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Rahlmann, D. F.

Publications and source records attributed to Rahlmann, D. F..

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1985

Skeletal mass change as a function of gravitational loading

The hypothesis that increased loading on an animal by chronic centrifugation results in an increase in skeletal mass was tested, using metabolically mature hamsters, rats, guinea pigs, Dutch rabbits and New Zealand rabbits representing a body mass range from 0.15 to 3.8 kg. Groups of 12 male animals of each species were subjeted to 2.0 g for 6 weeks on a 2.74 radius centrifuge with one degree of freedom. Subsequently, six of the animals were killed to measure whole body composition, while the rest comprised the control group, recovering for four weeks at 1.0 g prior to composition analysis. Results show a significant increase in bone mineral mass at 2.0 g. These centrifuge experiment results were then compared with the results of the USSR Cosmos Biosatellite experiment, whereby five rats experienced osteoporosis after 18.5 days of weightlessness. The opposing nature of effects that occurred at 0 g and 2.0 g is indicated schematically of particular interest is the fact that the bone mineral mass of the Cosmos 1129 flight rats was 17 pct less than that of the 1.0 g controls; whereas the bone mineral mass of the centrifuge rats was 18 pct greater than that of their 1.0 g controls. It is concluded that the bone mineral mass of the rat is directly proportional to gravitational loading over the range of 0 g to 2.0 g.

Pace, N.↗
NASA NTRS1984

Muscularity as a function of species, sex and age in small mammals

Changes in the body skeletal muscle mass SMM (measured as a function of the ratio between the body creatine mass and the fat-free muscle creatine), and in muscularity (expressed as the ratio of SMM to fat-free body mass) were studied as functions of age, sex, and species in mouse, rat, hamster, guinea pig, and rabbit. Six animals of each sex were examined in eight age cohorts ranging from 1 to 24 months. Both species and age factors affect SMM. Strong sexual dimorphism in the SMM changes with age was displayed by mouse, rat, and guinea pig, whereas the hamster and rabbit were statistically monomorphic. The mouse, rat, and hamster attain a maximal SMM at about 1 year of age, whereas in the guinea pig and rabbit the decrease in SMM starts after 2 years. The value of muscularity reached a peak at age of 2-3 months in all animals of both sexes, with a pronounced difference among the species. The mouse emerged as the most muscular, while the guinea pig the least muscular, of all species.

Pace, N.↗
NASA NTRS1983

Thermoneutral zone and scaling of metabolic rate on body mass in small mammals

A 4-species animal model suitable for experimental study of the effect of change in gravitational loading on the scale relationship between metabolic rate and total body mass is used to study the effect of temperature on metabolic rate in six male animals, 8-10 months of age, of each of the four species in the ambient temperature range 20-36 C. The measurements taken permitted partitioning of total body heat output into sensible heat loss by radiation, conduction and convection, and into latent heat loss by evaporation of water from the body surface. It is shown that the condition of thermoneutrality is important for metabolic scale effect studies, and that the thermoneutral zone for the species considered here is a narrow one.

Pace, N.↗
NASA NTRS1983

Effects of weightlessness on body composition in the rat

The effects of weightlessness on the body composition of rats were investigated using 5 male rats exposed to 18.5 days of weightlessness on the COSMOS 1129 biosatellite and killed after reentry. The animals were immediately dissected and the three major body divisions (musculoskeletal system, skin, and pooled viscera) were analyzed for fat, water, solids, and six elements. These results were determined as percentages of the fat-free body or its components and then compared with two groups of terrestrial controls, one of which was subjected to a flight simulation in a spacecraft mock-up while the other was under standard vivarium conditions. Compared with the control groups, the flight group was found to exhibit a reduced fraction of total body water, a net shift of body water from skin to viscera, a marked diminution in the fraction of extracellular water in the fat-free body, a marked reduction in the fraction of bone mineral, no change in the quantity of stored fat or adrenal masses, and a net increase in total muscle mass as indicated by total body creatine, protein, and body cell mass.

Pitts, G. C.↗
NASA NTRS1982

Estimation of skeletal muscle mass from body creatine content

Procedures have been developed for studying the effect of changes in gravitational loading on skeletal muscle mass through measurements of the body creatine content. These procedures were developed for studies of gravitational scale effects in a four-species model, comprising the hamster, rat, guinea pig, and rabbit, which provides a sufficient range of body size for assessment of allometric parameters. Since intracellular muscle creatine concentration varies among species, and with age within a given species, the concentration values for metabolically mature individuals of these four species were established. The creatine content of the carcass, skin, viscera, smooth muscle, and skeletal muscle was determined for each species. In addition, the skeletal muscle mass of the major body components was determined, as well as the total and fat-free masses of the body and carcass, and the percent skeletal muscle in each. It is concluded that these procedures are particularly useful for studying the effect of gravitational loading on the skeletal muscle content of the animal carcass, which is the principal weight-bearing organ of the body.

Pace, N.↗
NASA NTRS1982

Cardiovascular responses of the chronically instrumented monkey during simulated space flight

A pod enclosure system designed by the Environmental Physiology Laboratory at the University of California at Berkeley is found to be eminently suitable for work with monkeys. The pattern of cardiovascular activity is found to vary. In the first half of the exposure, the hourly mean values suggest an initial period of instability, most marked for heart rate, beginning at 'launch.' In the second half of the exposure, the final three days, the responses appear much more ordered, with a stable phase relationship between circadian shifts in heart rate and mean aortic pressure. Since the latter stability is more normal, the assumption is made that the animal had become adjusted to its situation. Imposition of a daily lower body negative pressure (LBNP) stress shows characteristic responses.

Mccutcheon, E. P.↗
NASA NTRS1981

Effects of the Cosmos 1129 Soviet paste diet on body composition in the growing rat

Six Simonsen albino rats (45 days of age) were placed on a regimen of 40 g/day the semipurified Soviet paste diet used in the 18.5 day Cosmos 1129 spacecraft was to support the rats for various experiments on the physiological effects of weightlessness. The animals were maintained on the Soviet paste diet for 35 days, metabolic rate was measured and body composition was determined by direct analysis. The results were compared with a control group of rates of the same age, which had been kept on a standard commercial grain diet during the same period of time.

Pace, N.↗
NASA NTRS1980

Scaling of metabolic rate on body mass in small laboratory mammals

The scaling of metabolic heat production rate on body mass is investigated for five species of small laboratory mammal in order to define selection of animals of metabolic rates and size range appropriate for the measurement of changes in the scaling relationship upon exposure to weightlessness in Shuttle/Spacelab experiment. Metabolic rates were measured according to oxygen consumption and carbon dioxide production for individual male and female Swiss-Webster mice, Syrian hamsters, Simonsen albino rats, Hartley guinea pigs and New Zealand white rabbits, which range in mass from 0.05 to 5 kg mature body size, at ages of 1, 2, 3, 5, 8, 12, 18 and 24 months. The metabolic intensity, defined as the heat produced per hour per kg body mass, is found to decrease dramatically with age until the animals are 6 to 8 months old, with little or no sex difference. When plotted on a logarithmic graph, the relation of metabolic rate to total body mass is found to obey a power law of index 0.676, which differs significantly from the classical value of 0.75. When the values for the mice are removed, however, an index of 0.749 is obtained. It is thus proposed that six male animals, 8 months of age, of each of the four remaining species be used to study the effects of gravitational loading on the metabolic energy requirements of terrestrial animals.

Pace, N.↗
NASA NTRS1979

Methodology for estimation of total body composition in laboratory mammals

A standardized dissection and chemical analysis procedure was developed for individual animals of several species in the size range mouse to monkey (15 g to 15 kg). The standardized procedure permits rigorous comparisons to be made both interspecifically and intraspecifically of organ weights and gross chemical composition in mammalian species series, and was applied successfully to laboratory mice, hamsters, rats, guinea pigs, and rabbits, as well as to macaque monkeys. The procedure is described in detail.

Pace, N.↗
NASA NTRS1979

Continuous metabolic and cardiovascular measurements on a monkey subject during a simulated 6-day Spacelab mission

A 10-kg male pig-tailed monkey (Macaca nemestrina) was selected as an optimal species for spaceflight studies on weightlessness. Three days before the simulated launch, the animal was placed in a fiberglass pod system to provide continuous measurement of respiratory gas exchange. Attention is given to examining the effects of weightlessness on several basic parameters of metabolic and cardiovascular function in an adult nonhuman primate. The 10.7-day total simulated-experiment period consisted of preflight 2.6 days, inflight 6.3 days, and postflight 1.8 days. Statistically significant diurnal variation was noted in oxygen consumption and CO2 production rates, body temperature and HR, but not in respiratory quotient or blood pressure. The high quality of the continuous data obtained demonstrates the feasibility of performing sound physiological experimentation on nonhuman primates in the Spacelab environment.

Pace, N.↗
NASA NTRS1978

Continuous metabolic and cardiovascular measurements on a monkey subject during a simulated 6-day Spacelab mission

An adult male pig-tailed monkey (Macaca nemestrina) with surgically implanted biotelemetry unit was inserted into a fiberglass pod system which was installed in a Spacelab mock-up to simulate a 6-day mission during which extensive physiological measurements were obtained. The purpose of the pod was to make possible the study of respiratory gas exchange. Body temperature and selected cardiovascular parameters were recorded continuously for 2.6 days prior to 'launch', 6.3 days during 'flight', and 1.8 days after 'landing'. The results are surveyed, and it is concluded that it is feasible to perform sound physiological experiments on nonhuman primates in the Spacelab environment

Pace, N.↗
NASA NTRS1977

Metabolic and cardiovascular adaptation, monkey. NASA SMD 3, project 76, experiment 44 conducted at NASA/JSC, 14-25 May 1977

The biomedical results from an experiment on a monkey subjected to space flight conditions are reported. A background history of the development and testing of an experiment system designed to permit measurement of physiological parameters in subhuman primates during continuous, comfortable, couch restraint for periods of up to 30 days is reviewed. Of major importance in the experimental design of the system was the use of a fiberglass pod, which could be sealed and subdivided into upper and lower parts, to monitor and control the physiological responses for various parts of the animal's body. The experiment was conducted within the Spacelab Simulator for a period of 11 days. Data recorded includes: Spacelab Simulator cabin temperature; ventilation rate; pod internal temperature; fraction percent oxygen; fraction percent carbon dioxide; oxygen consumption rate; carbon dioxide production rate; respiratory quotient; intrathoracic temperature; heart rate; mean aortic pressure; mean ventricular pressure; diurnal variation of parameters measured; comparison of mean preflight, flight, and postflight values of the parameters measured; and correlation matrix for the parameters measured.

Pace, N.↗
NASA NTRS1977

Physiological studies in space with nonhuman primates using the monkey pod

A completely enclosed module was constructed for continuously maintaining an unanesthetized adult 10-12 kg monkey in a physiologically stable state of comfortable restraint for periods of at least 10 days, either on the ground or in an orbiting spacecraft. Energy balance determinations made during three different tests using a giant rhesus (malaca nemestrina) are presented in charts and graphs.

Pace, N.↗
NASA NTRS1977

The pig-tailed monkey (Macaca nemestrina) as a space-flight candidate

Scientific attributes which make the pig-tailed monkey an optimal candidate for studing the nature of cardiovascular and respiratory adaptations in man during exposure to high altitutes for long periods of time include: a calm, quiet, patient temperament; a short tail and the presence of ischial callosities permitting comfortable seated restraint during long duration experiments; and the close phylogenetic relationships and comparable body size to man.

Pace, N.↗
NASA NTRS1977

Body composition changes in monkeys during long-term exposure to high acceleration fields

Adult male pig-tailed monkeys, weighing 10-14 kg, were subjected to continuous centrifuging stress for 7 months in acceleration fields up to 2.5 g. In vivo analytical techniques were used to evaluate parameters of body composition, body-fluid distribution, and hematology. Statistically significant losses in total body mass, lean body mass, total body water, extracellular water content and interstitial water content proportional to the level of high g were demonstrated.

Pace, N.↗
NASA NTRS1977

Continuous 30-day measurements utilizing the monkey metabolism pod

A fiberglass system was previously described, using which quantitative physiological measurements could be made to study the effects of weightlessness on 10 to 14 kg adult monkeys maintained in comfortable restraint under space flight conditions. Recent improvements in the system have made it possible to obtain continuous measurements of respiratory gas exchange, cardiovascular function, and mineral balance for periods of up to 30 days on pig-tailed monkeys. It has also been possible to operate two pods which share one set of instrumentation, thereby permitting simultaneous measurements to be made on two animals by commutating signal outputs from the pods. In principle, more than two pods could be operated in this fashion. The system is compatible with Spacelab design. Representative physiological data from ground tests of the system are presented.

Pace, N.↗
NASA NTRS1976

Results from the EPL monkey-pod flight experiments conducted aboard the NASA/Ames CV-990, May 1976

The participation of the Environmental Physiology Laboratory (EPL) in the general purpose laboratory concept verification test 3 is documented. The EPL Monkey-Pod Experiment was designed to incorporate a 10-12 kg, pig tailed monkey, Macaca nemestrina, into the pod and measure the physiological responses of the animal continously. Four major elements comprise the EPL Monkey-Pod Experiment System: (1) a fiberglass pod containing the instrumented monkey plus feeder and watering devices, (2) an inner console containing the SKYLAB mass spectrometer with its associated valving and electronic controls, sensing, control and monitoring units for lower body negative pressure, feeder activity, waterer activity, temperatures, and gas metabolism calibration, (3) an umbilical complex comprising gas flow lines and electrical cabling between the inner and outer console and (4) an outer console in principle representing the experiment support to be provided from general space craft sources.

Rahlmann, D. F.↗