scholarly journals Partitioning of body fluids and cardiovascular responses to circulatory hypovolaemia in the turtle, Pseudemys scripta elegans

1985 ◽  
Vol 116 (1) ◽  
pp. 237-250 ◽  
Author(s):  
A. W. Smits ◽  
M. M. Kozubowski
Keyword(s):  
Blood Volume ◽  
Cardiovascular Responses ◽  
Systemic Arterial Pressure ◽  
Body Fluids ◽  
The Body ◽  
Arterial Blood ◽  
Pseudemys Scripta ◽  
Fluid Transfer ◽  
Total Body ◽  
Tracer Dilution

Investigations were conducted (1) to measure the steady state compartmentation of body fluids and (2) to assess the efficacy of blood volume and pressure maintenance during haemorrhage-induced hypovolaemia in the pond turtle, Pseudemys scripta elegans. The pre-haemorrhage blood volume, as determined by tracer dilution of 51Cr-labelled erythrocytes, averaged 6.89 +/− 0.33% of the body mass, and was part of comparatively large extracellular (40.2 +/− 0.70%) and total body fluid volumes (75.25 +/− 1.48%). Turtles exhibited progressive reductions in systemic arterial pressure throughout a cumulative haemorrhage of −48% of their original blood volume, despite dramatic increases in heart rate and comparatively large magnitudes of transcapillary fluid transfer from interstitial to intravascular spaces. Arterial blood pressure returned to pre-haemorrhage values 2h after experimental haemorrhage ceased, concomitant with the restoration of the original blood volume. Our results support arguments made in previous studies that the resistance to fluid movement between vascular and extravascular locations in reptiles is comparatively low. Furthermore, the haemodynamic responses of turtles to experimental hypovolaemia suggest that barostasis through adjustments in vascular tone is less effective than that observed in other reptiles.

CO2 balance of a heterothermic rodent: comparison of sleep, torpor, and awake states

1984 ◽  
Vol 246 (1) ◽  
pp. R49-R55 ◽  
Author(s):  
P. E. Bickler
Keyword(s):  
Ground Squirrel ◽  
Lung Ventilation ◽  
Body Fluids ◽  
The Body ◽  
Metabolic Intensity ◽  
Co2 Balance ◽  
The Difference ◽  
Tb 32 ◽  
Total Body ◽  
Thermal States

CO2 homeostasis of different thermal states have been compared in a heterothermic ground squirrel, Spermophilus tereticaudus. Gas exchange (MO2, MCO2), lung ventilation (VE), and body temperature (Tb) were simultaneously measured during sleep, shallow torpor (Tb 25-29 degrees C), deep torpor (Tb 11-15 degrees C), awake heterothermia (Tb 30-42.5 degrees C), and transitions between these states. CO2 retention (falling MCO2/MO2 and VE/MCO2) accompanied entrance into sleep and torpor. CO2 retention lowered MO2 in sleeping and torpid squirrels beyond that caused by reduced Tb. In torpor at steady state, MCO2/MO2 (R) and ventilation returned to control values, and no further CO2 retention occurred. Arousal from sleep or torpor was accompanied by transiently high VE/MCO2 and R values as CO2 was released from the body fluids. R and VE/MCO2 values during heterothermia in awake squirrels (Tb 32-42.5 degrees C) showed that total body CO2 content remained unchanged until Tb reached 40 degrees C with onset of hyperventilation. Altered CO2 content of the body fluids is thus not a general feature of mammalian heterothermy. The difference in CO2 homeostasis of torpid and heterothermic awake animals may have implications for the difference in metabolic intensity of these states.

scholarly journals Cardiovascular responses to antigravity muscle loading during head-down tilt at rest and after dynamic exercises

2018 ◽  
Author(s):  
Cristiano Alessandro ◽  
Amirehsan Sarabadani Tafreshi ◽  
Robert Riener
Keyword(s):  
Muscle Activity ◽  
Human Subjects ◽  
Cardiovascular Responses ◽  
Bed Rest ◽  
Cardiovascular Regulation ◽  
Upright Position ◽  
The Body ◽  
Healthy Human ◽  
Arterial Blood ◽  
Muscle Loading

AbstractThe physiological processes underlying hemodynamic homeostasis can be modulated by muscle activity and gravitational loading. The effects of antigravity muscle activity on cardiovascular regulation has been observed during orthostatic stress. Here, we evaluated such effects during head-down tilt (HDT). In this posture, the gravitational gradient along the body is different than in upright position, leading to increased central blood volume and reduced venous pooling. We compared the cardiovascular signals obtained with and without antigravity muscle loading during HDT in healthy human subjects, both at rest and during recovery from leg-press exercises. Further, we compared such cardiovascular responses to those obtained during upright position. We found that loading the antigravity muscles during HDT at rest led to significantly higher values of arterial blood pressure than without muscle loading, and restored systolic values to those observed during upright posture. Maintaining muscle loading post-exercise altered the short-term cardiovascular responses, but not the values of the signals five minutes after the exercise. These results demonstrate that antigravity muscle activity modulates cardiovascular regulation during HDT. This modulation should therefore be considered when interpreting cardiovascular responses to conditions that affect both gravity loading and muscle activity, for example bed rest or microgravity.

BACK TO BASICS

1996 ◽  
Vol 17 (11) ◽  
pp. 395-403
Author(s):  
Nicholas Jospe ◽  
Gilbert Forbes
Keyword(s):  
Total Body Water ◽  
Extracellular Fluid ◽  
Body Fluids ◽  
Body Water ◽  
The Body ◽  
Electrolyte Balance ◽  
Electrolyte Disorders ◽  
Core Concepts ◽  
Body Fluid Volume ◽  
Total Body

Changes in volume and composition of body fluids due to disorders of fluid and electrolyte balance cause various common clinical illnesses. The rationale for reviewing the diagnosis and management of fluid and electrolyte disorders was eloquently denoted by Dr Altemeier, when he suggested that this knowledge belongs among the core concepts needed by the "keepers of the gates," that is, primary care pediatricians.1 In the body, homeostasis is maintained by the coordinated action of behavioral, hormonal, renal, and vascular adaptations to volume and osmotic changes. These core issues have been outlined in a previous article in this journal by Dr Hellerstein, and the current article proceeds from that discussion.2 Following introductory comments about body fluid volume and composition, we provide an overview of some of the etiologies of the disorders of volume, tonicity, and composition of body fluids and of the therapy to correct these disorders. Sodium, Osmolality, and the Volume of Body Fluids Total body water, which is 55% to 72% of body mass, varies with sex, age, and fat content and is distributed between the intracellular and extracellular spaces. The extracellular fluid (ECF), which comprises about one third of total body water, includes the intravascular plasma fluid and the extravascular interstitial fluid.

STUDIES IN EXPERIMENTAL HYPERTONICITY

PEDIATRICS ◽  
1962 ◽  
Vol 30 (2) ◽  
pp. 180-193
Author(s):  
Juan F. Sotos ◽  
Philip R. Dodge ◽  
Nathan B. Talbot
Keyword(s):  
Metabolic Acidosis ◽  
Sodium Chloride ◽  
Blood Volume ◽  
Intravenous Injection ◽  
Total Body Water ◽  
Cellular Metabolism ◽  
Body Fluids ◽  
Intracellular Water ◽  
Hydrogen Ion ◽  
Total Body

Hypertonicity of body fluids was induced in 23 rabbits by the intravenous injection of solutions of sodium chloride, sodium chloride and bicarbonate, sucrose, or urea at concentrations of about 2,000 mOsm/l. The results obtained suggest that (1) hypertonicity of body fluids can cause disturbances in cellular metabolism, resulting in the formation and release of large quantities of hydrogen ion and the development of severe extracellular metabolic acidosis; (2) with restoration of osmolality toward normal by rehydration, the acidosis is improved; and (3) there is no correlation between the values for plasma pH and the values for sodium and chlorides in plasma, total body water, extracellular and intracellular water, and blood volume.

Fluid and electrolyte physiology in anaesthetic practice

2017 ◽  
Author(s):  
Robert G. Hahn
Keyword(s):  
Blood Volume ◽  
Body Fluid ◽  
Extracellular Fluid ◽  
Haemorrhagic Shock ◽  
The Body ◽  
Intracellular Space ◽  
Fluid Compartment ◽  
Life Saving ◽  
Total Body ◽  
Infusion Fluid

The maintenance of body fluid homeostasis is an essential task in perioperative care. Body fluid volumes are tightly controlled by the nervous system, by hormones, and by the kidneys. All these systems are affected by anaesthesia and surgery in ways that must be appreciated by the anaesthetist. Administration of infusion fluids is the key tool to prevent major derangements of the body fluid volumes during before, during, and after surgery. By varying its composition, an infusion fluid can be made to selectively expand or shrink a body fluid compartment. The total osmolality determines whether the infused volume distributes over the total body water or over the extracellular fluid volume, or even attracts fluid from intracellular space. Infusion fluid is the first-line tool in the management of the vasodilation that is induced by both general and regional anaesthesia. Fluids are also an essential component in the treatment of haemorrhage, in which a reduction in arterial pressure implies that 20% of the blood volume has been lost. Capillary refill restores the blood volume, but too slowly to prevent haemorrhagic shock. In this situation, prompt intravenous fluid therapy is life-saving. Electrolyte derangements may be induced by disease and/or medication. The most essential ones to consider during anaesthesia are sodium, potassium, calcium, and bicarbonate.

Adrenergic, respiratory, and cardiovascular effects of core cooling in humans

1997 ◽  
Vol 272 (2) ◽  
pp. R557-R562 ◽  
Author(s):  
S. M. Frank ◽  
M. S. Higgins ◽  
L. A. Fleisher ◽  
J. V. Sitzmann ◽  
H. Raff ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Oxygen Consumption ◽  
Arterial Blood Pressure ◽  
Intravenous Infusion ◽  
Cardiovascular Responses ◽  
Arterial Blood ◽  
Norepinephrine Concentration ◽  
Total Body ◽  
Core Cooling ◽  
Total Body Oxygen

The adrenergic, respiratory, and cardiovascular responses to isolated core cooling were assessed in awake human subjects. Mild core hypothermia was induced by intravenous infusion of 30 or 40 ml/kg of cold saline (4 degrees C) on 2 separate days. A warm intravenous infusion (30 ml/kg, 37 degrees C) was given on a third day as a control treatment. Mean norepinephrine concentration increased 400% and total body oxygen consumption increased 30% when core temperature decreased 0.7 degrees C. Mean norepinephrine concentration increased 700% and total body oxygen consumption increased 112% when core temperature decreased 1.3 degrees C. Core cooling was associated with peripheral vasoconstriction and increased mean arterial blood pressure, whereas heart rate was unchanged. Plasma epinephrine and cortisol concentrations were unchanged during core cooling. There were no changes in any measured parameter with the warm infusion. These findings suggest that mild hypothermia induced by isolated core cooling is associated with an adrenergic response characterized by peripheral sympathetic nervous system activation without a significant adrenocortical or adrenomedullary response. The respiratory and cardiovascular responses to core cooling are characterized by a shivering-induced increase in metabolic rate, norepinephrine-mediated peripheral vasoconstriction, and increased arterial blood pressure.

Circulatory response to prolonged severe exercise

1964 ◽  
Vol 19 (5) ◽  
pp. 833-838 ◽  
Author(s):  
Bengt Saltin ◽  
Jesper Stenberg
Keyword(s):  
Blood Pressure ◽  
Cardiac Output ◽  
Oxygen Uptake ◽  
Stroke Volume ◽  
Arterial Blood Pressure ◽  
Blood Volume ◽  
Major Change ◽  
Work Load ◽  
The Body ◽  
Arterial Blood

Four subjects worked on a treadmill or a bicycle ergometer for 180 min at oxygen uptakes of 75% of the individual's max Vo2; after 90 min rest, the exercise was resumed and a maximal work load was tried. Repeated circulatory studies were made. The body weight decreased 3.1 kg (3.2–5.2%), but the reduction in blood volume was less than 5%. During submaximal exercise the major change in the hemodynamic response was a decrease in stroke volume (from 126 to 107 ml). Oxygen uptake and cardiac output increased slightly. There was a decrease of about 10% in systolic, diastolic, and mean arterial blood pressure during the 180 min of exercise. When the work was performed in a supine position there was the same reduction in the stroke volume as in the sitting work position. At the maximal work oxygen uptake, cardiac output, heart rate, and blood pressure attained almost normal values but there was a marked decrease in both work time and blood lactates. dehydration; blood volume; arterial blood pressure; circulatory reaction Submitted on January 31, 1964

VARIATIONS IN THE VOLUME AND CONCENTRATION OF THE BLOOD OF THE SNAIL, HELIX POMATIA L., IN RELATION TO THE WATER CONTENT OF THE BODY

1964 ◽  
Vol 42 (6) ◽  
pp. 1085-1097 ◽  
Author(s):  
R. F. Burton
Keyword(s):  
Water Content ◽  
Blood Volume ◽  
Total Body Water ◽  
Helix Pomatia ◽  
Dry Weight ◽  
Sodium Concentration ◽  
The Body ◽  
Albumen Gland ◽  
Snail Helix Pomatia ◽  
Total Body

A convenient measure of the "size" of a snail is its dry weight, exclusive of shell and albumen gland, and, where calculable, its blood solutes. The specimens of Helix pomatia studied contained between 3.8 and 10.2 g of Water per gram dry weight and between 51 and 456 mg of copper per kilogram dry weight. When "copper space" was defined as the weight of blood water that would contain the amount of copper present in the body, copper spaces varied between 1.1 and 4.4 g of water per gram dry weight. Variations in copper space (approximately equal to blood volume) accounted for the greater part of the variation in total body water, though the amount of water in the tissues was also variable. The concentration of sodium in the blood varied naturally over the range 46–129 mmole/kg of water, varying proportionately with chloride. Variations in sodium concentration are largely due to variations in the volume of blood in which the sodium is dissolved, but a given change in blood volume is, in general, associated with a proportionately smaller change in sodium concentration.

A Control-Oriented Model of Blood Volume Response to Hemorrhage and Fluid Resuscitation

2015 ◽  
Author(s):  
Ramin Bighamian ◽  
Andrew T. Reisner ◽  
Jin-Oh Hahn
Keyword(s):  
Blood Volume ◽  
Fluid Resuscitation ◽  
Closed Loop ◽  
The Body ◽  
Loop Control ◽  
Proposed Model ◽  
Volume Response ◽  
Proportional Integral Controller ◽  
Fluid Transfer ◽  
Using Data

This paper presents a control-oriented model of blood volume response to hemorrhage and fluid resuscitation that can be potentially utilized in closed-loop control of fluid resuscitation. A unique characteristic of the proposed model is that it is built to ensure structural parsimony while retaining physiological transparency. To accomplish this characteristic, blood volume regulation in the body to external perturbations of hemorrhage and fluid resuscitation was modeled as a low-order control system in which the fluid transfer between blood and interstitial fluid is governed by a proportional-integral controller. This in essence resulted in a minimal model with four parameters to be adapted to each individual. The validity of the proposed model was tested using data available in the literature. The results indicated that the proposed model was able to reproduce the blood volume response to hemorrhage and fluid resuscitation with high fidelity: on the average, the prediction error was only 1.53 ± 11.5 %, thus strongly supporting our claim that it can be used as viable basis for the design of closed-loop fluid resuscitation controllers.

Total body vascular capacitance changes during high intracranial pressure in dogs

1983 ◽  
Vol 245 (6) ◽  
pp. H947-H956 ◽  
Author(s):  
P. M. Stein ◽  
C. L. MacAnespie ◽  
C. F. Rothe
Keyword(s):  
Intracranial Pressure ◽  
Blood Volume ◽  
Right Atrium ◽  
Arterial Compliance ◽  
Mean Transit Time ◽  
Systemic Arterial Pressure ◽  
Response Threshold ◽  
Increased Intracranial Pressure ◽  
Total Body ◽  
The Right

The active capacitance response to increased intracranial pressure (Pic) was studied in nine chloralose-anesthetized dogs. The vena cavae were cannulated and drained into a reservoir as blood was pumped at a constant flow (Q) into the right atrium. Central blood volume was determined as Q times the mean transit time of dye from the right atrium to the aortic root. Arterial compliance (Ca) was determined from the monoexponential decay of systemic arterial pressure (SAP) during vagal cardiac arrest to compute changes in arterial volume (delta SAP X Ca). Atropine was administered to prevent bradycardia and dangerous, constant cardiac output-induced increases in pulmonary arterial (PAP) and right and left atrial pressures. Blood volume shifts indicative of active venoconstriction, included changes in reservoir, central, and arterial volumes during Pic of 100–200 mmHg. Raised Pic, after atropine, induced a tachycardia, increased systemic and pulmonary resistances, and increased SAP and PAP. Venoconstriction caused marked blood shifts between 125 and 200 mmHg Pic. The extrapolated response threshold was about 112 mmHg. In the most sensitive range, venoconstriction amounted to 3.9 ml X kg-1 per 25-mmHg change in Pic. These results indicate that intense active capacitance vessel constriction is an important part of cardiovascular hemostasis during rapidly increased intracranial pressure.

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