Hypothalamic Knife Cuts Alter Fluid Regulation, Vasopressin Secretion, and Natriuresis during Water Deprivation

1983 ◽  
Vol 36 (5) ◽  
pp. 364-370 ◽  
Author(s):  
Steven L. Bealer ◽  
Joan T. Crofton ◽  
Leonard Share
1991 ◽  
Vol 81 (s25) ◽  
pp. 471-476 ◽  
Author(s):  
Felix Vargas ◽  
Maria J. Baz ◽  
Juan de D. Luna ◽  
Jesus Andrade ◽  
Esteban Jodar ◽  
...  

1. Urinary excretion of digoxin-like immunoreactive factor and arginine-vasopressin and other parameters related to salt and water metabolism were studied in hyper- and hypo-thyroid rats after different tests. 2. Urinary excretion of arginine-vasopressin was increased in hyperthyroid and reduced in hypothyroid rats with respect to controls, in response to water deprivation or a hypertonic saline load. 3. Control and hypothyroid rats showed the highest urinary excretion of digoxin-like immunoreactive factor after a hypertonic saline load. However, hyperthyroid rats had the highest urinary levels of digoxin-like immunoreactive factor under normal conditions. 4. From these results it is suggested that: (a) hyper- and hypo-thyroid rats exhibit hyper- and hypo-responsiveness of arginine-vasopressin secretion to osmotic stimuli, respectively; (b) an unidentified digoxin-like immunoreactive factor measured in unextracted rat urine may be related to diuresis and natriuresis in control and hypothyroid rats; however, dissociation between this factor and natriuresis is observed in hyperthyroid rats.


1981 ◽  
Vol 240 (4) ◽  
pp. E394-E401 ◽  
Author(s):  
T. N. Thrasher ◽  
J. F. Nistal-Herrera ◽  
L. C. Keil ◽  
D. J. Ramsay

The roles of oropharyngeal and gastric factors in satiation and arginine vasopressin (AVP) secretion were examined in water-deprived dogs. Dogs were prepared with chronic gastric fistulas and received six treatments after 24 h of water deprivation: rehydration with H2O or extracellular fluid (ECF) with the fistula closed; rehydration with H2O or ECF with the fistula open; gastric administration of H2O or ECF via the fistula. Drinking occurred immediately after presentation and was always completed by 6 min. At the end of the 60-min period of observation, water was offered in order to assess the degree of satiety. No differences were observed between the volumes of H2O or ECF consumed. However, only absorption of the water drunk produced complete satiety assessed 60 min later. Drinking H2O caused a fall in plasma AVP 6 min before a detectable decline in osmolality and reached water-replete levels by 15 min after drinking. Drinking H2O or ECF plus removal via the fistula and drinking ECF also brought about a rapid decline in plasma AVP without any change in plasma osmolality. Gastric administration of H2O caused a fall in plasma AVP that coincided with the fall in osmolality, and gastric administration of ECF had no effect on plasma AVP. We conclude that oropharyngeal factors account for temporary satiety and the rapid inhibition of vasopressin secretion.


1982 ◽  
Vol 99 (4) ◽  
pp. 493-499 ◽  
Author(s):  
G. Valiquette ◽  
L. Martini

Abstract. The secretion of vasopressin has been shown recently to be influenced by gonadal steroids. To further evaluate the relevance of sex steroids in the control of vasopressin secretion, the vasopressin response to dehydration has been studied in normal, castrated and sex-steroid treated castrated male rats. Short-term (3 weeks) castration did not modify the vasopressin response to 48 h of water deprivation. Long-term (10 weeks) castration, on the other hand, consistently reduced the vasopressin response by more than 50%. In both cases, the osmolality was unaffected. Treatment of long-term castrated rats with testosterone, dihydrotestosterone, or oestradiol increased the vasopressin response to dehydration towards normal control levels. However, only oestradiol could restore it to and beyond normal levels, although all three steroids were given in doses that were equipotent in bringing back to normal the plasma LH levels of the castrated animals. Angiotensin-II generation may indirectly be augmented by oestradiol treatment and this may account for the effect of oestradiol here reported. No such mechanism, however, may be invoked in the case of androgens; a direct modulatory effect at the hypothalamic level is postulated for explaining their influence on vasopressin secretion.


2005 ◽  
Vol 289 (5) ◽  
pp. R1238-R1243 ◽  
Author(s):  
Edward M. Stricker ◽  
Myriam L. Hoffmann

The present study determined whether vasopressin (VP) secretion is inhibited by an oropharyngeal signal associated with swallowing fluids when dehydrated rats drink water, as it is when dehydrated dogs are used as experimental subjects (Thrasher, TN, Keil LC, and Ramsay DJ. Am J Physiol Regul Integr Comp Physiol 253: R509–R515, 1987). VP levels in systemic plasma (pVP) fell rapidly when rats drank water after overnight water deprivation. Systemic plasma Na+ concentration (pNa) also fell, but that change likely contributed little to the early inhibition of VP secretion. In contrast, consumption of water by dehydrated rats with an open gastric fistula had no effect on pVP, nor did consumption of isotonic saline by dehydrated rats; in neither case was pNa affected by fluid consumption. These findings provide no evidence that the act of drinking inhibits VP secretion in dehydrated rats. Thus some postgastric effect of the ingested water seems to be responsible for the inhibitory signal. These results are consistent with previous suggestions that an early inhibitory stimulus for VP secretion in rats is provided by postgastric visceral osmo- or Na+ receptors that sense the composition of the ingested fluid.


1990 ◽  
Vol 258 (4) ◽  
pp. F821-F830 ◽  
Author(s):  
S. Matsukawa ◽  
L. C. Keil ◽  
I. A. Reid

The observation that electrical stimulation of the renal nerves increases vasopressin secretion raises the possibility that the renal nerves may participate in the control of vasopressin secretion. In the present investigation, the effects of renal denervation on the vasopressin response to two reflex stimuli (nitroprusside infusion and hemorrhage) and two osmotic stimuli (hypertonic saline infusion and water deprivation) were studied in conscious, chronically prepared rabbits. Nitroprusside infusion in 13 intact and 14 denervated rabbits caused similar decreases in mean arterial pressure (MAP) and the increase in plasma arginine vasopressin concentration (PAVP) in intact (2.6 +/- 0.3 to 5.8 +/- 0.9 pg/ml, P less than 0.01) and denervated (2.8 +/- 0.3 to 5.7 +/- 1.3 pg/ml, P less than 0.01) rabbits was not significantly different. Hemorrhage (20 ml/kg) in 15 intact and 14 denervated rabbits caused similar decreases in MAP. Again, the increase in PAVP from 2.7 +/- 0.3 to 159.0 +/- 37.1 pg/ml (P less than 0.01) in intact and from 5.0 +/- 1.7 to 115.4 +/- 45.6 pg/ml (P less than 0.01) in denervated rabbits was not significantly different, nor was the relationship between PAVP and MAP in the two groups. In seven intact rabbits, hypertonic saline infusion increased PAVP from 4.0 +/- 0.9 to 10.9 +/- 2.8 pg/ml (P less than 0.05). The change in six denervated rabbits was not significantly different, nor was the relationship between PAVP and plasma osmolality. During water deprivation (24 h) in six intact rabbits, PAVP increased from 4.0 +/- 0.7 to 6.9 +/- 0.6 pg/ml (P less than 0.05). Again, the increase in PAVP in six denervated rabbits was not significantly different from that in the intact rabbits. The change in MAP during water deprivation in the two groups was also not significantly different. Renal cortical norepinephrine concentration in denervated kidneys was less than 10 ng/g wet wt. These results indicate that, in conscious rabbits, renal denervation does not impair the osmotic or reflex regulation of vasopressin secretion, nor does it interfere with blood pressure regulation during hypovolemia or hypotension.


1985 ◽  
Vol 68 (6) ◽  
pp. 669-674 ◽  
Author(s):  
P. A. Phillips ◽  
B. J. Rolls ◽  
J. G. G. Ledingham ◽  
J. J. Morton ◽  
M. L. Forsling

1. The thirst and plasma vasopressin responses to single-blind controlled intravenous angiotensin II infusions (2-16 ng min−1 kg−1) were investigated in ten healthy young men. 2. Thirst and vasopressin secretion were stimulated in four out of ten subjects. These effects occurred at plasma angiotensin concentrations well above those measured under physiological conditions associated with thirst and vasopressin secretion such as water deprivation. 3. Further studies are needed to define why only certain individuals respond to intravenous angiotensin II infusions and to determine whether potentiation of angiotensin-induced thirst and vasopressin secretion by other stimuli (e.g. hypovolaemia and hypertonicity) might occur in man, in particular under pathological conditions when plasma angiotensin levels are above the physiological range.


1991 ◽  
Vol 261 (5) ◽  
pp. R1226-R1233 ◽  
Author(s):  
B. H. Appelgren ◽  
T. N. Thrasher ◽  
L. C. Keil ◽  
D. J. Ramsay

Ingestion of water stimulates a powerful inhibitory input to secretion of arginine vasopressin (AVP) in many species. A previous study in dogs has suggested that the stimulus arises from activation of oropharyngeal receptors, but the nature of the stimulus is unknown. The objectives of this study were to determine if the taste, osmolality, or temperature of the solution ingested constituted an important element in the inhibitory mechanism and if these same attributes affected the volume ingested in response to 24 h of water deprivation in conscious dogs. Experiments consisted of a control period, a 6-min period of access to fluid, and a 60-min period after drinking, with blood samples taken frequently to assess changes in plasma AVP. Dogs were placed in a sling that allowed them to stand or lie supported with easy access to a bowl. The solutions were water at 20 and 38 degrees C; 0.9% NaCl at 20 and 38 degrees C; 1.8 and 2.7% NaCl at 20 degrees C; 5% glucose and mannitol and 10% mannitol at 20 degrees C; and liquified food at 20 degrees C. In the time-control experiment dogs were allowed to see but not drink water for 6 min.(ABSTRACT TRUNCATED AT 250 WORDS)


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