Prolonged stimulation of intrarenal V1 vasopressin receptors results in sustained hypertension

1994 ◽  
Vol 267 (5) ◽  
pp. R1217-R1225 ◽  
Author(s):  
E. Szczepanska-Sadowska ◽  
K. Stepniakowski ◽  
M. M. Skelton ◽  
A. W. Cowley
Keyword(s):  
Arterial Pressure ◽  
Intravenous Administration ◽  
Plasma Osmolality ◽  
Sprague Dawley ◽  
Sustained Hypertension ◽  
Body Sodium ◽  
Chronic Infusion ◽  
Vasopressin Receptors ◽  
Stimulation Of ◽  
Interstitial Infusion

In an earlier study, we reported that chronic intravenous administration of the V1 agonist [Phe2,Ile3,Orn8]vasopressin (V1AG) results in sustained hypertension. The present study was designed to determine whether V1-induced hypertension may be related specifically to intrarenal actions of this peptide. Chronic infusion of the V1 agonist into the medullary interstitial space of a single remaining kidney of normal, conscious Sprague-Dawley rats at the rate of 2 ng.kg-1.min-1 for 14 days resulted in a sustained rise of 18 mmHg of mean arterial pressure (MAP). After withdrawal of V1AG, MAP returned to the baseline level. During the first day of V1AG infusion, there was a net loss of body sodium and no evidence of fluid retention throughout the period of hypertension. Plasma osmolality, sodium and potassium concentration, and water intake and body weight were not significantly affected by medullary interstitial infusion of V1AG. Renal medullary interstitial infusion of an equimolar amount of arginine vasopressin (AVP) did not affect MAP. Chronic medullary interstitial infusion of the selective V1 antagonist d(CH2)5[Tyr(Me)2,Ala-NH(2)9]AVP in equimolar amounts (2.5 ng.kg-1.min-1) prevented the MAP increase elicited by intravenous V1AG. However, intravenous administration of the V1 antagonist at the same rate together with V1AG (n = 7) failed to prevent hypertension. The results indicate that hypertension can be elicited by chronic stimulation of renal medullary V1 vasopressin receptors. They also suggest that some V2 agonistic properties of AVP may restrict the hypertensive action of this hormone. The mechanism for the rise of arterial pressure remains to be determined.

Chronic intravenous administration of V1 arginine vasopressin agonist results in sustained hypertension

1994 ◽  
Vol 267 (2) ◽  
pp. H751-H756 ◽  
Author(s):  
A. W. Cowley ◽  
E. Szczepanska-Sadowska ◽  
K. Stepniakowski ◽  
D. Mattson
Keyword(s):  
Body Weight ◽  
Arginine Vasopressin ◽  
Plasma Catecholamines ◽  
Plasma Osmolality ◽  
Sprague Dawley ◽  
Prolonged Administration ◽  
Chronic Stimulation ◽  
Sustained Hypertension ◽  
Sprague Dawley Rats

Despite the well-recognized vasoconstrictor and fluid-retaining actions of vasopressin, prolonged administration of arginine vasopressin (AVP) to normal animals or humans fails to produce sustained hypertension. The present study was performed to elucidate the role of the V1 receptor in determining the ability of AVP to produce sustained hypertension. Conscious Sprague-Dawley rats with implanted catheters were infused with the selective V1 agonist, [Phe2,Ile3,Orn8]vasopressin (2 ng.kg-1.min-1), for 14 days in amounts that were acutely nonpressor. Blood pressure (MAP), heart rate (HR), body weight, and water intake (WI) were determined daily. Plasma AVP, plasma catecholamines norepinephrine and epinephrine, plasma osmolality, and electrolyte concentration were determined before and on days 1 and 7 of infusion. MAP increased significantly by 10.4 +/- 4.5 mmHg on day 1 and rose to 22 +/- 5 mmHg above control by day 14 (transient decrease on days 6-9) and then fell to control levels after the infusion was stopped. HR did not change significantly. Plasma AVP immunoreactivity increased from 2.5 +/- 0.3 to 10.9 +/- 2.1 pg/ml, whereas norepinephrine tended to fall only on day 1, with epinephrine only slightly elevated on day 7. No evidence of fluid retention was found, and rats lost sodium only on the first day of V1 agonist infusion. Body weight increased throughout the study but was unrelated to the changes of MAP. We conclude that chronic stimulation of V1 receptors results in sustained hypertension in rats.

Effect of baroreceptor denervation on stimulation of drinking by angiotensin II in conscious dogs

1991 ◽  
Vol 260 (3) ◽  
pp. E333-E337 ◽  
Author(s):  
C. K. Klingbeil ◽  
V. L. Brooks ◽  
E. W. Quillen ◽  
I. A. Reid
Keyword(s):  
Blood Pressure ◽  
Drinking Water ◽  
Angiotensin Ii ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Carotid Sinus ◽  
Plasma Osmolality ◽  
Plasma Angiotensin ◽  
High Doses ◽  
Stimulation Of

Angiotensin II causes marked stimulation of drinking when it is injected centrally but is a relatively weak dipsogen when administered intravenously. However, it has been proposed that the dipsogenic action of systemically administered angiotensin II may be counteracted by the pressor action of the peptide. To test this hypothesis, the dipsogenic action of angiotensin II was investigated in dogs, in which low and high baroreceptor influences had been eliminated by denervation of the carotid sinus, aortic arch, and heart. In five sham-operated dogs, infusion of angiotensin II at 10 and 20 ng.kg-1.min-1 increased plasma angiotensin II concentration to 109.2 +/- 6.9 and 219.2 +/- 38.5 pg/ml and mean arterial pressure by 20 and 29 mmHg, respectively, but did not induce drinking. In four baroreceptor-denervated dogs, the angiotensin II infusions produced similar increases in plasma angiotensin II concentration and mean arterial pressure but, in contrast to the results in the sham-operated dogs, produced a dose-related stimulation of drinking. Water intake with the low and high doses of angiotensin II was 111 +/- 44 and 255 +/- 36 ml, respectively. The drinking responses to an increase in plasma osmolality produced by infusion of hypertonic sodium chloride were not different in the sham-operated and baroreceptor-denervated dogs. These results demonstrate that baroreceptor denervation increases the dipsogenic potency of intravenous angiotensin II and provides further support for the hypothesis that the dipsogenic action of intravenous angiotensin II is counteracted by the rise in blood pressure.

Mechanism of prostaglandin E2-induced increase of proximal sodium reabsorption in the rat

1990 ◽  
Vol 258 (1) ◽  
pp. R82-R86 ◽  
Author(s):  
Y. Kinoshita ◽  
F. G. Knox
Keyword(s):  
Angiotensin Ii ◽  
Prostaglandin E2 ◽  
Rat Kidney ◽  
Sodium Reabsorption ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Convoluted Tubules ◽  
Stimulation Of ◽  
Interstitial Infusion

Prostaglandin E2, when infused directly into the renal interstitium, enhances sodium reabsorption by the superficial proximal convoluted tubules of anesthetized Sprague-Dawley rats. The present study was designed to investigate the role of angiotensin II in the prostaglandin E2-induced stimulation of proximal sodium reabsorption. Micropuncture at the superficial late proximal tubule demonstrated a significant increase in the fractional reabsorption of sodium from 39.9 +/- 2.3% in control conditions to 51.8 +/- 3.0% (n = 9, P less than 0.01) during the renal interstitial infusion of prostaglandin E2. The stimulatory effect of prostaglandin E2 on proximal sodium reabsorption was markedly attenuated by pretreatment with saralasin. During intravenous saralasin infusion, prostaglandin E2 did not significantly change the fractional reabsorption of sodium from 42.2 +/- 5.8 to 45.4 +/- 6.0% (n = 7, NS). In summary, the stimulatory effect of renal interstitial infusion of prostaglandin E2 on proximal sodium reabsorption was attenuated by pretreatment with saralasin. Therefore renal interstitial infusion of prostaglandin E2 may enhance proximal sodium reabsorption, at least in part, through stimulation of angiotensin II production in the rat kidney.

Renal tubular vasopressin receptors downregulated by dehydration

1988 ◽  
Vol 254 (3) ◽  
pp. C404-C410 ◽  
Author(s):  
M. Steiner ◽  
M. I. Phillips
Keyword(s):  
Binding Sites ◽  
Plasma Osmolality ◽  
Fold Increase ◽  
Scatchard Analysis ◽  
Sprague Dawley ◽  
Single Class ◽  
Physiological Regulation ◽  
Lysine Vasopressin ◽  
Vasopressin Receptors ◽  
Renal Tubular

Receptors for arginine vasopressin (AVP) were characterized in tubular epithelial basolateral membranes (BL membranes) prepared from the kidneys of male Sprague-Dawley rats. Association of [3H]AVP was rapid, reversible, and specific. Saturation studies revealed a single class of saturable binding sites with a maximal binding (Bmax) of 184 +/- 15 fmol/mg protein and a KD of 0.61 +/- 0.04 nM. IC50S for AVP, lysine vasopressin, and oxytocin were 0.74 nM, 9.7 nM, and greater than 1 microM, respectively. The V2 receptor antagonist was more than 3,700 times as effective in displacing [3H]AVP than was the V1 antagonist. To investigate the physiological regulation of vasopressin receptors, the effects of elevated levels of circulating AVP on receptor characteristics were studied. Seventy-two-hour water deprivation significantly elevated plasma osmolality and caused an 11.5-fold increase in plasma [AVP]. Scatchard analysis revealed a 38% decrease in the number of AVP receptors on the BL membranes from dehydrated animals. The high-affinity binding sites on the BL membranes fit the pharmacological profile for adenylate cyclase-linked vasopressin receptors (V2), which mediate the antidiuretic action of the hormone. We conclude that physiologically elevated levels of AVP can downregulate vasopressin receptors in the kidney.

Abstract 434: Increased Dietary Salt Intake Enhances the Exercise Pressor Reflex

Hypertension ◽  
2013 ◽  
Vol 62 (suppl_1) ◽  
Author(s):  
Katsuya Yamauchi ◽  
Hirotsugu Tsuchimochi ◽  
Sean D Stocker ◽  
Marc P Kaufman
Keyword(s):  
Electrical Stimulation ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Salt Intake ◽  
Sprague Dawley ◽  
Dietary Salt ◽  
Exercise Pressor Reflex ◽  
Pressor Reflex ◽  
Sympathetic Responses ◽  
Stimulation Of

Increased dietary salt in rats has been shown to sensitize central sympathetic circuits and enhance sympathetic responses to several stressors, including hyperinsulinemia, intracerebroventricular injection of angiotensin and electrical stimulation of sciatic nerve afferents. These findings prompted us to test the hypothesis that increased dietary salt enhanced the exercise pressor reflex.Male Sprague-Dawley rats were fed 0.1% (n=16) or 4.0% (n=18) NaCl chow for 14-21 days. Then, rats were decerebrated and the exercise pressor reflex was produced by static contraction of the hindlimb muscles through electrical stimulation of the cut peripheral ends of the L4 and L5 ventral roots. We found that contraction produced a significantly greater increase in mean arterial pressure of rats fed 4.0% NaCl (24±2 mmHg) versus 0.1% NaCl (15±2 mmHg). Baseline mean arterial pressure was not different between 0.1% versus 4.0% NaCl diets (79±5 vs 83±4 mmHg). The tension time indices were not different between the 0.1% (17±1 kg per s) versus 4.0% (18.2±2 kg s) NaCl groups (P = 0.422). The enhanced responsiveness to contraction appeared to be attributable to sensitized group III mechanoreceptors because the renal and lumbar sympathetic responses to contraction were augmented within 200 ms of the onset of contraction. Section of the L4 and L5 dorsal roots abolished the pressor responses to contraction in both groups of rats, an effect showing that the responses were reflex in origin. We conclude that increased dietary salt can enhance the reflex sympathetic responses to static exercise.

Water retention after oral chlorpropamide is associated with an increase in renal papillary arginine vasopressin receptors

1995 ◽  
Vol 132 (4) ◽  
pp. 459-464 ◽  
Author(s):  
J Hensen ◽  
M Haenelt ◽  
P Gross
Keyword(s):  
Arginine Vasopressin ◽  
Water Retention ◽  
Specific Activity ◽  
High Specific Activity ◽  
Plasma Osmolality ◽  
Dependent Diabetes Mellitus ◽  
Scatchard Analysis ◽  
Sprague Dawley ◽  
Water Excretion ◽  
Vasopressin Receptors

Hensen J, Haenelt M, Gross P. Water retention after oral chlorpropamide is associated with an increase in renal papillary arginine vasopressin receptors. Eur J Endocrinol 1995;132:459–64. ISSN 0804–4643 Chlorpropamide (CP), a sulfonylurea used for treatment of non-insulin dependent diabetes mellitus, is known to potentiate the antidiuretic action of arginine vasopressin (AVP), predisposing to hyponatremia. It has been suggested that CP acts directly on the antidiuretic vasopressin receptor. Detailed studies on the influence of CP on the AVP receptor, however, have been hampered by lack of a suitable radioligand. Using a newly developed radioiodinated derivative of AVP with high specific activity and high affinity for the AVP V2-receptor (125I-[8-(p-(OH)-phenylpropionyl)]-LVP), we studied the role of AVP V2-receptors in CP-induced water retention. Male-Sprague-Dawley rats were treated orally with 40 mg CP/day or placebo for 7 days, after which Scatchard analysis was performed using membranes prepared from homogenized renal papilla. After oral water load, CP-treated rats but not control rats showed a significant decrease in plasma osmolality (289 ±2.2 to 284±0.8 mosmol/kg, p < 0.05). The Kd was 0.69 ± 0.16 nmol/l in controls and 0.70 ± 0.12 nmol/l after CP treatment (NS); Bmax was 129 ± 5.3 nmol/kg protein in controls (N = 8). Chlorpropamide significantly increased receptor density (Bmax) to 167±8.4 nmol/kg protein (N = 8) (p<0.05). Plasma AVP did not change significantly during CP treatment. These data show for the first time that CP in vivo increases the density of AVP V2 receptors without altering plasma AVP. This is associated with an impairment in water excretion. Our experiments and recent reports on CP-induced inhibition of AVP binding suggest that the AVP augmentation effect of CP is related to interference of CP with the AVP V2-receptor. Johannes Hensen, Department of Medicine I, Division of Endocrinology and Metabolism, Krankenhausstr. 12, 91054 Erlangen, Germany

Electrical stimulation of the carotid sinus lowers arterial pressure and improves heart rate variability in l-NAME hypertensive conscious rats

2020 ◽  
Vol 43 (10) ◽  
pp. 1057-1067 ◽  
Author(s):  
Gean Domingos-Souza ◽  
Fernanda Machado Santos-Almeida ◽  
César Arruda Meschiari ◽  
Nathanne S. Ferreira ◽  
Camila A. Pereira ◽  
...  
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Electrical Stimulation ◽  
Arterial Pressure ◽  
Carotid Sinus ◽  
Conscious Rats ◽  
Stimulation Of

EFFECT OF EXPERIMENTALLY INDUCED THYROIDITIS ON BIOSYNTHESIS OF THYROXINE IN RATS

1969 ◽  
Vol 62 (1) ◽  
pp. 11-20 ◽  
Author(s):  
Colum A. Gorman ◽  
James W. Anderson ◽  
Eunice V. Flock ◽  
Charles A. Owen ◽  
Khalil G. Wakim
Keyword(s):  
Intravenous Administration ◽  
Hashimoto's Thyroiditis ◽  
Sprague Dawley ◽  
Thyroid Extract ◽  
Histologic Appearance ◽  
Gland Weight ◽  
Sprague Dawley Rats ◽  
Thyroid Glands ◽  
And Control ◽  
Experimentally Induced

ABSTRACT Thyroiditis was induced in Sprague-Dawley rats by repeated immunization with thyroid extract and Freund's adjuvant. Immunized and control animals were killed at intervals up to 6 hours after intravenous administration of 131I as iodide at 5, 8 and 10 weeks after the first injection. Radioiodinated compounds in the thyroid glands were identified chromatographically. Evidence of moderate thyroiditis was present (histologic appearance, gland weight, and protein-bound iodine-butanol-extractable iodine difference) but the rate of incorporation of radioiodide into thyroxine, the percentage of radioactivity in the gland as iodide, and the MIT/DIT ratio were not significantly different in immunized and control animals. The MIT/DIT ratio was found to vary with time after 131I administration in both immunized and control animals. These studies did not uncover a defect in organification of iodide in experimental thyroiditis similar to that described by others in humans with Hashimoto's thyroiditis.

scholarly journals Further evidence against the role renal medullary perfusion in short-term control of arterial pressure in normotensive and mildly or overtly hypertensive rats

2021 ◽  
Vol 473 (4) ◽  
pp. 623-631
Author(s):  
Bożena Bądzyńska ◽  
Iwona Baranowska ◽  
Janusz Sadowski
Keyword(s):  
Arterial Pressure ◽  
Renal Excretion ◽  
Sodium Concentration ◽  
Sprague Dawley ◽  
Hypertensive Rats ◽  
Critical Determinant ◽  
Human Hypertension ◽  
Pressure Elevation ◽  
Doppler Probe ◽  
Medullary Tissue

AbstractEarlier evidence from studies of rat hypertension models undermines the widespread view that the rate of renal medullary blood flow (MBF) is critical in control of arterial pressure (MAP). Here, we examined the role of MBF in rats that were normotensive, with modest short-lasting pressure elevation, or with overt established hypertension. The groups studied were anaesthetised Sprague-Dawley rats: (1) normotensive, (2) with acute i.v. norepinephrine-induced MAP elevation, and (3) with hypertension induced by unilateral nephrectomy followed by administration of deoxycorticosterone-acetate (DOCA) and 1% NaCl drinking fluid for 3 weeks. MBF was measured (laser-Doppler probe) and selectively increased using 4-h renal medullary infusion of bradykinin. MAP, renal excretion parameters and post-experiment medullary tissue osmolality and sodium concentration were determined. In the three experimental groups, baseline MAP was 117, 151 and 171 mmHg, respectively. Intramedullary bradykinin increased MBF by 45%, 65% and 70%, respectively, but this was not associated with a change in MAP. In normotensive rats a significant decrease in medullary tissue sodium was seen. The intramedullary bradykinin specifically increased renal excretion of water, sodium and total solutes in norepinephrine-treated rats but not in the two other groups. As previously shown in models of rat hypertension, in the normotensive rats and those with acute mild pressure elevation (resembling labile borderline human hypertension), 4-h renal medullary hyperperfusion failed to decrease MAP. Nor did it decrease in DOCA-salt model mimicking low-renin human hypertension. Evidently, within the 4-h observation, medullary perfusion was not a critical determinant of MAP in normotensive and hypertensive rats.

High-fat diet is associated with blunted splanchnic sympathoinhibitory responses to gastric leptin and cholecystokinin: implications for circulatory control

2011 ◽  
Vol 300 (3) ◽  
pp. H961-H967 ◽  
Author(s):  
Jackie M. Y. How ◽  
Barbara C. Fam ◽  
Anthony J. M. Verberne ◽  
Daniela M. Sartor
Keyword(s):  
Arterial Pressure ◽  
High Fat Diet ◽  
Cardiovascular Effects ◽  
Vagal Afferents ◽  
Sprague Dawley ◽  
High Fat ◽  
Lower Plasma ◽  
Lower Tertile ◽  
Circulatory Control ◽  
Plasma Leptin

Gastric leptin and cholecystokinin (CCK) act on vagal afferents to induce cardiovascular effects and reflex inhibition of splanchnic sympathetic nerve discharge (SSND) and may act cooperatively in these responses. We sought to determine whether these effects are altered in animals that developed obesity in response to a medium high-fat diet (MHFD). Male Sprague-Dawley rats were placed on a low-fat diet (LFD; n = 8) or a MHFD ( n = 24) for 13 wk, after which the animals were anesthetized and artificially ventilated. Arterial pressure was monitored and blood was collected for the determination of plasma leptin and CCK. SSND responses to leptin (15 μg/kg) and CCK (2 μg/kg) administered close to the coeliac artery were evaluated. Collectively, MHFD animals had significantly higher plasma leptin but lower plasma CCK levels than LFD rats ( P < 0.05), and this corresponded to attenuated or reversed SSND responses to CCK (LFD, −21 ± 2%; and MHFD, −12 ± 2%; P < 0.05) and leptin (LFD, −6 ± 2%; and MHFD, 4 ± 1%; P < 0.001). Alternatively, animals on the MHFD were stratified into obesity-prone (OP; n = 8) or obesity-resistant (OR; n = 8) groups according to their weight gain falling within the upper or lower tertile, respectively. OP rats had significantly higher resting arterial pressure, adiposity, and plasma leptin but lower plasma CCK compared with LFD rats ( P < 0.05). The SSND responses to CCK or leptin were not significantly different between OP and OR animals. These results demonstrate that a high-fat diet is associated with blunted splanchnic sympathoinhibitory responses to gastric leptin and CCK and may impact on sympathetic vasomotor mechanisms involved in circulatory control.

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