent urinary proteins of low molecular weight, absent in females and in castrated males, can be identified in male rats by disc electrophoresis. In the urine of male rats of age 5.5 months, albumin comprises only 1-2% of the total protein. Albumin excretion increases greatly with age and associated kidney disease. Total protein excretion, however, stays the same or even decreases slightly as the rat ages, due to a loss of low molecular weight, sex-dependent, proteins. These are virtually absent in senescent rats (38 months of age), although total protein excretion rises tenfold in these animals due to high molecular weight plasma proteins passing into the urine; the glomerular filtration rate decreases to 70% of the value measured at 5.5 months of age.
Aging↗
[Pasteurella pneumotropica infection in a barrier-maintained rat breeding colony].
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Animals↗
Sex differences in kidney morphology and glomerular filtration rate in mice.
The relative kidney weight (1.44% greater than 1.15% greater than 1.07%) and the GFR (44 greater than 39 greater than 35 ml/min . m2) are higher in adult males than in adult females or in orchiectomized males. In contrast, GFR based on kidney weight is smallest in healthy males (1.02 less than 1.22; 1.22 ml/min . g). Only the cortex tissue seems to be increased in males, because its width (1.67 mm) is greater than in females (1.26 mm), while medullary width is identical (2.4 mm) in both sexes. Enlargement of the cortex in males can be accounted for by the nonglomerular tissue, because glomerular diameters (120 micrometers) do not differ and the number of glomeruli in representative sections is lower than in females. Cuboidal cell transformation of the outer layer of Bowman's capsule was observed in 60% of the glomeruli of the males and in 5% of the females. It might be an indicator for hyperplasie of the proximal tubular cells in the males.
Animals↗
[Determination of the mouse glomerular filtration rate by total 51Cr-EDTA plasma slope clearance depending on age and sex].
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Age Factors↗