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NASA NTRS1980

Insulin binding and glucose uptake of adipocytes in rats adapted to hypergravitational force

Rats were exposed to 4.15 g for 1 yr and weight and age matched, and lean noncentrifuged rats were used as control groups. Rats exposed to chronic hypergravity (hypergravic rats) were found to show lower ambient insulin levels, greater food intake with smaller body weight gain, and decreased size of isolated adipocytes. The ability of adipocytes from the hypergravic rats to bind insulin was increased. With Scatchard analysis, both number and affinity of receptors were increased. In contrast to the increased binding, glucose transport was found to be decreased in adipocytes from these animals. However, when the data were expressed as a percentage of maximal effect, the half maximal insulin effect for both the hypergravic and lean control groups was produced at an insulin concentration of 0.23 + or - 0.02 ng/ml, which was lower than the insulin concentration of 0.31 + or - 0.02 ng/ml for the weight-matched control group (P less than 0.05). This increased insulin sensitivity in the hypergravic group was accounted for by an increased number of receptors.

Kobayashi, M.↗

NASA NTRS1982

Effect of simulated weightlessness on energy metabolism in the rat

Results of measurements of food uptake and body weight changes occurring in rats suspended from a harness so that the antigravity muscles were not used for locomotion are presented. The rats were tested in pairs, with both in a harness but only one suspended off its hind legs; this section lasted 7 days. A second phase of the experiment involved feeding the nonsuspended rat the same amount of food the experimental rat had consumed the previous day. All rats experienced decreased in body weight and food intake in the first stage, while in the second stage the suspended rat lost more weight. The total oxygen uptake, CO2 output, and rate of C-14O2 production were depressed in the suspended rats, then returned to normal levels once the rats were back on the ground. It is concluded that the gross metabolic processes are unaffected by simulated weightlessness.

Jordan, J. P.↗

NASA NTRS1982

Effects of simulated increased gravity on the rate of aging of rats - Implications for the rate of living theory of aging

It was found that the rate of aging of 17 month old rats which had been exposed to 3.14 times normal gravity in an animal centrifuge for 8 months was larger than that of the controls as determined by the apparently elevated lipofuscin content in heart and kidney, reduced numbers and increased size of mitochondria of heart tissue, and inferior liver mitochondria respiration. Steady-state food intake per day per kg body weight, which is presumably proportional to rate of living or specific basal metabolic expenditure, was found to be about 18 percent higher than in the controls after an initial 2 month adaptation period. Although half of the centrifuged animals lived only a little shorter than the controls (average about 343 vs. 364 days on the average, statistically nonsignificant), the remaining half (longest survivors) lived on the centrifuge an average of 520 days (range 483-572) compared to an average of 574 days (range 502-615) for the controls, computed from the onset of centrifugation, or 11 percent shorter. These findings indicate that a moderate increase of the level of basal metabolism of young adult rats adapted to hypergravity compared to controls in normal gravity is accompanied by a roughly similar increase in the rate of organ aging and reduction of survival, in agreement with Pearl's (1928) rate of living theory of aging, previously experimentally demonstrated only in poikilotherms.

Economos, A. C.↗

NASA NTRS1989

Gravitational biology and the mammalian circadian timing system

Using published reports, this paper compares and contrasts results on the effects of altered gravitational fields on the regulation in mammals of several physiological and behavioral variables with the circadian regulation of the same variables. The variables considered include the temperature regulation, heart rate, activity, food intake, and calcium balance. It is shown that, in rats, the homeostatic regulation of the body temperature, heart rate, and activity becomes depressed following exposure to a 2 G hyperdynamic field, and recovers within 6 days of 1 G condition. In addition, the circadian rhythms of these variables exhibit a depression of the rhythm amplitude; a recovery of this condition requires a minimum of 7 days.

Fuller, Charles A.↗

NASA NTRS1992

Alterations in glucose and protein metabolism in animals subjected to simulated microgravity

Reduction of physical activity due to disease or environmental restraints, such as total bed rest or exposure to spaceflight, leads to atrophy of skeletal muscle and is frequently accompanied by alterations in food intake and the concentration of metabolic regulatory hormones such as insulin. Hindlimb suspension of laboratory rats, as a model for microgravity, also shows marked atrophy of gravity-dependent muscles along with a reduced gain in body weight. Suspended rats exhibit enhanced sensitivity to insulin-induced glucose uptake when compared with normal control rats and resistance to insulin action when compared with control rats matched similarly for reduced body weight gain. These changes are accompanied by decreased insulin binding and tyrosine kinase activity in soleus but not plantaris muscle, unchanged glucose uptake by perfused hindlimb and decreased sensitivity but not responsiveness to insulin-induced suppression of net proteolysis in hindlimb skeletal muscle. These findings suggest that loss of insulin sensitivity during muscle atrophy is associated with decreased insulin binding and tyrosine kinase activity in atrophied soleus muscle along with decreased sensitivity to the effects of insulin on suppressing net protein breakdown but not on enhancing glucose uptake by perfused hindlimb.

Mondon, C. E.↗

NASA NTRS1990

Fed, but not Fasted, Adrenalectomized Rats Survive the Stress of Hemorrhage and Hypovolemia

We have recently shown that conscious adrenalectomized rats exhibit nearly normal recovery of arterial blood pressure during the 5 h after hemorrhage. In those experiments, it appeared that a previous reduction in food intake might have compromised the recovery of blood pressure and increased mortality. These experiments were designed to test in conscious sham-adrenalectomized (control) and adrenalectomized rats prepared with indwelling arterial and venous cannulae: 1. The effects of a 20- to 24-h fast (compared to rats fed ab libitum) on the mobilization of plasma substrates and recovery of arterial blood pressure after a 15 ml/kg - 5 min hemorrhage, and 2. Vascular responsivity to pressor agents in fed or fasted groups before or 2 h after hemorrhage. In all rats hemorrhage resulted in decreased arterial pressure and heart rate. Arterial pressure recovered to near normal in both fed and fasted control groups and in the led adrenalectomized rats, and all of these rats survived for 24 h after stress. By contrast, in the fasted adrenalectomized rats, arterial pressure recovered only during the first 1.5 - 2 h and then failed, resulting in 100% mortality by 3-5 h. Compared to the other three groups, in which substrate levels either increased or remained fairly stable, plasma glucose and beta-hydoxybutyrate concentrations fell steadily, from 1.5-2 h after hemorrhage until death occurred in the fasted adrenalectomized rats. Basal ACTH concentrations were elevated cormpared to control values in both adrenalectomized groups (fed and fasted). Hemorrhage caused increases in plasma ACTH in all groups; the magnitude of the responses did not differ among the groups. The dilution of Evans' blue dve after hemorrhage (used as an index of fluid movement into the vascular space) was not different in contol and adrenalectomized rats (either fed or fasted). There were no differences in pressor responses to phenylephrine, vasopressin, or angiotensin-II between the fed and fasted condition in the control rats either before or after hemorrhage. There was a fasting-associated decrease in vascular responsivity, to vasopressin, but normal responsivity to phenylephrine and angiotensin-II, in the adrenal-ectomized rats both before and after hemorrhage. We conclude that: (1) since fed adrenalectomized rats all survived the stress, adrenal hormones are not required for survival unless fasting is a prior condition; (2) vascular responsiveness to phenylephrine and angiotensin-II is not altered by fasting and is, therefore, probably not the proximate cause of cardiovascular svstem failure; and (3) from these data we cannot distinguish between a failure in substrate supply and a failure in some component of the cardiovascular svstem, other than vascular responsivity, that results in death after hemorrhage in fasted adrenalectomized rats.

Darlington, Daniel N.↗

NASA NTRS1976

Bone Formation Rate in Experimental Disuse Osteoporosis in Monkeys

Specific mechanisms underlying weightless and hypodynamic bone loss are obscure. A principal relationship which must be affected is the balance between bone formation and bone resorption rates. In order to better define the influence of those parameters on bone loss, and also to develop measurements in other species as a useful adjunct to human research, studies were undertaken with experimental monkeys. Tests were conducted with a total of 6 adult male monkeys, weighing 10-13 kg, and approximately 10-12 yrs. of age to evaluate specifically bone formation rate during the development of disuse osteoporosis and osteopenia. Three animals were restrained in a semi-recumbent position for six months; three animals served as normal caged controls. Food intake (Purina) was held relatively constant at 200g/day for each animal. Using a Norland Bone Mineral Analyzer, bone mineral losses of 3.5 to 6% were seen in the mid-shaft of the tibia and in the distal radius. Bone loss was confirmed radiographically, with observation of thinning of the proximal tibial cortex and trabeculae in the calcaneus. Bone formation rate was determined using standard Ca-47 kinetics under metabolic balance conditions. After six months of restraint, accretion was 7.2-13.2 mg Ca/kg/day, compared to 3.2-4.1 mg Ca/kg/day in caged controls and 3-8 mg Ca/kg/day in normal adult humans. Fecal and urine calcium was 25-40% higher in restrained animals than in controls. Dietary calcium absorption decreases during restraint, and calcium turnover increases, implying a rise in bone resorption rate concommitant with the observed rise in bone accretion rate. Further studies dealing specifically with bone resorption are underway to define this more fully.

Cann, Christopher↗

NASA NTRS2004

The Effect of Feeding Purified versus Chow Diet on Bone Changes Produced by Hindlimb Suspension of Female Rats

Spaceflight simulation studies use chow diets while spaceflight studies use a semi-purified &et. To determine whether the differences in these diets would affect the changes in unweighted bone, we compared the effects of purified vs chow diet on bone parameters, urinary calcium, plasma estradiol, and urinary corticosterone (CORT) in sexually mature female Sprague-Dawley rats. Rats fed purified AIN-93G or chow diet were kept ambulatory (AMB) or subjected to a spaceflight simulation model of unweighted hindlimbs (HLS) for 38 days. Body mass of treatment groups was similar although food intake and caloric density of the diets differed. Both HLS diet groups showed similar decreases in bone mineral content and mechanical strength in unweighted femurs compared to AMB (p<0.05). However, femur length was lower (p<0.05) in the chow-fed than AIN-93G fed groups. Urinary calcium excretion was greater in chow than AIN-93G fed rats, consistent with the higher level of calcium in the diet. Plasma estradiol was lower in HLS than in AMB fed AIN-93G, but similar in HLS and AMB chow fed groups. Femur mineral content was related to plasma estradiol (r(sup 2) =0.91, p<0.00l). Urinary CORT excretion was increased during initial HLS and elevated in HLS/chow-fed rats. Diets did not appear to affect the osteopenia induced by unweighting, but effects on bone growth, calcium excretion, plasma estradiol and urinary CORT do not support the view that these diets can by used interchangeably in bone studies.

Tou, Janet↗

NASA NTRS1999

Cortisol, insulin and leptin during space flight and bed rest

Most ground based models for studying muscle atrophy and bone loss show reasonable fidelity to the space flight situation. However there are some differences. Investigation of the reasons for these differences can provide useful information about humans during space flight and aid in the refinement of ground based models. This report discusses three such differences, the relationships between: (i) cortisol and the protein loss, (ii) cortisol and ACTH and (iii) leptin, insulin and food intake.

Flight Experiment↗

NASA NTRS1997

Gravity and body mass regulation

The effects of altered gravity on body mass, food intake, energy expenditure, and body composition are examined. Metabolic adjustments are reviewed in maintenance of energy balance, neural regulation, and humoral regulation are discussed. Experiments with rats indicate that genetically obese rats respond differently to hypergravity than lean rats.

NASA Discipline Regulatory Physiology↗

NASA NTRS1992

Effect of oral calcium and calcium + fluoride treatments on mouse bone properties during suspension

The bone effects of oral dosages of calcium chloride with or without supplementary sodium fluoride were assessed in antiorthostatically suspended mice. Two calcium dosages were used to replace half (3.1 mM) or all(6.3 mM) of the dietary calcium lost due to reduced food intake by the suspended mice. Two groups of 6.3 mM CaCl2-treated mice were additionally treated with 0.25 or 2.5 mM NaF. The results indicate that supplementation of the mouse drinking water with calcium salts prevents bone changes induced by short-term suspension, while calcium salts in combination with fluoride are less effective as fluoride dosage increases. However, the calcium supplements change the relationship between the femur mechanical properties and the mineral composition of the bone. Because of this, it appears that oral calcium supplements are effective through a mechanism other than simple dietary supplementation and may indicate a dependence of bone consistency on systemic and local fluid conditions.

Non-NASA Center↗

NASA NTRS1992

Effects of eating on vection-induced motion sickness, cardiac vagal tone, and gastric myoelectric activity

This study investigated the effect of food ingestion on motion sickness severity and its physiological mechanisms. Forty-six fasted subjects were assigned either to a meal group or to a no-meal group. Electrogastrographic (EGG) indices (normal 3 cpm activity and abnormal 4-9 cpm tachyarrhythmia) and respiratory sinus arrhythmia (RSA) were measured before and after a meal and during a subsequent exposure to a rotating drum in which illusory self-motion was induced. The results indicated that food intake enhanced cardiac parasympathetic tone (RSA) and increased gastric 3 cpm activity. Postprandial effects on motion sickness severity remain equivocal due to group differences in RSA baseline levels. During drum rotation, dysrhythmic activity of the stomach (tachyarrhythmia) and vagal withdrawal were observed. Furthermore, high levels of vagal tone prior to drum rotation predicted a low incidence of motion sickness symptoms, and were associated positively with gastric 3 cpm activity and negatively with tachyarrhythmia. These data suggest that enhanced levels of parasympathetic activity can alleviate motion sickness symptoms by suppressing, in part, its dysrhythmic gastric underpinnings.

NASA Discipline Neuroscience↗

NASA NTRS2004

Do Integrins Mediate the Skeletal Response to Altered Loading?

In vivo experiments were performed to examine the role of B1 integrin in skeletal adaptation to reduced and increased loading. Transgenic mice were generated with a dominant negative form of the B1 integrin cytoplasmic domain with expression driven by the osteocalcin promoter (pOCb1DN). This fragment consists of the transmembrane and intracellular domains and interferes with endogenous integrin signalling in vitro. This promoter targets expression of the transgene to mature bone cells. Expression of the transgene was confirmed by immunoprecipitation and western blotting. Reduced loading was generated by hindlimb suspension and increased loading the resumption of normal loading following hindlimb suspension. Two groups of female 35-day old mice were examined: poCb1DN transgenic mice (TG) and wild-type littermate controls (WT). Animals were hindlimb suspended for 1 week (HU, n = l0/gp) or 4 weeks (HU, n = 4 - 7/gp) or suspended for 4 weeks followed by reloading by normal ambulation for 4 weeks (RL, n = l0/gp). Age-matched controls (CT) were pairfed based on the HU food intake. The protocols were approved by the NASA Ames Research Center IACUC. Upon completion of the experimental protocol, body mass was recorded and tissues of interest removed and analyzed following standard procedures. Femoral whole bone structural behavior was measured in torsion to failure to obtain whole bone strength (failure torque) and torsional rigidity. Ash content (ash) and fraction (% ash) were determined for the tibia. Total ash is indicative of bone size whereas %ash is a material property. Tibial curvature was measured from microradiographs. For each experiment, the effects of genotype (TG, WT) and treatment (CT, HU/RL) were assessed by two-factor ANOVA followed by the Tukey-Kramer posthoc to identify significant differences at an alpha level of 0.05. Our goal was to understand differences resulting from altered integrin function in the adaptation to altered loading.

vanderMeulen, Marjolein C. H.↗

NASA NTRS2005

The effect of purified compared with nonpurified diet on bone changes induced by hindlimb suspension of female rats

The purpose of this study was to compare the bone changes induced by unloading in rats fed different diets, because space flight studies use a semipurified diet, whereas space flight simulation studies typically use nonpurified diets. Female Sprague-Dawley rats were fed a purified American Institute of Nutrition (AIN) 93G diet or a standard nonpurified diet and kept ambulatory or subjected to unloading by hindlimb suspension (HLS) for 38 days. Bone mineral content (BMC), mechanical strength, and factors related to the diet that affect bone (i.e., urinary calcium excretion, estradiol, and corticosterone) were measured. Average food intakes (grams per day) differed for diets, but caloric intake (kilocalories per day) and the final body masses of treatment groups were similar. The HLS-induced decrease in femoral BMC was not statistically different for rats fed a nonpurified diet (-8.6%) compared with a purified AIN-93G diet (-11.4%). The HLS-induced decrease in femoral mechanical strength was not statistically different for rats fed a nonpurified diet (-24%) compared with a purified AIN-93G diet (-31%). However, bone lengths were decreased (P < 0.05) in rats fed a nonpurified diet compared with a purified diet. Plasma estradiol levels were lower (P < 0.05) in the HLS/AIN-93G group but similar in the HLS and ambulatory rats fed a nonpurified diet. Plasma estradiol was related to femoral BMC (r = 0.85, P < 0.01). Urinary calcium excretion was higher (P < 0.05) in rats fed a nonpurified diet than those fed a purified AIN-93G diet, which is consistent with the higher level of calcium in the nonpurified diet. Urinary corticosterone levels were higher (P < 0.05) in rats fed a nonpurified diet than rats fed the AIN-93G diet. Although the osteopenia induced by unloading was similar in both diet groups, there were differences in longitudinal bone growth, calcium excretion, plasma estradiol levels, and urinary corticosterone levels. Results indicate that the type of standard diet used is an important factor to consider when measuring bone end points.

Bone and Bones/pathology↗

NASA NTRSDate not supplied

EVA Planning: Using Neutral Buoyancy Laboratory (NBL) Training to Predict in-Flight Energy Expenditure

Metabolic rate (“met rate”) is the amount of energy expended over a period of time and is influenced by many factors including body composition, level of physical activity, resting metabolic rate, sex, age, and food intake. Met rate is measured during Extravehicular Activity (EVA) training at the Neutral Buoyancy Laboratory (NBL) and during in-flight EVAs through indirect calorimetry, calculating energy expenditure from respiratory measurements of O 2 consumption and/or CO 2 production. During Extravehicular Activity (EVA) planning, metabolic cost is important to consider and is used to inform EVA duration based on spacesuit consumables associated with life support systems. Currently, NBL and previous ISS EVA met rate data for specified crewmembers are utilized to predict in-flight EVA metabolic costs based on a proposed EVA timeline. Timeline data collected during training is used to relate met rates to specific EVA activities, which are in turn assigned to more generalized EVA task categories, categorizing by both task type and restraint type. EVA task categories include EVA Setup/Cleanup, Worksite Setup/Cleanup, Cable Routing, Bolts, Fluid Connectors, Electrical Connectors, R&R Work, Miscellaneous Work, Incapacitated Crew Rescue (being rescued or performing), Assisted Crew Rescue (being assisted or performing), and Translation. Restraint types consist of Free-Float, Body Restraint Tether (BRT), Articulating Portable Foot Restraint (APFR), and Space Station Remote Manipulator System (SSRMS). From a crewmember’s historical data, individualized 10th, 50th and 90th percentile met rate estimates are generated for each task category and used to estimate the proposed EVA timeline metabolic cost. In-flight metabolic data (“As-Executed”) from recent ISS US EVAs 85-88 (totaling eight EVA crewmember met rates) was compared with their predicted metabolic cost (“As-Planned”) to evaluate the accuracy of the current met rate estimation method. Across the four EVAs, As-Executed Cumulative EVA Total Metabolic Cost (M = 5893.78 BTU, SD = 816.60) was not significantly different compared to As-Planned Cumulative EVA Total Metabolic Cost (M = 6106.60 BTU, SD = 826.62; t(7) = 0.751 , p = .477). Though not a significant difference, generally, As-Planned total estimates were slightly higher than As-Executed total metabolic cost. Relative Error for Cumulative EVA Total Metabolic Cost ranged from -33% to 14.7%, depending on the crewmember and EVA. When comparing As-Planned to A-Executed EVA task categories for Bolts, Electrical Connectors, EVA Cleanup, EVA Setup, Miscellaneous Work, Translation, Worksite Cleanup, and Worksite Setup during these EVAs, no significant differences were observed, however, there was a significant difference in As-Planned (M = 783.71 BTU, SD = 408.88) compared to As-Executed (M = 608.87 BTU, SD = 425.29) metabolic cost for the task category of Repair-and-Replace (R&R) Work (t(17) = 3.21 , p = .005). Looking closer within the R&R Work task category, As-Executed R&R Work with Free-Float restraint type (M = 706.17 BTU, SD = 352.18) was significantly less than As-Planned R&R Work with Free-Float restraint type (M= 887.96 BTU, SD = 381.42; t(12) = 2.59, p < .024). As-Executed R&R Work with SSRMS Restraint type (M = 355.89 BTU, SD = 534.65) was not significantly different from As-Planned values (M = 512.69 BTU, SD = 383.34; t(4) = 1.88, p = 0.132). These findings suggest that the energy expended performing R&R Work (Free-Float) is lower in flight than predicted. Accurate predictions of the metabolic cost of EVA are essential for planning and executing successful ISS EVAs. Overall, the current met rate prediction method is similar to actual in-flight values, slightly erring on the side of overestimation. Future work includes analysis of more historical in-flight EVA data to increase the power of the analysis, evaluating the NBL-ISS met rate conversion factor between NBL and ISS tasks, as well as exploring methods of substitution when crewmembers are missing prior task category data.

Lauren Cox↗

NASA NTRS1987

Physiological responses during whole body suspension of adult rats

The objective of this study was to characterize responses of adult rats to one and two weeks of whole body suspension. Body weights and food and water intakes were initially reduced during suspension, but, while intake of food and water returned to presuspension levels, body weight remained depressed. Diuresis was evident, but only during week two. Hindlimb muscle responses were differential, with the soleus exhibiting the greatest atrophy and the EDL a relative hypertrophy. These findings suggest that adult rats respond qualitatively in a manner similar to juveniles during suspension.

Steffen, J. M.↗

NASA NTRS2000

Estimation of the oxalate content of foods and daily oxalate intake

BACKGROUND: The amount of oxalate ingested may be an important risk factor in the development of idiopathic calcium oxalate nephrolithiasis. Reliable food tables listing the oxalate content of foods are currently not available. The aim of this research was to develop an accurate and reliable method to measure the food content of oxalate. METHODS: Capillary electrophoresis (CE) and ion chromatography (IC) were compared as direct techniques for the estimation of the oxalate content of foods. Foods were thoroughly homogenized in acid, heat extracted, and clarified by centrifugation and filtration before dilution in water for analysis. Five individuals consuming self-selected diets maintained food records for three days to determine their mean daily oxalate intakes. RESULTS: Both techniques were capable of adequately measuring the oxalate in foods with a significant oxalate content. With foods of very low oxalate content (<1.8 mg/100 g), IC was more reliable than CE. The mean daily intake of oxalate by the five individuals tested was 152 +/- 83 mg, ranging from 44 to 352 mg/day. CONCLUSIONS: CE appears to be the method of choice over IC for estimating the oxalate content of foods with a medium (>10 mg/100 g) to high oxalate content due to a faster analysis time and lower running costs, whereas IC may be better suited for the analysis of foods with a low oxalate content. Accurate estimates of the oxalate content of foods should permit the role of dietary oxalate in urinary oxalate excretion and stone formation to be clarified. Other factors, apart from the amount of oxalate ingested, appear to exert a major influence over the amount of oxalate excreted in the urine.

NASA Discipline Regulatory Physiology↗

NASA NTRS1999

Fluid and Electrolyte Nutrition

Studies of fluid and electrolyte homeostasis have been completed since the early human space flight programs, with comprehensive research completed on the Spacelab Life Sciences missions SLS-1 and SLS-2 flights, and more recently on the Mir 18 mission. This work documented the known shifts in fluids, the decrease in total blood volume, and indications of reduced thirst. Data from these flights was used to evaluate the nutritional needs for water, sodium, and potassium. Interpretations of the data are confounded by the inadequate energy intakes routinely observed during space flight. This in turn results in reduced fluid intake, as food provides approximately 70% water intake. Subsequently, body weight, lean body mass, total body water, and total body potassium may decrease. Given these issues, there is evidence to support a minimum required water intake of 2 L per day. Data from previous Shuttle flights indicated that water intake is 2285 +/- 715 ml/day (mean +/- SD, n=26). There are no indications that sodium intake or homeostasis is compromised during space flight. The normal or low aldosterone and urinary sodium levels suggest adequate sodium intake (4047 +/- 902 mg/day, n=26). Because excessive sodium intake is associated with hypercalciuria, the recommended maximum amount of sodium intake during flight is 3500 mg/day (i.e., similar to the Recommended Dietary Allowance, RDA). Potassium metabolism appears to be more complex. Data indicate loss of body potassium related to muscle atrophy and low dietary intake (2407 +/- 548 mg/day, n=26). Although possibly related to measurement error, the elevations in blood potassium suggest alterations in potassium homeostasis. The space RDA for minimum potassium intake is 3500 mg/day. With the documented inadequate intakes, efforts are being made to increase dietary consumption of potassium.

Lane, Helen W.↗