A comparison of the vasopressin response of rats to intraperitoneal and intravenous administration of hypertonic saline, and the effect of opioid and aminergic antagonists

1988 ◽  
Vol 116 (2) ◽  
pp. 217-224 ◽  
Author(s):  
M. L. Forsling ◽  
C. Matziari ◽  
L. Aziz

ABSTRACT The vasopressin response of rats to i.p. injection of hypertonic sodium chloride (1·5 mol/l) was compared with that following i.v. infusion of 1·05 mol sodium chloride/l. The two regimes produced a similar vasopressin response in terms of the osmotic threshold, although the slopes of the plot of plasma vasopressin levels against plasma osmolality were not identical. Pretreatment with naloxone and levallorphan increased the resting vasopressin levels and effectively potentiated vasopressin release in response to hypertonic saline by reducing the osmotic threshold for hormone release. Thus, opioid peptides appear to exert an inhibitory effect on vasopressin release under resting and stimulated conditions. The adrenoreceptor antagonists propanolol, phenyoxybenzamine and phentolamine produced a fall in resting vasopressin concentrations while propanolol and phenoxybenzamine potentiated the osmotic release of vasopressin in association with a fall in the osmotic threshold. This would suggest that noradrenergic pathways are excitatory at rest while having an inhibitory effect on the osmotic response. Metoclopramide also produced a fall in resting plasma vasopressin concentrations while increasing the osmotic response. In contrast haloperidol did not affect the vasopressin response. J. Endocr. (1988) 116, 217–224

1987 ◽  
Vol 252 (6) ◽  
pp. R1138-R1142 ◽  
Author(s):  
C. J. Thompson ◽  
J. M. Burd ◽  
P. H. Baylis

Drinking rapidly abolishes thirst and vasopressin secretion in dehydrated humans before major changes in plasma osmolality are observed. We studied the effects of drinking on plasma vasopressin and thirst in seven healthy volunteers rendered hypernatremic by the infusion of hypertonic (855 mmol/l) sodium chloride solution. Thirst was measured on a visual analogue scale (0-10 cm). Infusion of hypertonic saline caused linear increases in plasma osmolality (289 +/- 1 to 306 +/- 1 mosmol/kg, mean +/- SE, P less than 0.001), plasma vasopressin (0.6 +/- 0.2 to 6.4 +/- 1.9 pmol/l, P less than 0.001), and thirst (1.4 +/- 0.4 to 7.4 +/- 0.5 cm, P less than 0.001). Water was allowed 15 min after cessation of the infusion, and within 5 min of drinking both plasma vasopressin and thirst were significantly lower than postinfusion. After 20 min of drinking, plasma vasopressin had fallen from 6.5 +/- 0.9 to 1.3 +/- 0.3 pmol/l (P less than 0.001) and thirst from 7.7 +/- 0.5 to 1.0 +/- 0.2 cm (P less than 0.001) despite no significant change in plasma osmolality (306 +/- 0.9 to 304 +/- 0.8 mosmol/kg, P = 0.17), and the drinking of 1,200 +/- 60 ml of water, over 85% of the mean cumulative water intake in the 30-min drinking period. Control studies in the same subjects showed comparable rises in plasma vasopressin, plasma osmolality, and thirst during hypertonic saline infusion but no fall in any of these parameters during an equivalent 30-min period after the infusions, during which water was withheld.(ABSTRACT TRUNCATED AT 250 WORDS)


1988 ◽  
Vol 74 (6) ◽  
pp. 599-606 ◽  
Author(s):  
C. J. Thompson ◽  
S. N. Davis ◽  
P. C. Butler ◽  
J. A. Charlton ◽  
P. H. Baylis

1. Osmotically stimulated thirst and vasopressin release were studied during infusions of hypertonic sodium chloride and hypertonic d-glucose in euglycaemic clamped diabetic patients and healthy controls. 2. Infusion of hypertonic sodium chloride caused similar elevations of plasma osmolality in diabetic patients (288.0 ± 1.0 to 304.1 ± 1.6 mosmol/kg, mean ± sem, P < 0.001) and controls (288.6 ± 0.9 to 305.7 ± 0.6 mosmol/kg, P < 0.001), accompanied by progressive increases in plasma vasopressin (diabetic patients, 0.9 ± 0.3 to 7.7 ± 1.5 pmol/l, P < 0.001; controls 0.5 ± 0.1 to 6.5 ± 1.0 pmol/l, P < 0.001) and thirst ratings (diabetic patients 1.0 ± 0.2 to 7.1 ± 0.5 cm, P < 0.001; controls 1.8 ± 0.4 to 8.0 ± 0.5 cm, P < 0.001) in both groups. 3. Drinking rapidly abolished thirst and vasopressin secretion before major changes in plasma osmolality occurred in both diabetic patients and healthy controls. 4. There were close and significant correlations between plasma vasopressin and plasma osmolality (diabetic patients, r = + 0.89, controls r = + 0.93) and between thirst and plasma osmolality (diabetic patients r = +0.95, controls r = +0.97) in both diabetic patients and healthy controls during hypertonic saline infusion. 5. Hypertonic d-glucose infusion caused similar elevations in blood glucose in diabetic patients (4.0 ± 0.2 to 20.1 ± 1.2 mmol/l, P < 0.001) and healthy controls (4.3 ± 0.1 to 19.3 ± 1.2 mmol/l, P < 0.001) but did not change plasma vasopressin or thirst ratings. There was no correlation between plasma osmolality and either thirst or plasma vasopressin during hypertonic d-glucose infusion. 6. The characteristics of osmoregulated thirst and vasopressin release are similar in health and diabetes mellitus. As hyperglycaemia was not dipsogenic, however, the thirst of poorly controlled diabetes mellitus may be due to hypovolaemia secondary to polyuria rather than hyperosmolality due to elevated blood glucose concentrations.


1993 ◽  
Vol 71 (3-4) ◽  
pp. 222-226 ◽  
Author(s):  
Ruth A. Cridland ◽  
Norman W. Kasting

The osmosensitivity of peripheral vasopressin release was studied during healthy thermoregulation and endotoxin-induced fever. There was an increase in osmosensitivity following bolus injection of saline in febrile rats. These animals displayed a steeper slope in the linear relationship between plasma osmolality and plasma vasopressin levels compared with afebrile animals. The change in regression slope was due to a significantly lower plasma osmolality in febrile rats. The plasma osmolality of animals infused with hypertonic saline was similarly decreased, but data analysis failed to show a significant change in the regression slope. Osmotic thresholds were not altered in either group. There was an increased urine output in febrile rats, and consequently these animals excreted greater amounts of salts than afebrile rats. This could account for the lower plasma osmolality observed in the febrile rat.Key words: endotoxin, fever, osmolality, vasopressin.


1980 ◽  
Vol 73 (4) ◽  
pp. 255-260 ◽  
Author(s):  
P H Baylis ◽  
G L Robertson

Hypertonic saline was infused into 11 volunteers to osmotically stimulate vasopressin secretion. A strong positive correlation between plasma arginine vasopressin (PAVP) and plasma osmolality (Pos) was obtained, defined by the function PAVP = 0.63 (Pos – 284), r = +0.80, P < 0.001. The sensitivity of vasopressin secretion to osmotic stimulation was represented by the slope of the expression and the theoretical threshold of vasopressin release by the abscissal intercept. Plasma osmolality at the onset of thirst was 298.5 ± 1.1 mmol/kg. Application of hypertonic saline infusion to 10 polyuric patients clearly separated those with normal osmoregulation of vasopressin secretion from those with cranial diabetes insipidus.


1988 ◽  
Vol 254 (4) ◽  
pp. R641-R647 ◽  
Author(s):  
T. J. Vokes ◽  
N. M. Weiss ◽  
J. Schreiber ◽  
M. B. Gaskill ◽  
G. L. Robertson

Changes in osmoregulation during normal menstrual cycle were examined in 15 healthy women. In 10 women, studied repetitively during two consecutive menstrual cycles, basal plasma osmolality, sodium, and urea decreased by 4 mosmol/kg, 2 meq/l, and 0.5 mM, respectively (all P less than 0.02) from the follicular to luteal phase. Plasma vasopressin, protein, hematocrit, mean arterial pressure, and body weight did not change. In five other women, diluting capacity and osmotic control of thirst and vasopressin release were assessed in follicular, ovulatory, and luteal phases. Responses of thirst and/or plasma vasopressin, urine osmolality, osmolal and free water clearance to water loading, and infusion of hypertonic saline were normal and similar in the three phases. However, the plasma osmolality at which plasma vasopressin and urine osmolality were maximally suppressed as well as calculated osmotic thresholds for thirst and vasopressin release were lower by 5 mosmol/kg in the luteal than in the follicular phase. This lowering of osmotic thresholds for thirst and vasopressin release, which occurs in the luteal phase, is qualitatively similar to that observed in pregnancy and should be taken into account when studying water balance and regulation of vasopressin secretion in healthy cycling women.


1982 ◽  
Vol 243 (4) ◽  
pp. E287-E292 ◽  
Author(s):  
C. E. Wade ◽  
P. Bie ◽  
L. C. Keil ◽  
D. J. Ramsay

Seven dogs prepared with carotid loops were used to evaluate the responsiveness of the cerebral osmoreceptors regulating plasma vasopressin concentration (pAVP). Intracarotid and intravenous infusions of hypo- and hypertonic solutions were used to alter cerebral plasma osmolality. Bilateral intracarotid infusion of hypertonic saline (0.90 mmol NaCl kg-1 . min-1 . artery-1) significantly elevated jugular vein plasma osmolality (pOsm) in the first minute (P less than 0.05). Systemic values, determined from saphenous vein samples, were increased after 6 min. After 4 min of infusion, systemic pAVP was significantly increased, attaining a constant level at 6 min. Subsequent experiments with infusions 6 min in duration demonstrated that hypertonic saline infused intracarotidly significantly increased pAVP in a dose-related fashion, whereas similar solutions administered intravenously did not alter pAVP. Hypotonic infusions (intravenous or intracarotid) did not change pAVP consistently. The lack of a depression in pAVP during hypotonic infusions is consistent with the argument that jugular pOsm must be elevated above a threshold to stimulate the release of vasopressin. Linear relationships were demonstrated for jugular pNa+ and pOsm to pAVP employing the threshold model. Cerebral osmoreceptors that regulate plasma vasopressin concentration respond linearly to increasing tonicity above a threshold stimulating the release of vasopressin.


1994 ◽  
Vol 267 (4) ◽  
pp. R923-R928 ◽  
Author(s):  
M. Ota ◽  
J. T. Crofton ◽  
H. Liu ◽  
G. Festavan ◽  
L. Share

It has been demonstrated that the neurohypophysial hormones can be released intrahypothalamically by the paraventricular (PVN) and supraoptic nuclei. The present experiments were undertaken to determine whether a physiological stimulus for vasopressin release, increased plasma osmolality, will stimulate the release of vasopressin by the PVN into the surrounding interstitial fluid, and whether the responses are affected by gender. Intravenous infusion of 2.5 M NaCl for 60 min (0.1 ml.kg-1.min-1) in conscious rats resulted in an increased vasopressin concentration in the dialysate from a microdialysis probe adjacent to the PVN. This response was greater in nonestrous females than in males. On the other hand, the rise in the plasma vasopressin concentration was greater in males than in nonestrous females. Mean arterial blood pressure increased and heart rate decreased, but these responses were not affected by gender. The role of centrally released vasopressin in the control of the peripheral release of vasopressin is conjectural, but both responses may be modulated by the gonadal steroid hormones.


1994 ◽  
Vol 267 (4) ◽  
pp. R1089-R1097 ◽  
Author(s):  
R. Keil ◽  
R. Gerstberger ◽  
E. Simon

Under thermoneutral conditions conscious rabbits received systemic infusions of NaCl as hypertonic solution (90 mueq.min-1.kg body wt-1), which raised their plasma osmolality from 283 to 312 mosmol/kgH2O. Rabbits receiving isotonic saline served as controls. Hypertonic stimulation induced a 60% reduction of both respiratory frequency and evaporative water loss. Rectal temperature rose by 0.4 degrees C despite enhanced peripheral vasodilation as indicated by increased ear skin temperature. Plasma vasopressin (AVP), aldosterone (ALDO), and corticosterone (COR) were significantly elevated from 6 to 16 pg/ml, 90 to 180 pg/ml, and 17 to 40 ng/ml, respectively. To elucidate the importance of central temperature for AVP and adrenal corticosteroid release, hypothalamic thermal stimulations (20 min) were superimposed during established iso- and hyperosmotic steady-state conditions. Different from isosmotic controls, hyperosmotic animals responded to hypothalamic cooling (37 degrees C) with a significant decrease in plasma AVP from 16 to 13 pg/ml and to hypothalamic warming (41 degrees C) with a significant rise from 16 to 19 pg/ml. A weak temperature effect on COR release was also disclosed, especially of hypothalamic cooling, which significantly lowered plasma COR from 42 to 34 ng/ml. These results provide evidence for positive local temperature coefficients of hypothalamic control of AVP release and suggest a similar property also for the control of COR release by the hypothalamo-adenohypophysial axis.


1990 ◽  
Vol 124 (2) ◽  
pp. 277-284 ◽  
Author(s):  
K. Peysner ◽  
M. L. Forsling

ABSTRACT Plasma vasopressin concentrations have previously been shown to vary during the oestrous cycle of the rat, being highest on the morning of pro-oestrus and lowest on dioestrus day 1. To determine the effect of gonadal steroids on vasopressin secretion and fluid balance, mature rats were ovariectomized and given oestrogen, progesterone or vehicle alone s.c. for periods of up to 16 days. Plasma vasopressin concentrations fell after ovariectomy and this was reflected in an increase in 24-h urine volume. The normal increase in plasma vasopressin concentrations seen over daylight hours was also suppressed. The change in vasopressin concentrations observed on steroid treatment depended upon both the dose and the duration. High doses of oestrogen were associated with a fall in plasma vasopressin, probably as a result of fluid retention. Thus, of an initial group of rats given silicone elastomer implants containing 50, 500 or 1000 μg oestradiol in oil, plasma vasopressin concentrations were reduced after 7 days treatment with 1000 μg oestradiol implants in association with reduced plasma sodium concentrations. Daily s.c. injections of 100 μg oestradiol benzoate/100 g body weight produced an immediate small increase in plasma vasopressin concentrations, but by 14 days the plasma concentrations of 0·7 ± 0·16 pmol/l (mean ± s.e.m.) had fallen significantly and were less than those in the vehicle-treated group (1·2± 0·26 pmol/l). However, after treatment for 14 days with implants containing only 50 μg oestradiol, plasma vasopressin concentations were higher compared with the group receiving vehicle alone, despite the fact that the plasma osmolality was lower in the latter group, suggesting a long term resetting of the osmoreceptors. Progesterone treatment with two implants containing 17·5 mg progesterone in oil was associated with an initial suppression of plasma vasopressin concentrations, but 16 days after the implant the plasma concentrations were higher than in the control group. Neither oestrogen nor progesterone restored the vasopressin concentrations to those seen in the intact animal. Oestrogen treatment resulted in a reduction in food and water intake, whereas progesterone treatment produced an initial increase in food and water intake, and a fall in plasma osmolality which could account for the reduced plasma vasopressin. This was followed by an increase in urine flow over days 6 to 15. Thus ovariectomy had a marked effect on circulating vasopressin concentrations, probably as a result of complex changes since administration of either oestrogen or progesterone in doses giving normal circulating concentrations had little effect. Journal of Endocrinology (1990) 124, 277–284


1992 ◽  
Vol 262 (6) ◽  
pp. R1154-R1157 ◽  
Author(s):  
R. F. Parrott ◽  
M. L. Forsling

Bolus intravenous injections of cholecystokinin (CCK) octapeptide induce a rapid rise in plasma vasopressin and a later increase in cortisol in the prepubertal pig. To determine whether these endocrine responses involve CCK-A or CCK-B receptors, this experiment investigated the effect of CCK (1 microgram/kg) in pigs (n = 7) pretreated with the CCK-A antagonist L 364718 (70 microgram/kg) or the CCK-B antagonist L 365260 (10 ng/kg and 10 micrograms/kg). The animals were prepared with jugular vein catheters and given the antagonist vehicle, L 364718, or L 365260 10 min before administration of CCK or saline. Analysis of hormone concentrations in blood samples taken 2, 5, 10, and 20 min after the second injection indicated that an abrupt rise in vasopressin, detectable within 2 min of CCK administration, occurred after vehicle or L 365260 pretreatment but not when CCK was preceded by L 364718. In contrast, the rise in plasma cortisol that was observed approximately 15 min after CCK injection was not prevented by either antagonist. Thus peripherally administered CCK induces vasopressin release by CCK-A receptor activation, in agreement with its inhibitory effect on food intake in this species. However, the effect of CCK on cortisol secretion does not appear to involve either CCK-A or CCK-B receptors.


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