SEARCH · PubMed Health

Results for “BODY FLUID BALANCE”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 145 records · Page 8Linked to original sources

PubMed2004

Estrogen receptor-alpha expression in osmosensitive elements of the lamina terminalis: regulation by hypertonicity.

The subfornical organ (SFO), median preoptic nucleus (MnPO), and organum vasculosum lamina terminalis (OVLT), which are associated with the lamina terminalis, are important in the control of body fluid balance. Neurons in these regions express estrogen receptor (ER)-alpha, but whether the ER-alpha neurons are activated by hypertonicity and whether hypertonicity regulates ER-alpha expression are not known. Using fluorescent, double-label immunocytochemistry, we examined the expression of ER-alpha-immunoreactivity (ir) and Fos-ir in control and water-deprived male rats. In control animals, numerous ER-alpha-positive neurons were expressed in the periphery of the SFO, in both the dorsal and ventral MnPO, and in the dorsal cap of the OVLT. Fos-positive neurons were sparse in euhydrated rats but were numerous in the SFO, MnPO, and the dorsal cap of the OVLT after 48-h water deprivation. Most ER-alpha-ir neurons in these areas were positive for Fos, indicating a significant degree of colocalization. To examine the effect of dehydration on ER-alpha expression, animals with and without lesions surrounding the anterior and ventral portion of the 3rd ventricle (AV3V) were water deprived for 48 h. Water deprivation resulted in a moderate increase in ER-alpha-ir in the SFO of sham-lesioned rats (P = 0.03) and a dramatic elevation in AV3V-lesioned animals (P < 0.05). This was probably induced by the significant increase in plasma osmolality in both dehydrated groups (P < 0.001) rather than a decrease in blood volume, because hematocrit was significantly increased only in the dehydrated sham-lesioned animals. Thus these studies implicate the osmosensitive regions of the lamina terminalis as possible targets for sex steroid effects on body fluid homeostasis.

Animals↗

PubMed1996

Changes in maternal heart dimensions and plasma atrial natriuretic peptide levels in the early puerperium of normal and pre-eclamptic pregnancies.

OBJECTIVE: To measure plasma atrial natriuretic peptide (ANP) in relation to maternal haemodynamics and body fluid balance in the early puerperium following uncomplicated pregnancy and pre-eclampsia. DESIGN: A longitudinal study from late pregnancy and into the early postpartum period (days 1 to 3 and days 4 to 6) compared with nonpregnant controls. SUBJECTS: Eleven women with uncomplicated pregnancies, 12 women with pre-eclampsia and 12 healthy, nonpregnant women. MAIN OUTCOME MEASURES: Maternal heart dimensions determined by M-mode echocardiography, concentrations of ANP, and daily urine output and sodium excretion. RESULTS: After delivery increases in left atrial dimensions, represented as mean (SEM), from 33.2 (1.6) to 37.7 (1.7) mm and ANP levels from 7.9 (1.1) to 19.0 (2.7) pmol/L were observed at 1-3 days postpartum in normal pregnant women, but we were not able to demonstrate a significant increase in diuresis and natriuresis. In the third trimester left atrial dimensions (38.4 (1.2) mm) and ANP levels (15.4 (2.2) pmol/L) were greater in pre-eclampsia. ANP levels rose further in pre-eclamptic women in the early puerperium (27.4 (7.4) pmol/L) with an increase in diuresis and natriuresis, while left atrial dimensions did not change significantly (39.4 (1.7) mm). A pericardial effusion was found in 11 pre-eclamptic but in only three healthy pregnant women. CONCLUSIONS: A concommitant increase in left atrial dimensions and ANP in the early puerperium following uncomplicated pregnancies is consistent with the mechanism of atrial stretch as a stimulus for ANP release, although the biological significance of this finding remained unclear. A significantly higher release of ANP in the early puerperium after pregnancies complicated by pre-eclampsia may be a mechanism which promotes the renal elimination of excessive body fluids and sodium.

Adult↗

PubMed2004

Rats exhibit aldosterone-dependent sodium appetite during 24 h hindlimb unloading.

Hindlimb unloading (HU) is an animal model of microgravity and bed rest. In these studies, we examined the role of ingestive behaviours in regulating body fluid balance during 24 h HU. In the first experiment, all rats were given distilled water to drink while two groups were also given access to a sodium chloride solution (0.9% or 1.8%). Water and saline intakes were measured before, during and after 24 h of HU. Rats reduced water intake during 24 h HU in all conditions. During HU, rats increased their intakes of both saline solutions (0.9% NaCl (n= 11): control 7.8 +/- 3 ml; HU 18.2 +/- 4 ml; recovery 8.9 +/- 2.5 ml; 1.8% NaCl (n= 7): control 1.0 +/- 0.4 ml; HU 3.8 +/- 0.3 ml; recovery 1.2 +/- 0.5 ml). Although water intake decreased there was no reduction in total fluid intake when saline was available. Plasma volumes were reduced during HU compared to rats in a normal posture when only water was available to drink (control (n= 11) versus HU (n= 11): 4.0 +/- 0.2 versus 3.4 +/- 0.2 ml (100 g body weight)(-1)). When 0.9% saline was available in addition to water, plasma volumes after 24 h HU were not different from rats in a normal posture (control (n= 11) versus HU (n= 12): 4.3 +/- 0.4 versus 4.3 +/- 0.1 ml (100 g body weight)(-1)). Plasma aldosterone but not plasma renin activity was significantly elevated after 24 h HU. Central infusions of spironolactone blocked the increased intake of 1.8% saline that was associated with 24 h HU. Thus, HU results in an aldosterone-dependent sodium appetite and the ingestion of sodium may help maintain plasma volume.

Aldosterone↗

PubMed1999

Subacute effects of inspiratory resistive loading and head-out water immersion on pulmonary function.

Extrathoracic airways obstruction and scuba diving may induce pulmonary edema, probably because of increased hydrostatic transmural capillary pressure in the lung. This study was designed to examine the subacute pulmonary effects of the combined exposure to inspiratory resistive loading and immersion, as in scuba diving. Two groups each of eight healthy men were exposed to head-out water immersion in thermoneutral water for 40 min with or without an added inspiratory resistive load. At flows of 0.5 and 1.0 liter x s, the measured resistances were 4.4 and 9.0 hPa x s(-1) x liter(-1), respectively. Pulmonary function, including a flow-volume loop and transfer factor of the lung for carbon monoxide (Tlco, was measured before and 60 min after the end of the exposures. Body fluid balance was restored in the first 15 min after exposure, and Tlco was always corrected to a hemoglobin concentration of 146 g x liter(-1). There was a significant reduction in Tlco of 7.3+/-5.5% (P < 0.01) after the combined exposure to head-out water immersion and inspiratory resistive load. No changes in pulmonary function were seen after exposure to head-out water immersion or inspiratory resistive loading alone. The change in Tlco was normalized within 24 h. Submersion and resistance in breathing apparatus may contribute to the changes in pulmonary function seen immediately after dives. The nature of the exposure in these experiments and the time for recovery indicate that these changes are mechanically induced, and may not contribute to the long-term effects of diving on the lung.

Adult↗

PubMed1996

Adrenomedullin, a novel vasoactive hormone, binds to mouse astrocytes and stimulates cyclic AMP production.

We have examined the effects of adrenomedullin (AM), a novel hypotensive peptide first isolated from human pheochromocytoma, on receptor binding and cyclic AMP (cAMP) generation in primary cultures of mouse astrocytes. Competition binding studies showed that rat adrenomedullin (rAM) displaced the specific binding of [125I]rAM in a dose-dependent manner, with an estimated IC50 of 33 nM. Rat calcitonin gene-related peptide (rCGRP), which interacts with AM receptors in some vascular tissues, did not produce significant displacement of [125I]rAM at concentrations up to 3.3 microM. rAM stimulated cAMP production in mouse astrocytes in a dose-dependent manner, with an EC50 of 74 nM and a maximal stimulatory concentration of 1 microM. CGRP8-37, a CGRP receptor antagonist, failed to inhibit the cAMP response to rAM, although it attenuated CGRP-stimulated cAMP production. These data indicate that cultured mouse astrocytes possess specific AM receptors which are coupled to adenylate cyclase but do not interact with CGRP. AM may function as a neuropeptide and may play a role in the central regulation of blood pressure and body fluid balance.

Adrenomedullin↗

PubMed1991

Parabrachial nucleus projection towards the hypothalamic supraoptic nucleus: electrophysiological and anatomical observations in the rat.

It has been proposed that the pontine parabrachial nucleus (PBN) participates in the regulation of body fluid balance and the release of vasopressin from the neurohypophysis, although the pathways mediating the latter response are uncertain. This study in the rat, utilizing anatomical and electrophysiological methods, describes a projection from the lateral PBN towards the hypothalamic supraoptic nucleus (SON). Rats received iontophoretic injections of the anterograde tracer Phaseolus vulgaris leucoagglutinin (PHA-L, 2% solution). After 14-17 days, rats were sacrificed and their brains prepared for immunofluorescent visualization of projections to the SON region. PHA-L-labelled terminals were found primarily in perinuclear regions immediately dorsal to the SON. In contrast, injections within the medial PBN and the nearby Kölliker-Fuse nucleus did not reveal labelling in or around the SON. Extracellular recordings from 86 of 118 antidromically identified neurons in anaesthetized rats revealed a set of complex synaptic responses after stimulation in the PBN. Excitatory responses (in 82 of 86 cells) of short (less than 100 msec, 39/82 cells) and long (greater than 100 msec, 43/82) duration were observed in both vasopressin- and oxytocin-secreting cells of the SON, while 4/86 cells displayed a depressant response to PBN stimulation. In the adjacent perinuclear zone, 22/39 nonneurosecretory cells responded with an increase in their excitability consequent to an identical stimulus. These data suggest a predominantly facilitatory influence of lateral PBN neurons on SON neurosecretory cells in the rat, and that the PBN-SON projection is an indirect one that utilizes an interneuronal network located in the perinuclear zone adjacent to the SON.

Animals↗

PubMed2006

Contribution of comparative fish studies to general endocrinology: structure and function of some osmoregulatory hormones.

Fish endocrinologists are commonly motivated to pursue their research driven by their own interests in these aquatic animals. However, the data obtained in fish studies not only satisfy their own interests but often contribute more generally to the studies of other vertebrates, including mammals. The life of fishes is characterized by the aquatic habitat, which demands many physiological adjustments distinct from the terrestrial life. Among them, body fluid regulation is of particular importance as the body fluids are exposed to media of varying salinities only across the thin respiratory epithelia of the gills. Endocrine systems play pivotal roles in the homeostatic control of body fluid balance. Judging from the habitat-dependent control mechanisms, some osmoregulatory hormones of fish should have undergone functional and molecular evolution during the ecological transition to the terrestrial life. In fact, water-regulating hormones such as vasopressin are essential for survival on the land, whereas ion-regulating hormones such as natriuretic peptides, guanylins and adrenomedullins are diversified and exhibit more critical functions in aquatic species. In this short review, we introduce some examples illustrating how comparative fish studies contribute to general endocrinology by taking advantage of such differences between fishes and tetrapods. In a functional context, fish studies often afford a deeper understanding of the essential actions of a hormone across vertebrate taxa. Using the natriuretic peptide family as an example, we suggest that more functional studies on fishes will bring similar rewards of understanding. At the molecular level, recent establishment of genome databases in fishes and mammals brings clues to the evolutionary history of hormone molecules via a comparative genomic approach. Because of the functional and molecular diversification of ion-regulating hormones in fishes, this approach sometimes leads to the discovery of new hormones in tetrapods as exemplified by adrenomedullin 2.

Adrenomedullin↗

PubMed2001

Activation of serotonergic pathways from the midbrain raphe system to the subfornical organ by hemorrhage in the rat.

The role of serotonergic neural pathways from the midbrain raphe nuclei to the subfornical organ (SFO) in the central regulation of cardiovascular function and body fluid balance was investigated in adult male rats under urethane anesthesia. Eleven neurons in the dorsal raphe nucleus (DR) were antidromically activated by electrical stimulation of the SFO. Of these neurons, 6 displayed an excitatory response following hemorrhage (10 ml/kg bwt) while the remaining 5 neurons were unresponsive. Ninety-four neurons in the SFO were tested for a response to electrical stimulation of the DR or hemorrhage. Electrical stimulation of the DR caused orthodromic excitation (19%) or inhibition (5%) of the activity of SFO neurons. In 14 of 18 SFO neurons that displayed the excitation to the stimulation of the DR, hemorrhage (30 to 50 mm Hg suppression in mean arterial pressure) produced an increase of their discharge, while the stimulus was without effect in the remaining neurons responsive to the stimulation of the DR. The effects of hemorrhage on serotonin (5-HT) release in the region of the SFO were examined using intracerebral microdialysis techniques. Hemorrhage significantly increased 5-HT and its metabolite 5-hydroxyindoleacetic acid (5-HIAA) concentrations in the region of the SFO. The present data suggest that the serotonergic pathways from the DR to the SFO may relay activation of the peripheral baroreceptors to SFO neurons which result in enhanced excitability, indicating the involvement of the pathways in the regulation of cardiovascular function.

Action Potentials↗

PubMed1993

Renal response to head-out water immersion in Korean women divers.

Head-out water immersion (HOI) induces a profound diuresis and natriuresis, which may endanger the body fluid balance of breath-hold divers during prolonged diving work. To investigate if adaptation is acquired by professional breath-hold divers, we have evaluated renal responses to 3-h HOI in 5 Korean women divers (Amas) and 11 nondiving housewives (controls). In both control and diver groups, the average urine flow during 3-h immersion was four times greater and Na+ excretion was 70%-80% greater than the pre-immersion value [urine flow: 3.7 (SD 1.0) ml.min-1 vs 0.9 (SD 0.4), P < 0.001, in controls; 4.3 (SD 0.9) vs 1.1 (SD 0.4), P < 0.001, in divers; Na+ excretion: 270 (SD 176) mumol.min-1 vs 161 (SD 84), P < 0.025, in controls; 303 (SD 31) vs 164 (SD 62), P < 0.005, in divers]. In all cases, the values for a given period were not significantly different between the two groups. The plasma concentrations of Na+ and osmolality, and renal clearance of creatinine did not change significantly. However, the osmolal clearance increased [from 2.0 (SD 0.8) ml.min-1 to 2.8 (SD 0.7), P < 0.05, in the controls; from 2.2 (SD 0.4) to 2.6 (SD 0.4), P < 0.05, in the divers] and free water clearance changed from negative to positive values [from -1.1 (SD 0.5) ml.min-1 to 1.2 (SD 0.3), P < 0.005, in the controls; from -1.2 (SD 0.4) to 1.6 (SD 1.1), P < 0.01, in the divers] during immersion, again the pattern of change being similar in the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed2000

Effects of a phosphodiesterase III inhibitor on circulating blood volume after cardiopulmonary bypass.

Using a new method based on pulse dye densitometry, circulating blood volume (BV) was measured without direct sampling in patients undergoing open-heart surgery, and the effects of phosphodiesterase (PDE) III inhibitor administration during cardiopulmonary bypass (CPB) were evaluated. Sixteen patients scheduled for elective coronary artery bypass grafting were randomly assigned to the PDE III inhibitor group or control group. BV was determined before CPB, and immediately, and 4 and 12h after operation. After declamping of the aorta, the PDE III inhibitor amrinone (1 mg/kg) was infused as a single bolus into the venous reservoir in the PDE III inhibitor group. BV decreased significantly soon after the operation in the control group. It did not decrease in the PDE III inhibitor group (48.6 +/- 44 and 60.6 +/- 8.0 ml/kg for the control and PDE III inhibitor groups. respectively). Four hours after surgery and beyond no significant changes in BV were observed in either group. The body fluid balance was negative in both groups. In conclusion, a single administration of PDE III inhibitor during CPB was found to sustain BV soon after operation and, therefore, is useful for postoperative management of open-heart surgery.

Aged↗

PubMed1981

Polydipsia and abolition of angiotensin-induced drinking after transections of subfornical organ efferent projections in the rat.

Rats with transections of subfornical organ (SFO) efferent projections failed to drink to intravenous angiotensin-II (AII) but responded to intracellular dehydration and water deprivation and suppressed drinking when food deprived. However, the transected rats were polydipsic and polyuric. Thus SFO efferent projections mediate AII-induced drinking and may be involved in the regulation of body fluid balance.

Angiotensin II↗

PubMed1986

Long-term effects of lesions of the tissue surrounding the preoptic recess on paraventricular nuclei in rats.

In this investigation we have observed the effects of withholding water for 5 days, the effects of long-term (5 weeks) lesions of the tissue surrounding the preoptic recess in the anteroventral third ventricle (AV3V region), and the interaction of the effects of long-term AV3V lesions and water deprivation on paraventricular nuclei. The purpose of these observations was to see if recovery of the antidiuretic response after AV3V lesions is associated with recovery of fine structural responses in these neurosecretory cells. Paraventricular neurosecretory cells of rats deprived of water for 5 days were hypertrophied in controls and in rats with AV3V lesions. Areas of cell bodies and their nuclei were increased, as were the number of Golgi stacks and electron dense (immature) neurosecretory granules. A greater percentage of nucleoli were adjacent to the nuclear envelope. Paraventricular neurons of rats with AV3V lesions also had fine structural changes characteristic of increased secretory activity, even in animals with free access to drinking water. The areas of cells and their nucleoli in coronal sections, and the number of Golgi stacks and electron-dense neurosecretory granules per cell were significantly increased in both treatment groups with AV3V lesions. There was a greater increase in the numbers of Golgi stacks and immature neurosecretory granules tended to be more numerous in water-deprived lesioned rats than in water-deprived controls. We suggest that recovery of body fluid balance in rats with chronic AV3V lesions involves enhanced secretory activity of neurosecretory cells in paraventricular nuclei, possibly stimulated via undamaged descending connections from the subfornical organ and by ascending pathways activated by cardiovascular volume receptors.

Adaptation, Physiological↗

PubMed1996

Arcuate nucleus inputs onto subfornical organ neurons that respond to plasma hypernatremia and angiotensin II.

Experiments were done in urethane anesthetized rats to investigate the effect of electrical and glutamate stimulation of arcuate nucleus (Arc) on the discharge rate of subfornical organ (SFO) neurons that responded to either plasma hypernatremia or angiotensin II (ANG II). Extracellular recordings were made from 253 histologically verified single neurons in SFO. Of these, 40.3% (102/253) responded with excitation and 10% (25/253) with inhibition to Arc stimulation. Thirty-five (34.3%) of the units excited by Arc were also excited by intracarotid infusion of hypertonic (0.5 M) NaCl. In addition, 37 (36.3%) of the units excited by Arc were also excited by intracarotid infusion of ANG II. Furthermore, 10 (40.0%) of the units inhibited by Arc were found to be excited by ANG II. None of the units inhibited by Arc stimulation were responsive to plasma hypernatremia. These data indicate that inputs from Arc neurons converge onto SFO neurons that alter their discharge rate during changes in plasma concentration of Na+ or ANG II. These results suggest that Arc may be involved in body fluid balance and circulatory regulation by modulating the activity of SFO neurons that function in the detection of blood-borne signals from the depletion of intra- and extra-cellular fluid volumes.

Angiotensin II↗

PubMed1996

Changes in NADPH diaphorase activity in forebrain structures of the laminae terminalis after chronic dehydration.

The effect of 3-day chronic dehydration on nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-diaphorase) histochemical staining in forebrain circumventricular structures was investigated in the rat. Increased number and/or intensity of staining of NADPH-diaphorase positive neurons was observed in subfornical organ, organum vasculosum of the laminae terminalis, and median preoptic nucleus. In addition, dense punctate NADPH-diaphorase reaction product was found throughout the internal portion of median eminence. These data suggest the involvement of nitric oxide synthase producing neurons in homeostatic mechanisms controlling body fluid balance and the circulation.

Animals↗

PubMed1976

Schedule-induced polydipsia: the role of oral and plasma factors.

To appreciate the contribution of oral and post-absorptive factors in the control of schedule-induced polydipsia (SIP), body fluid balance was determined at various times into the 4 hr session. Although dehydrated at the start of the session, rats quickly returned to normal balance which was maintained, despite excessive intake, by a brisk water diuresis. Plasma, as measured via the T-1824 technique, was also normal. Gastric infusion of water following each pellet delivery failed to eliminate the polydipsia despite marked hemodilution, whereas, oral infusion of equivalent amounts of water completely abolished the phenomenon. Taken together, these results suggest that SIP is mediated by oropharyngeal rather than hydration controls.

Animals↗

PubMed1988

Osmotic and hypovolemic thirst in spontaneously hypertensive rats.

Osmotic- and hypovolemic-induced water intake as well as urinary excretion of sodium and other solutes were compared in spontaneously hypertensive (SHR) and normotensive Wistar (NWR) rats. No significant differences were found between SHR and NWR in water intake and urinary excretion under conditions of euhydration and in response to 24 hr water deprivation. Administration of osmotic load (0.5 ml.100 g-1 body weight of 10% NaCl IV) elicited: (1) higher intake of water (by 1.77 +/- 0.60 ml.100 g-1 body weight), (2) lower urinary excretion of sodium and other solutes, and (3) greater retention of fluid in SHR than in NWR. Reduction of blood volume by amount equivalent to 1.8% of body weight decreased arterial blood pressure by 31.9 +/- 3.5 and 10.8 +/- 1.7 mmHg in SHR and NWR, respectively. In spite of significantly greater hypotension, bleeding elicited in SHR smaller elevation of water intake than in NWR (1.39 +/- 0.25 vs. 2.14 +/- 0.49 ml.100 g-1 body weight). The data provide evidence for existence of significant differences in the control of body fluid balance between SHR and NWR. It is suggested that hyperdipsia elicited by administration of the hyperosmotic load in SHR does not result from primary hyperresponsiveness of the thirst system to osmotic/sodium stimulation but is rather secondary to osmotic load retention.

Animals↗

PubMed1991

Altered acceptability of and preference for sugar solutions by diabetic rats is normalized by high-fat diet.

Two experiments examined the ingestive responses of streptozotocin-diabetic rats fed low-fat or high-fat diets to glucose, fructose, sucrose and maltose solutions in brief (30 min) intake tests. In Experiment 1, one-bottle acceptability tests were used whereas two-bottle preference tests were used in Experiment 2. Three main findings resulted from these studies. Firstly, diabetic rats fed the low-fat diet displayed a reduced acceptance of and preference for all concentrated sugar solutions. Secondly, glucose consumption patterns of diabetic rats fed the low-fat diet were distinctly different from their responses to the other sugars. Thirdly feeding high-fat diets, either high or low in carbohydrate, normalized the responses of diabetic rats to the sugar solutions. The results suggest that feeding high-fat diets to diabetic rats normalizes their responses to sugar solutions because of reductions in hunger and thirst associated with the provision of a utilizable source of calories and an improvement in body fluid balance.

Analysis of Variance↗

PubMed2004

GABA-mediated attenuation of noradrenaline release in the rat median preoptic area caused by intravenous injection of metaraminol.

Previous studies have shown that the noradrenergic system in the median preoptic nucleus (MnPO) play an important role in the control of the body fluid balance and cardiovascular function and that the release of noradrenaline in the MnPO is regulated by gamma-aminobutyric acid (GABA) receptor mechanisms. The present study was carried out to examine whether the GABAergic system is involved in the modulation of the noradrenaline release in the MnPO in response to an elevation in blood pressure using in vivo microdialysis techniques. In urethane-anaesthetised male rats, the rise in arterial pressure caused by intravenous administration of the alpha-agonist metaraminol significantly decreased dialysate noradrenaline concentration in the MnPO area. The decrease in the noradrenaline level elicited by the metaraminol administration was significantly attenuated by perfusion with either bicuculline (10 microM), a GABA(A) receptor antagonist, or phaclofen (10 microM), a GABA(B) receptor antagonist, through a microdialysis probe. The amount of the antagonist-induced attenuation was much greater in the bicuculline-treated group than in the phaclofen-treated group. These results suggest that the release of noradrenaline in the MnPO area may be modulated by neural inputs from the peripheral baroreceptors, and that the neural inputs may be mediated in part through GABA(A) receptors rather than GABA(B) receptors in the MnPO area.

Adrenergic alpha-Agonists↗