Effects of intracerebroventricular administration of atrial natriuretic peptide (ANP) on blood pressure, heart rate and plasma ADH and corticosterone levels in normal and dehydrated rabbits

Kallaras, C.; Angelopoulos, Nicholas; Apostolakis, M.; Bountzioukas, S; Guiba-Tziampiri, Olympia; Kontoleon-Vakalopoulou, H.; Mavroudis, K.

doi:10.1007/bf03347304

Cited by 6 publications

(2 citation statements)

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“…In diarrhea, dehydration is essentially caused by the latter, whereas thirst usually is maintained or increased. In the current study, we selected the simplest model of dehydration by simply withholding water (23,24). In fact, there is no simple model for the dehydration caused by diarrhea.…”

Section: Discussionmentioning

confidence: 99%

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Water and Electrolyte Salvage in an Animal Model of Dehydration and Malnutrition

Islam,

Abély,

Alam

et al. 2004

J. pediatr. gastroenterol. nutr.

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Background and aimRecently, a new oral rehydration solution (ORS) called Resomal has been designed specifically for children with severe malnutrition. The aim of this study was to assess the effect of malnutrition on renal and intestinal responses to dehydration, and to compare intestinal water and electrolyte absorption from Resomal and from the standard World Health Organization‐Oral Rehydration Solution (WHO‐ORS).MethodsMalnutrition was achieved in a rabbit model by feeding the animals daily for 30 days with half the amount of food that a well‐nourished group of control animals had consumed on the previous day. Dehydration was achieved by water deprivation for 46 hours in both control and malnourished rabbits. At 46 hours, dehydration was assessed by changes in body weight, urinary volume and osmolarity, and blood urea nitrogen concentration. At that time active colonic and jejunal mucosal electrolyte transport in Ussing chambers was also measured. Small intestinal absorption of water, sodium, and potassium was measured in vivo during intestinal perfusion of the two ORSs and in vitro by measurement of mucosal electrogenic glucose‐stimulated sodium absorption across intestinal patches.ResultsCompared to controls (C), well‐nourished but dehydrated (C+D) animals lost 12% of their body weight, with an 87% reduction in urine volume, a 110% increase in urine osmolality, and a 94% increase in blood urea nitrogen. In the colon of C+D animals, short‐circuit current (Isc) and net sodium transepithelial flux (JNa+ net) were increased. Almost identical results were obtained in malnourished and dehydrated (M+D) animals. In the jejunum, net in vivo absorption of water (JWater), sodium (JNa+), and potassium (JK+) were increased during standard ORS infusion in both dehydrated groups. During Resomal infusion, water absorption was the same as seen with WHO‐ORS, but sodium absorption was reduced, and potassium absorption was increased in both well‐nourished and malnourished dehydrated animals. In vitro, compared to controls, the glucose‐stimulated short‐circuit current (ΔIsc), JNa+ net and G were increased in both dehydrated groups.ConclusionDuring experimental dehydration, the kidney and large intestine salvage water and electrolytes, thus reducing the consequences of dehydration. These findings indicate that jejunal water absorption from Resomal and WHO‐ORS is increased during dehydration, but Resomal allows for less sodium and more potassium to be absorbed, both in well‐nourished and malnourished dehydrated rabbits.

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Section: Discussionmentioning

confidence: 99%

“…The rabbits were dehydrated (D) by withholding water for 46 hours while they were maintained on their assigned diet (23,24). The control group (C) continued to receive both food and water ad libitum.…”

Section: Development Of Dehydration By Water Deprivationmentioning

confidence: 99%

Water and Electrolyte Salvage in an Animal Model of Dehydration and Malnutrition

Islam,

Abély,

Alam

et al. 2004

J. pediatr. gastroenterol. nutr.

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Intracerebroventricular administration of atrial natriuretic peptide prevents increase of plasma ADH, aldosterone and corticosterone levels in restrained conscious dehydrated rabbits

Kallaras

Angelopoulos

Bountzioukas

et al. 2004

J Endocrinol Invest

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In order to investigate the effects of centrally administered ANP on plasma ADH, aldosterone and corticosterone levels as well as on blood pressure and on heart rate, 20 male New Zealand White (NZW) rabbits were used. Measurements were made on restrained conscious animals one week after the implantation of an indwelling intracerebroventricular (icv) cannula and two indwelling intravascular catheters (intracarotid and intrajugular). Animals were classified into two main groups, those with water available ad libitum ("euhydrated" group) and those who were dehydrated for 24 h ("dehydrated" group) before blood pressure and heart rate recordings and blood sampling for hormonal determination. Each group's individuals were divided into two subgroups of five animals each. Blood samples were collected at 0 min (control) and 30, 60, 90, 120 min following icv administration of 25 microl of either artificial cerebrospinal fluid (aCSF) (subgroups "aCSF") or human (h) ANP (1 microg) in aCSF (25 microl) (subgroups "hANP"). Blood pressure and heart rate were also recorded at the same times. Plasma ADH, aldosterone and corticosterone concentrations were determined using RIA. The results were analysed by analysis of variance (ANOVA). Blood pressure and heart rate values were unaffected by water deprivation or by ANP administration. Mean plasma corticosterone levels at all times (30-120 min) were significantly higher (p<0.001) than those at 0 min time. Plasma corticosterone levels in the "dehydrated+aCSF" group were significantly higher (p<0.05) than in each of the other groups ("dehydrated+hANP", "euhydrated+aCSF", "euhydrated+hANP"). Plasma corticosterone levels in each of those other groups did not differ significantly from one another. Dehydration resulted in a tendency to increase in aldosterone levels (p<0.07), and icv administration of hANP tended (p<0.08) to prevent in the "dehydrated+hANP" experimental group the increase in aldosterone levels observed in the control "dehydrated+aCSF" group from 30 to 120 min. Dehydration resulted in an increase in ADH levels (p<0.0001), and icv administration of hANP prevented (p<0.05) in "dehydrated+hANP" experimental group the increase in ADH levels observed in the control "dehydrated+aCSF" group from 90 to 120 min. The increase of corticosterone and ADH and the tendency towards increase in aldosterone in the control dehydrated groups could possibly be due to the combined stress stimulus of dehydration and restriction in the restrain box. These results indicate that centrally administered ANP, at the concentration achieved in the present study, neither affects blood pressure and heart rate in conscious restrained euhydrated and 24 h-dehydrated NZW rabbits nor decreases the ADH, aldosterone and corticosterone response to dehydration, but does apparently modulate ADH, aldosterone and corticosterone responses to other stimuli in the dehydrated state. In conclusion, the results of this study confirm that brain ANP may have an inhibitory effect on stimulated ADH, aldosterone and corticosteron...

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Physiological regulation of brain angiotensin receptor mRNA in AT1a deficient mice

Rocha

Chen

Oliveira

et al. 2005

Experimental Neurology

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Effects of intracerebroventricular administration of atrial natriuretic peptide (ANP) on blood pressure, heart rate and plasma ADH and corticosterone levels in normal and dehydrated rabbits

Cited by 6 publications

References 69 publications

Water and Electrolyte Salvage in an Animal Model of Dehydration and Malnutrition

Water and Electrolyte Salvage in an Animal Model of Dehydration and Malnutrition

Intracerebroventricular administration of atrial natriuretic peptide prevents increase of plasma ADH, aldosterone and corticosterone levels in restrained conscious dehydrated rabbits

Physiological regulation of brain angiotensin receptor mRNA in AT1a deficient mice

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