The Physiological Regulation of Thirst and Fluid Intake

Thirst is important for maintaining body fluid homeostasis and may arise from deficits in either intracellular or extracellular fluid volume. Neural signals arising from osmotic and hormonal influences on the lamina terminalis may be integrated within the brain, with afferent information relayed from intrathoracic baroreceptors via the hindbrain to generate thirst.

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Physiological regulation of the renal vasopressin receptor-effector pathway in dogs

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1990.258.3.r763 ◽

1990 ◽

Vol 258 (3) ◽

pp. R763-R769

Author(s):

L. B. Kinter ◽

N. Caldwell ◽

S. Caltabiano ◽

C. Winslow ◽

D. P. Brooks ◽

...

Keyword(s):

Volume Expansion ◽

Body Fluid ◽

Physiological State ◽

Extracellular Volume ◽

Conscious Dogs ◽

Physiological Regulation ◽

Fluid Homeostasis ◽

Effector Pathway ◽

Body Fluid Homeostasis ◽

V2 Receptor

Physiological regulation of receptor-effector pathways is recognized as a significant factor determining target organ selectivity and sensitivity in several hormonal systems. Whether or not physiological regulation of the renal vasopressin (V2) receptor-effector pathway participates in the control of body fluid homeostasis is unknown. We evaluated four states likely to be associated with altered sensitivities of the renal V2 receptor-effector pathway as follows: dehydration (18-h hydropenia), volume expansion, exogenous arginine vasopressin (AVP) infusion (10 ng/kg + 0.25 ng.kg-1.h-1), and cyclooxygenase blockade (indomethacin, 2 mg/kg + 2 mg.kg-1.h-1) for effects on the antidiuretic efficacies and potencies of putative V2-receptor antagonists in conscious dogs. The antidiuretic efficacies of desGly9[Pmp1-D-Tyr(Et)2Val4]AVP [Smith Kline & French (SK&F) 101926; 0.01-1,000 micrograms/kg] ranged from that of a full agonist to that of an antagonist, depending on the physiological state studied. The vasopressin antagonist potency of SK&F 101926 was increased 150-fold in association with extracellular volume expansion and decreased by blockade of renal cyclooxygenase activity. This spectrum of activities is that anticipated for a partial agonist under conditions where receptor number and/or sensitivity of receptor-effector coupling is increased or decreased, respectively. Thus volume expansion and increased circulating vasopressin concentration are associated with effective decreases, whereas hydropenia and cyclooxygenase blockade are associated with effective increases in sensitivity of the renal V2 receptor-effector pathway in the dog kidney. We conclude that the V2 receptor-effector pathway is a site of integration of physiological mechanisms participating in the control of body fluid homeostasis in conscious dogs.

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Dialysate Dumping: A Novel Cause of Inadequate Dialysis in Continuous Ambulatory Peritoneal Dialysis (CAPD) Patients

Peritoneal Dialysis International ◽

10.1177/089686088900900418 ◽

1989 ◽

Vol 9 (4) ◽

pp. 319-320 ◽

Cited By ~ 13

Author(s):

Ralph J. Caruana ◽

Kenneth L. Smith ◽

Charlene P. Hess ◽

John Charles Perez ◽

Patricia L. Cheek

Keyword(s):

Peritoneal Dialysis ◽

Continuous Ambulatory Peritoneal Dialysis ◽

Fluid Intake ◽

Extracellular Fluid ◽

Abdominal Discomfort ◽

Fluid Volume ◽

Extracellular Fluid Volume ◽

Substantial Portion

Inadequate control of serum chemistries and extracellular fluid volume may result in patients being changed from continuous ambulatory peritoneal dialysis (CAPD) to another form of dialysis. We report 2 patients in whom apparent inadequacy of CAPD resulted from dialysate dumping. The first patient could not control her fluid intake and required frequent hypertonic exchanges. She felt too full with these exchanges and drained a substantial portion of each exchange 30 to 60 min after infusion. Patient 2 had similar complaints but simply drained a large portion of each fresh bag directly into the drain bag at the start of the fiush-before-fill step. Both patients had improved results from CAPD once they stopped their dialysate dumping. Partial wasting of each exchange because of abdominal discomfort should be added to the causes of inadequate dialysis in CAPD.

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Urinary system

Oxford Handbook of Medical Sciences ◽

10.1093/med/9780198789895.003.0007 ◽

2021 ◽

pp. 497-534

Keyword(s):

Body Fluid ◽

Obstructive Uropathy ◽

Extracellular Fluid ◽

Mechanisms Of Action ◽

Urinary Continence ◽

Renal Tubules ◽

Urinary System ◽

Bladder Control ◽

System P ◽

Body Fluid Homeostasis

The ‘Urinary system’ chapter opens with a description of the urinary tract morphology (kidney, ureters, bladder) and its histology. Renal function is considered, including glomerular filtration, the role and regulation of the renal tubules in producing dilute and concentrated urines, and the mechanisms of action of diuretic drugs. The function of the kidney in body fluid homeostasis (extracellular fluid volume and osmolarity, pH) is then discussed, and the regulation of kidney function explored, including bladder control and urinary continence. Finally, renal failure and obstructive uropathy are discussed as examples of renal pathology.

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A Hard Scientific Quest: Understanding Voluntary Movements

Daedalus ◽

10.1162/daed_a_00324 ◽

2015 ◽

Vol 144 (1) ◽

pp. 83-95 ◽

Cited By ~ 11

Author(s):

Emilio Bizzi ◽

Robert Ajemian

Keyword(s):

Spinal Cord ◽

Voluntary Movements ◽

Functional Modules ◽

Neural Signals ◽

Afferent Information ◽

The Central Nervous System ◽

Pattern Formations ◽

The Many ◽

Scientific Quest ◽

The Brain

In this article we explore the complexities of what goes on in the brain when one wishes to perform even the simplest everyday movements. In doing so, we describe experiments indicating that the spinal cord interneurons are organized in functional modules and that each module activates a distinct set of muscles. Through these modules the central nervous system has found a simple solution to controlling the large number of muscle fibers active even during the execution of the simplest action. We also explore the many different neural signals that contribute to pattern formations, including afferent information from the limbs and information of motor memories.

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Some biochemical and physiological features of normal monkeys (Macaca radiata)

Journal of Applied Physiology ◽

10.1152/jappl.1963.18.6.1231 ◽

1963 ◽

Vol 18 (6) ◽

pp. 1231-1233 ◽

Cited By ~ 4

Author(s):

S. G. Srikantia ◽

C. Gopalan

Keyword(s):

Total Body Water ◽

Body Fluid ◽

Extracellular Fluid ◽

Body Water ◽

Fluid Volume ◽

Extracellular Fluid Volume ◽

Sodium Thiocyanate ◽

Macaca Radiata ◽

Hematological Indices ◽

Total Body

Determinations of body-fluid spaces with antipyrine for total-body water and sodium thiocyanate for extracellular fluid volume, hematological indices, and several serum constituents in about 500 Macaca radiata monkeys revealed that most of the values obtained were very similar to values obtained in man. body fluid spaces; hematology Submitted on April 22, 1963

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The Hyponatremia of Exercise

International Journal of Sport Nutrition ◽

10.1123/ijsn.2.3.205 ◽

1992 ◽

Vol 2 (3) ◽

pp. 205-228 ◽

Cited By ~ 56

Author(s):

Timothy D. Noakes

Keyword(s):

Sodium Chloride ◽

Fluid Intake ◽

Third Space ◽

Extracellular Fluid ◽

Fluid Retention ◽

Fluid Volume ◽

Extracellular Fluid Volume ◽

Cerebral Function ◽

Competitive Athletes ◽

Space Effect

The hyponatremia of exercise may exist in symptomatic and asymptomatic forms. Symptomatic hyponatremia is usually characterized by severe alterations in cerebral function including coma and grand ma1 seizures; it develops especially in less competitive athletes who have maintained high rates of fluid intake during endurance events lasting at least 5 hours. The hyponatremia becomes symptomatic when the volume of excess fluid retained exceeds 2 to 3 liters. The etiology of the condition is unknown. Possibly as many as three or more pathologies (abnormal fluid retention possibly due to inappropriate ADH secretion, abnormal regulation of the extracellular fluid volume, translocation of sodium into a "third space") must be present for symptomatic hyponatremia to develop. The avoidance of overhydration would appear to be the only certain way that susceptible individuals can prevent symptomatic hyponatremia. Sodium chloride containing solutions ingested in physiologically significant concentrations would likely prevent a possible "third space" effect.

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Accessory lymph sacs and body fluid partitioning in the lizard, Sauromalus hispidus

Journal of Experimental Biology ◽

10.1242/jeb.121.1.165 ◽

1986 ◽

Vol 121 (1) ◽

pp. 165-177

Author(s):

A. W. Smits

Keyword(s):

Protein Content ◽

Body Mass ◽

Total Protein ◽

Body Fluid ◽

Extracellular Fluid ◽

Body Fluids ◽

Body Water ◽

Extracellular Fluid Volume ◽

Total Protein Content ◽

Fluid Shifts

Chuckwalla lizards (genus Sauromalus) may accumulate substantial quantities of body fluid in extracoelomic, lateral abdominal spaces called accessory lymph sacs. The lymph sac fluid (LSF) of S. hispidus is similar to that of serum in Na+, K+ and Cl- concentrations, but the total protein content (3.58 +/− 0.20 g dl-1) is only half that measured in serum (7.05 +/− 0.26 g dl-1). These analyses confirm that LSF is an extravascular form of extracellular fluid, similar in composition to true lymph. Measurements of body fluid partitioning by dilution analysis indicate that Sauromalus hispidus Stejnejer possesses a comparatively large (38.9% body mass) and labile extracellular fluid volume (ECFV), and that the volume of LSF is dependent on the ECFV. Expansion of the ECFV (and subsequent accumulation of LSF) is observed following large, intercompartmental fluid shifts from intracellular to extracellular locations when lizards are kept inactive in simulated hibernation, are injected with KCl in amounts similar to those found in their field diet, and are hydrated with NaCl that is isotonic to their body fluids. These data collectively suggest that the lymph sacs of chuckwallas facilitate expansion of the ECFV, and may be adaptive not only as a means to store body water, but to accommodate transient shifts in body fluid from intracellular to extracellular locations.

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