Biomedical subjects

R C Dennis

Publications and source records attributed to R C Dennis.

At least 19 recordsLinked to original sources

PubMed2001

Survival, function, and hemolysis of shed red blood cells processed as nonwashed blood and washed red blood cells.

BACKGROUND: Shed nonwashed blood and shed washed red blood cells (RBC) are being used as alternatives to allogeneic liquid-preserved RBC for patients during thoracic and cardiovascular surgical procedures. METHODS: Mongrel dogs were bled a volume of blood into the abdominal cavity and the shed blood was reinfused as nonwashed blood or washed RBC. The 51Cr RBC volumes were measured before, immediately after, and 24 hours after the exchange transfusion to assess the recovery of the shed RBC and the 24-hour posttransfusion survival. Compatible dogs were given allogeneic transfusions of 51Cr-labeled nonwashed blood and washed RBC, and 24-hour posttransfusion survival and half-life were measured. RESULTS: Immediately after the 100% exchange transfusion, the recovery value was 62% for the nonwashed shed blood and 82% for the washed RBC. Both the nonwashed blood and the washed RBC had 24-hour posttransfusion survival values of 90% and normal oxygen transport function after the exchange transfusion. Compatible allogeneic 51Cr-labeled nonwashed blood and washed RBC had normal 24-hour posttranfusion survival and 51Cr half-life values. CONCLUSIONS: The survival, function, and hemolysis of shed nonwashed blood and shed washed RBC were similar to fresh blood in the dog that underwent a 100% exchange transfusion.

Animals↗

PubMed2001

Survival and function of baboon RBCs released from clotted blood and washed before autologous transfusion.

BACKGROUND: One alternative to an allogeneic transfusion is the salvaging of the patient's own shed blood. In this study, baboon blood was allowed to clot and the RBCs that were released from the clotted blood lysed with and without urokinase were washed before autologous transfusion. STUDY DESIGN AND METHODS: Forty-four studies were done in 13 baboons (Papio cynocephalus or Papio anubis) over a 3-year period. In 24 studies, a 50-mL volume of blood was collected without an anticoagulant and stored at 22 degrees C for as long as 72 hours before washing and autologous transfusion. In 20 other studies, a 50-mL volume of blood was collected without an anticoagulant and allowed to clot for 30 to 60 minutes. Urokinase, ranging from 2,500 to 10,000 units per mL, was added, and the blood was stored at 22 degrees C for 24 hours before washing and autologous transfusion. RESULTS: RBCs that were stored at 22 degrees C without urokinase for 24 hours exhibited an in vitro recovery value of 45 percent, a (51)Cr 24-hour posttransfusion survival of 86 percent, and an index of therapeutic effectiveness of 39 percent. The (51)Cr T(50) value was normal at 14 days, and RBC oxygen-transport function was slightly reduced. RBCs that were stored at 22 degrees C for 24 hours with 10,000 units per mL of urokinase exhibited an in vitro recovery value of 89 percent, a (51)Cr 24-hour posttransfusion survival value of 86 percent, and an index of therapeutic effectiveness of 76 percent. The (51)Cr T(50) value was normal at 14 days, and the RBC oxygen-transport function was only slightly reduced. CONCLUSION: Autologous baboon RBCs isolated from clotted blood treated or not treated with urokinase and washed before transfusion have excellent survival and normal or only slightly reduced oxygen-transport function.

Animals↗

PubMed1998

Guidelines on admission and discharge for adult intermediate care units. American College of Critical Care Medicine of the Society of Critical Care Medicine.

OBJECTIVE: To present guidelines for writing admission and discharge policies for adult intermediate care units. DATA SOURCES: Opinion of practitioners with experience and expertise in managing critical and intermediate care units. DATA SYNTHESIS: Consensus was reached regarding the characteristics of patients best suited for management in an intermediate care unit, as supported by a literature review. CONCLUSION: Criteria were developed that define patients who are optimal candidates for management in an intermediate care unit.

Adult↗

PubMed1996

Altitude acclimatization and blood volume: effects of exogenous erythrocyte volume expansion.

We studied sea-level residents during 13 days of altitude acclimatization to determine 1) altitude acclimatization effects on erythrocyte volume and plasma volume, 2) if exogenous erythrocyte volume expansion alters subsequent erythrocyte volume and plasma volume adaptations, 3) if an increased blood oxygen content alters erythropoietin responses during altitude acclimatization, and 4) mechanisms responsible for plasma loss at altitude. Sixteen healthy men had a series of hematologic measurements made at sea level, on the first and ninth days of altitude (4,300 m) residence, and after returning to sea level. Twenty-four hours before the ascent to altitude, one group received a 700-ml infusion of autologous erythrocytes (42% hematocrit), whereas the other group received only a saline infusion. Erythrocyte infusion increased erythrocyte volume by approximately 10%, whereas saline infusion had no effect; in addition, initially at altitude, blood oxygen content was 8% higher in erythrocyte-infused than in saline-infused subjects. The new findings regarding altitude acclimatization are summarized as follows: 1) erythrocyte volume does not change during the first 13 days and is not affected by prior exogenous expansion, 2) a modest increase in blood oxygen content does not modify erythropoietin responses, 3) plasma losses are related to vascular protein losses, and 4) exogenous erythrocyte volume expansion coincides with transient increases in plasma loss, vascular protein loss, and mean arterial pressure elevation. These findings better define human blood volume responses during altitude acclimatization.

Acclimatization↗

PubMed1994

The efficacy of sequential compression devices in multiple trauma patients with severe head injury.

Thirty-two multiple trauma patients with severe head injury and a Glasgow Coma Scale (GCS) score of 8 or less were prospectively studied to assess the occurrence of deep venous thrombosis (DVT) and pulmonary embolism (PE). All patients required mechanical ventilation. A sequential compression device (SCD) was used in 14 patients and 18 patients received no prophylaxis for thromboembolism. Bilateral lower extremity technetium venoscans and ventilation/perfusion (V/Q) lung scans were performed within 6 days of admission and every week for 1 month or until the patient developed DVT or PE or was discharged from the SICU. Deep venous thrombosis occurred in two patients (6%) at 16 and 28 days following trauma. Twenty-five patients had normal or low probability V/Q scans. Six had high probability V/Q scans confirmed by pulmonary arteriograms (PAGs) at 12.5 +/- 4 days. Clinical signs of PE were absent in all patients with a positive PAG. There were no differences in age, Injury Severity Score (ISS), GCS Score, APACHE II Score, or Trauma Score between the patients who developed DVT or PE and those who did not. A SCD was used in four of the eight patients with DVT or PE. All but one patient with DVT or PE underwent placement of a vena caval filter. Multiple trauma patients with severe head injury (GCS score < or = 8) are at high risk for thromboembolism. The available means of prevention and diagnosis of DVT or PE in multiple trauma patients with severe head injury are not entirely effective.

Adult↗

PubMed1993

Role of thermal factors on aerobic capacity improvements with endurance training.

This investigation studied the importance of the rise in body temperature during exercise for aerobic capacity adaptations produced by endurance training. The approach used was to compare training effects produced by subjects exercising in hot (35 degrees C) water vs. cold (20 degrees C) water. Hot water was used to potentiate, and cold water to blunt, the rise in body temperature during exercise. Eighteen young men trained by cycle-ergometer exercise at 60% of maximal oxygen uptake (VO2max) while immersed to the neck in either hot (HWT, n = 9) or cold (CWT, n = 9) water for 60 min, 5 days/wk, for 8 wk. Before and after training, VO2max, erythrocyte volume, plasma volume, and vastus lateralis citrate synthase activity were measured. Training increased (P < 0.01) VO2max by 13%, with no difference between HWT and CWT in the magnitude of the effect. Erythrocyte volume increased 4% (P < 0.01) with training, with no difference between HWT and CWT in the magnitude of the effect. Plasma volume remained unchanged by training in both the HWT and CWT groups. Last, vastus lateralis citrate synthase activity increased by 38% with training, but there was no difference between HWT and CWT in the training effect. Thus, exercise-induced body temperature elevations are not an important stimulus for the aerobic adaptations to moderate-intensity endurance training.

Adaptation, Physiological↗

PubMed1992

Nutritional outcome and pneumonia in critical care patients randomized to gastric versus jejunal tube feedings. The Critical Care Research Team.

OBJECTIVE: To compare nutritional status, gastric colonization, and rates of nosocomial pneumonia in ICU patients randomized to gastric tube feeding vs. patients fed by an endoscopically placed jejunal tube. DESIGN: Randomized, prospective study. SETTING: Medical and surgical ICUs at Boston City Hospital; surgical ICU at University Hospital. PATIENTS: Of the 38 study patients, 19 were randomized to gastric tube feeding and 19 were randomized to an endoscopically placed jejunal tube. The two groups were similar in age, sex, race, underlying disease, and type of surgery. RESULTS: The two patient groups were similar in number of days fed, duration of ICU stay, duration of mechanical ventilation, days of antibiotic therapy, and days with fever. Compared with the gastric group, the jejunal group had more patients with circulatory shock on admission (79% vs. 68.4%), higher admission Acute Physiology Score (24.0 vs. 21.7), and fewer patients with pneumonia at randomization (26.3% vs. 31.6%). The jejunal group received a significantly higher percentage of their daily goal caloric intake (p = .05), and had greater increases in serum prealbumin concentrations (p < .05) than the patients with gastric tube feeding. Although the jejunal tube group had more days of diarrhea (3.3 +/- 6.6 vs. 1.8 +/- 2.9), this difference was not statistically significant. Nosocomial pneumonia was diagnosed clinically in two (10.5%) patients in the gastric tube group and in no patients in the jejunal tube group. CONCLUSIONS: Patients fed by jejunal tube received a significantly higher proportion of their daily goal caloric intake, had a significantly greater increase in serum prealbumin concentrations, and had a lower rate of pneumonia than patients fed by continuous gastric tube feeding.

Adult↗

PubMed1992

Poor predictive value of hematocrit and hemodynamic parameters for erythrocyte deficits after extensive elective vascular operations.

Fluid resuscitation and transfusion therapy are particularly critical in patients undergoing extensive vascular operations because of diffuse atherosclerosis and the risk of perioperative myocardial infarction. Sophisticated perioperative monitoring has reduced the mortality rate substantially, but indications for transfusion remain controversial. We determined erythrocyte volume, (EV), total blood volume (TBV) and plasma volume (PV) preoperatively and 18 to 24 hours postoperatively in 41 elderly patients (68.8 +/- 1.3 years) undergoing elective vascular operations (30 abdominal aortic aneurysmorrhaphy, ten aortofemoral bypass and one carotid endarterectomy). EV was measured using 51chromium-labeled autologous erythrocytes; TBV and PV were calculated from EV and total body hematocrit (peripheral venous hematocrit [HCT] x 0.89). Ideal blood volumes were calculated from nomograms based on body surface area and gender. Relationships between body volumes (percentage of ideal), simultaneously measured peripheral venous HCT and hemodynamic parameters heart rate, mean arterial pressure, central venous pressure, pulmonary capillary wedge pressure, cardiac index and systemic vascular resistance index were studied by stepwise regression. In 24 patients, blood volumes and hemodynamic parameters were also measured in the recovery room. HCT significantly correlated with EV at all three time periods (p less than 0.001), but the ability of HCT to predict EV in an individual patient was relatively poor (r = 0.50 preoperatively; r = 0.54 in recovery room and r = 0.66 24 hour postoperatively). By 24 hours postoperatively, EV had decreased to 78.3 +/- 2.4 percent of ideal EV (range of 47 to 112 percent). However, only two patients had HCT less than 30 despite the fact that 13 of 41 patients had an EV deficit of greater than 30 percent. No patient had a HCT of less than 25 percent. Hemodynamic parameters did not contribute to the prediction of EV, PV or TBV at any time. Two patients had myocardial infarctions postoperatively associated with 24 hour EV deficits of 18.5 and 29.6 percent. One patient died of a pulmonary embolus. Because of these findings, the concept of a "transfusion trigger" must be viewed with caution, since many patients undergoing vascular operations will have considerable EV deficits despite an "acceptable" HCT.

Age Factors↗

PubMed1992

Erythrocyte, plasma, and blood volume of healthy young men.

Insufficient data are readily available concerning the vascular fluid volumes of healthy young men. The primary purpose of this study was to develop a normative database for the erythrocyte volume, plasma volume, and blood volume of healthy young men. The secondary purposes were to relate these vascular fluid volumes to the person's body size and physical fitness level and to develop equations that enable their prediction. Fifty-one male soldiers with a mean age of 22 (range 18-35) yr and with a mean maximal aerobic power of 53 (range 42-65) ml O2.kg-1.min-1 had their lean body mass and vascular fluid volumes measured. Erythrocyte volume was measured by 51Cr, and plasma volume was measured by 125I. The findings concerning the erythrocyte volume, plasma volume, and blood volume of these young men are summarized as follows: 1) these vascular fluid volumes are accurately predicted from several indices of body size; 2) lean body mass is the anthropometric index that is most closely correlated to these vascular fluid volumes; 3) the erythrocyte volumes for a given body surface area are lower, particularly for large individuals, than values previously reported in surveys of undefined populations; 4) aerobic fitness is generally not related to vascular volumes; and 5) F-cell ratio is not related to aerobic fitness.

Adolescent↗

PubMed1991

Effect of graft material on loss of erythrocytes after aortic operations.

It has been suggested that loss of erythrocytes after abdominal aortic grafting is influenced by the type of synthetic graft used. A prospective randomized study was done to compare loss of erythrocytes in patients receiving Dacron (polyester fiber, Meadox woven double velour) and Gore-Tex (polytetrafluoroethylene [PTFE]) grafts during the perioperative period. A total of 25 patients (13 Dacron and 12 PTFE) was studied, including 21 with abdominal aortic aneurysms and four with aortoiliac occlusive disease. Erythrocyte volume (EV) was measured using 51Cr-labeled autologous erythrocytes on the day prior to the operation, one to two hours after the operation when the patients were hemodynamically stable and 24 hours postoperatively. In addition to measurements of 51Cr EV and the volume of intraoperatively salvaged washed erythrocytes, the length of storage of the units of homologous liquid preserved erythrocytes at 4 degrees C. prior to transfusion were recorded. The mean intraoperative erythrocyte loss (+/- S.D.) for the Dacron group was 892 +/- 543 milliliters and for the PTFE group, 842 +/- 403 milliliters (p = NS). Patients in the Dacron group received intraoperatively 2.2 +/- 1.6 (units +/- S.D.) milliliters with a range of zero to 4 units of homologous liquid preserved erythrocytes and patients in the PTFE group received 1.2 +/- 1.2 milliliters with a range of zero to 3 units of homologous liquid preserved erythrocytes (p = NS). The mean total loss of erythrocytes (+/- S.D.) was 1,055 +/- 649 milliliters for the Dacron group and 978 +/- 503 milliliters for the PTFE group (p = NS). Despite inherent differences in graft material, there were no significant differences in intraoperative or post-operative loss of erythrocytes or in the number of homologous units of liquid preserved erythrocytes transfused with a p value of less than 0.05 considered significant.

Aged↗

PubMed1989

The safety and therapeutic effectiveness of human red cells stored at -80 degrees C for as long as 21 years.

Human red cells frozen by various methods have been stored in the frozen state at -80 degrees C for as long as 21 years. This report discusses: red cells frozen with 42 percent weight per volume (wt/vol) glycerol in an ionic medium in a polyvinylchloride (PVC) plastic bag using the Cohn method; red cells frozen with 45 percent wt/vol glycerol in a low ionic medium in a PVC plastic bag using the Huggins method; red cells frozen with 40 percent wt/vol glycerol in an ionic medium in a polyolefin plastic bag using the Meryman-Hornblower method; and red cells frozen with 40 percent wt/vol glycerol in an ionic medium in a standard 600-ml or an elongated 800-ml PVC plastic primary collection bag with an adapter port using the Naval Blood Research Laboratory (NBRL) method. After frozen storage for as long as 21 years by the four methods described above, the thawed red cells were deglycerolized with 50 to 150 ml of 12 percent sodium chloride and 1.5 to 2.0 l of sodium chloride-glucose or sodium chloride-glucose-phosphate solution. After washing and storage at 4 degrees C for 24 hour, the red cells had a mean freeze-thaw-wash recovery value of 90 percent, a mean 24-hour posttransfusion survival value of 85 percent, a mean index of therapeutic effectiveness of 75 percent, normal or slightly impaired oxygen transport function, and minimal hemolysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Anticoagulants↗

PubMed1989

Control of thermoregulatory sweating during exercise in the heat.

The purposes of this study were the following: 1) to determine whether erythrocyte infusion alters the control of thermoregulatory sweating and 2) to demonstrate how increases and decreases of both plasma tonicity and blood volume influence the thermoregulatory control parameters of threshold temperature and sweating sensitivity. Six non-heat-acclimated and five heat-acclimated males attempted heat stress tests (HSTs) both before and shortly after (48-96 h) autologous erythrocyte infusion. The non-heat-acclimated subjects were euhydrated for both HSTs, whereas the heat-acclimated subjects were studied in a euhydrated and a hypohydrated (-5% body wt) condition both pre- and postinfusion (500 ml of solution containing approximately 60% hematocrit of autologous erythrocytes). The HSTs consisted of treadmill exercise (335 W.m-2) in a hot (35 degrees C, 45% relative humidity) environment, and esophageal temperature and local sweating rate were continuously measured during 25 min of exercise. These experiments resulted in a matrix of conditions where both plasma tonicity and blood volume were increased or decreased relative to control conditions (euhydration, preinfusion). The findings concerning thermoregulatory sweating during exercise in the heat were summarized as follows: 1) acute polycythemia decreases the threshold temperature and increases the sweating sensitivity, 2) both threshold temperature and sweating sensitivity are increased or decreased from control levels dependent on the combined influence of plasma tonicity and blood volume, and 3) equations are presented that describe how plasma tonicity and blood volume alter threshold temperature and sweating sensitivity values.

Acclimatization↗

PubMed1989

Human intravascular immunoglobulin responses to exercise-heat and hypohydration.

Several investigators have suggested that prolonged exercise and hypohydration alter the intravascular mass of immunoglobulins. Those studies, however, have methodological concerns which make generalizations from their data very tenuous. This study examined the effects of prolonged moderate intensity exercise in the heat and hypohydration on changes in the intravascular mass of immunoglobulins. Five heat-acclimated males attempted two Heat Stress Tests (HSTs). One HST was completed when subjects were euhydrated and the other HST when subjects were hypohydrated (-5% from base line body weight). The HSTs consisted of 30 min of rest in a 20 degrees C antechamber, followed by a 120-min exposure (2 repeats of 15 min rest and 45 min walking) in a hot (35 degrees C, 45% rh) environment. The following observations were made concerning immunoglobulin responses to hypohydration and exercise-heat stress: a) the changes in concentrations (mg.dl-1) of the measured immunoglobulins were often a reflection of changes in the plasma volume; b) hypohydration increased the intravascular mass (g) of the complement enzyme C3 during resting conditions, but did not alter the intravascular mass of IgG, IgA, and IgM, and c) prolonged treadmill exercise in the heat, when either euhydrated or hypohydrated, did not alter the intravascular mass of IgG, IgA, IgM, and C3. These data indicate that the intravascular mass of immunoglobulins does not change during prolonged moderate intensity exercise in the heat, and that hypohydration results in a translocation of C3 to the intravascular space. In addition, these data indicate that immunoglobulins do not provide a stress index for hypohydration.

Adult↗

PubMed1988

Total parenteral nutrition-induced cyclic hypercapnia.

Excessive rates of carbohydrate infusion during total parenteral nutrition (TPN) have been reported to cause hypercapnia leading to respiratory failure or inability to wean from a ventilator. This case history illustrates the hitherto unreported syndrome of cyclic hypercapnia resulting from high rates of carbohydrate infusion during peak TPN flow rates when TPN was provided in a cyclic fashion. The patient was given TPN daily over an 18 1/2-h period followed by 5 1/2 h without nutritional support. Elevated CO2 production, increased respiratory quotient, hypercapnia, and inability to wean from a ventilator occurred during peak cycle TPN flow rates. When the same carbohydrate load was infused continuously over a 24-h period, CO2 production, respiratory quotient and PaCO2 were reduced. The patient was then able to tolerate periods of unassisted ventilation.

Dietary Carbohydrates↗

PubMed1988

Polycythemia and hydration: effects on thermoregulation and blood volume during exercise-heat stress.

We studied the effects of autologous erythrocyte infusion on thermoregulation and blood volume during exercise in the heat. Specifically, we wanted to determine whether heat-acclimated subjects, as well as hypohydrated subjects, would have a thermoregulatory advantage from acute polycythemia during exercise in the heat. Five heat-acclimated males attempted four heat stress tests (HSTs): two pre- and two postinfusion. Autologous erythrocyte infusion was accomplished with 500 ml of a NaCl-glucose-phosphate solution containing approximately 60% hematocrit. One HST, both pre- and postinfusion, was done while subjects were euhydrated, and one HST was done while subjects were hypohydrated (-5% of body wt). After 30 min of rest in a 20 degrees C antechamber, the HST consisted of a 120-min exposure (2 repeats of 15 min rest and 45 min walking) in a hot (35 degrees C, 45% relative humidity) environment. The findings concerning acute polycythemia in heat-acclimated subjects are summarized: 1) polycythemia increased (P less than 0.05) sweating rate and reduced (P less than 0.01) core temperature during exercise-heat stress for both euhydrated and hypohydrated subjects; 2) the erythrocyte infusion caused an increased (P less than 0.05) plasma volume and increased (P less than 0.01) blood volume; 3) the increased plasma volume was associated with an increased (P less than 0.05) total circulating protein mass; 4) the increased total circulating protein mass tended to better maintain plasma volume when hypohydrated; and 5) heat acclimation may increase extravascular protein mass. Therefore, it is concluded that erythrocyte infusion provides a thermoregulatory advantage during exercise in the heat for heat acclimated subjects when both euhydrated and hypohydrated.

Acclimatization↗

PubMed1988

Effects of plasma administration on gram negative shock in granulocytopenic dogs.

We studied the effect of an infusion of citrated plasma on the hemodynamic response and bacterial clearance of acutely septic dogs rendered severely neutropenic with cyclophosphamide. Two hours after a 5 X 10(9)/kg intravenous injection of E. coli, neutropenic control dogs infused with 20 ml/kg of normal saline became hypotensive and remained so for the next 2 hr. In contrast, the infusion of 20 ml/kg of citrated plasma after the initiation of bacteremia was followed by a significant (P less than .01) improvement in the mean arterial pressure (MAP), compared to saline-treated animals. The effect of citrated plasma administration on MAP was unrelated to bacterial clearance or to improvement in cardiac output but was associated with an increase in total peripheral resistance that was sustained for 2 hr after plasma infusion. The infusion of hyperimmune plasma from dogs previously immunized to core glycolipid antigen appeared to have no important advantage over normal plasma. At the doses of plasma that were given, a relatively higher arterial pH was the only observed significant difference (P less than .05) when immune plasma was compared to normal plasma. Resuscitation of septic neutropenic dogs with large volumes of plasma deserves further study with respect to the specific mechanisms responsible for its beneficial effect.

Agranulocytosis↗

PubMed1988

A clinical experience with ADSOL preserved erythrocytes.

This study was undertaken to determine how ADSOL (adenine, glucose, mannitol and sodium chloride) preservative affects the 24 hour post-transfusion survival values of human erythrocytes during storage at 4 degrees C. for 35, 42 and 49 days. The results show that acceptable 24 hour post-transfusion survival values were observed only after storage at 4 degrees C. for 35 days.

Adenine↗

PubMed1988

Autologous red blood cell reinfusion: effects on stress and fluid regulatory hormones during exercise in the heat.

This study assessed the effects of induced erythrocythemia on stress and fluid regulatory hormones during walking exercise in the heat. Six unacclimated male subjects received approximately 600 ml of a sterile saline solution containing 50% volume-to-volume of autologous erythrocytes. Three heat stress tests (HSTs) were attempted: one approximately 2 weeks prior to the reinfusion procedure, a second 48 h after the reinfusion procedure, and a third 1 week later, corresponding to 9 d subsequent to reinfusion. Each HST comprised three consecutive 45-min exercise and 15-min rest intervals (VO2 approximately 2.0 L.min-1, 1.56 m.s-1, 6% incline, 35 degrees C, 45% rh). Blood was withdrawn before the HST and 30 min into each exercise (EX) bout. In all three HST's plasma cortisol (PC) levels were significantly (p less than 0.01) reduced during the first EX bout compared to preexercise levels, and then progressively increased during the second and third EX intervals during HST 1. During HST 2 (48 h postinfusion), however, PC levels were significantly (p less than 0.05) reduced in two blood samples (EX 2, 3) compared to the same blood samples from HST-1 (preinfusion). Plasma renin activity (PRA) and aldosterone (ALD) were significantly (p less than 0.01) increased by the exercise/heat stress, but were unaffected by erythrocythemia either 48 h or 9 d subsequent to reinfusion. PRA and ALD were correlated (r = 0.84, p less than 0.001) under all conditions. We concluded from this study that acutely induced erythrocythemia reduced the stress response to consecutive exercise/heat intervals as manifested in PC responses during HST 2.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗