Role of paraventricular nucleus parvicellular neurons in the compensatory responses to graded hemorrhage

1998 ◽  
Vol 275 (1) ◽  
pp. R278-R285 ◽  
Author(s):  
M. L. Blair ◽  
A. Want ◽  
J. A. Olschowka ◽  
D. Piekut
Keyword(s):  
Heart Rate ◽  
Blood Loss ◽  
Plasma Renin ◽  
Hypothalamic Nucleus ◽  
Sprague Dawley ◽  
Compensatory Responses ◽  
Basal Serum ◽  
Sprague Dawley Rats ◽  
Corticosterone Response

The goal of this study was to determine the role of the parvicellular component of the paraventricular hypothalamic nucleus (PVH) in the compensatory responses to blood loss. Male Sprague-Dawley rats were prepared with bilateral ibotenate lesions of the parvicellular PVH (PVHx; n = 5) or with sham lesions (Sham; n = 8). After >10 days recovery, hemorrhage was performed by gradual withdrawal of 16 ml/kg blood over 34 min via an indwelling femoral arterial catheter while the rats were conscious and unrestrained. Basal serum corticosterone levels, plasma renin concentration (PRC), mean arterial pressure, and heart rate did not differ between PVHx and Sham, whereas basal hematocrit was lower in PVHx than Sham (40 ± 1 vs. 44 ± 1; P < 0.05). After hemorrhage, corticosterone increased fourfold in Sham ( P < 0.001) but did not increase significantly in PVHx. However, the blood pressure, heart rate, PRC, and hemodilution responses to hemorrhage were the same in Sham and PVHx during both the normotensive (7–13 ml/kg blood loss) and hypotensive (16 ml/kg blood loss) phases. In conclusion, the parvicellular PVH is essential for the corticosterone response, but not for the cardiovascular or renin responses to blood loss.

Area postrema: essential for support of arterial pressure after hemorrhage in rats

1990 ◽  
Vol 258 (6) ◽  
pp. R1472-R1478 ◽  
Author(s):  
K. M. Skoog ◽  
M. L. Blair ◽  
C. D. Sladek ◽  
W. M. Williams ◽  
M. L. Mangiapane
Keyword(s):  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Data Acquisition ◽  
Area Postrema ◽  
Plasma Renin ◽  
Base Line ◽  
Sprague Dawley ◽  
Time Period ◽  
Sprague Dawley Rats

Previous studies have indicated that the area postrema (AP) of the rat is necessary for the development of chronic angiotensin-dependent hypertension. The present study assesses the role of the AP in the maintenance of arterial pressure during hemorrhage. Sprague-Dawley rats were given sham or AP lesions 1 wk before the experiment. They were instrumented with femoral arterial and venous catheters 2 days before the experiment. On the day of the experiment, base-line mean arterial pressure (MAP) was measured for 1 h before hemorrhage. During the following 45 min, each rat was subjected to one 7-ml/kg hemorrhage every 15 min for a total of three hemorrhages. MAP was monitored by computerized data acquisition. As shown previously, MAP was slightly but significantly lower in AP-lesion rats compared with sham-lesion rats before the hemorrhage procedure. In AP-lesion rats, hemorrhage resulted in a significantly greater fall in arterial pressure than in sham-lesion rats. In spite of larger drops in pressure in AP-lesion rats, hemorrhage caused equivalent increases in plasma renin and vasopressin in both groups. In AP-lesion rats compared with sham-lesion rats, significant bradycardia was present before hemorrhage. Hemorrhage caused bradycardia in both sham- and AP-lesion rats relative to the prehemorrhage heart rates, but AP-lesion rats showed greater bradycardia than did sham-lesion rats during every time period. We conclude that the AP may play an important role in the defense of arterial pressure against hemorrhage.

scholarly journals The Effect of Subdiaphragmatic Vagotomy on Heart Rate Variability and Lung Inflammation in Rats with Severe Hemorrhagic Shock

2021 ◽  
Author(s):  
Fateme Khodadadi ◽  
Farzaneh Ketabchi ◽  
Zahra Khodabandeh ◽  
Alireza Tavassoli ◽  
Gregory F. Lewis ◽  
...  
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Hemorrhagic Shock ◽  
Hemodynamic Parameters ◽  
Sprague Dawley ◽  
Inflammatory Reactions ◽  
Sprague Dawley Rats ◽  
Tnf Α

Abstract Background The role of the sub-diaphragmatic branch of the vagus nerve in mediating heart rate variability (HRV) and inflammatory reaction to long term hemorrhagic shock has not been determined prior to this study. Methods Male Sprague-Dawley rats were divided into four groups of Sham, sub-diaphragmatic vagotomized (Vag), long term (130±2 minutes) hemorrhagic shock (LHS), and sub-diaphragmatic vagotomized with LHS (Vag+LHS). Hemodynamic parameters were recorded and HRV calculated during multiple phases of hemorrhagic shock. The expressions of TNF-α and iNOS were measured in the spleen and lung tissues at the conclusion of the protocol. Results Decreases in blood pressure during blood withdrawal were identical in the LHS and Vag+LHS groups. However, heart rate only decreased in the Nadir-1 phase of the LHS group. HRV indicated increased power in the very-low, low, and high (VLF, LF, and HF) frequency bands during the Nadir-1 phase of the LHS group and decreased power in the Vag+LHS group. There was metabolic acidosis partially compensated with respiratory system in the LHS and Vag+LHS groups. Increases of TNF-α and iNOS expression in the spleen and lung of the LHS group were reversed in the Vag+LHS group. Conclusion This study indicates that sub-diapragmatic vagotomy increases lung inflammatory reactions and blunts the cardiac vagal tone surge in response to severe hemorrhagic shock.

scholarly journals (Pro)Renin receptor regulates potassium homeostasis through a local mechanism

2017 ◽  
Vol 313 (3) ◽  
pp. F641-F656 ◽  
Author(s):  
Chuanming Xu ◽  
Aihua Lu ◽  
Hong Wang ◽  
Hui Fang ◽  
Li Zhou ◽  
...  
Keyword(s):  
Potential Role ◽  
Plasma Renin ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Local Mechanism ◽  
High K ◽  
Calcium Activated Potassium Channel ◽  
Cytochrome P 450 ◽  
Renal Expression

(Pro)renin receptor (PRR) is highly expressed in the distal nephron, but it has an unclear functional implication. The present study was conducted to explore a potential role of renal PRR during high K+ (HK) loading. In normal Sprague-Dawley rats, a 1-wk HK intake increased renal expression of full-length PRR and urinary excretion of soluble PRR (sPRR). Administration of PRO20, a decoy peptide antagonist of PRR, in K+-loaded animals elevated plasma K+ level and decreased urinary K+ excretion, accompanied with suppressed urinary aldosterone excretion and intrarenal aldosterone levels. HK downregulated Na+-Cl− cotransporter (NCC) expression but upregulated CYP11B2 (cytochrome P-450, family 11, subfamily B, polypeptide 2), renal outer medullary K+ channel (ROMK), calcium-activated potassium channel subunit α1 (α-BK), α-Na+-K+-ATPase (α-NKA), and epithelial Na+ channel subunit β (β-ENaC), all of which were blunted by PRO20. After HK loading was completed, urinary, but not plasma renin, was upregulated, which was blunted by PRO20. The same experiments that were performed using adrenalectomized (ADX) rats yielded similar results. Interestingly, spironolactone treatment in HK-loaded ADX rats attenuated kaliuresis but promoted natriuresis, which was associated with the suppressed responses of β-ENaC, α-NKA, ROMK, and α-BK protein expression. Taken together, we discovered a novel role of renal PRR in regulation of K+ homeostasis through a local mechanism involving intrarenal renin-angiotensin-aldosterone system and coordinated regulation of membrane Na+- and K+-transporting proteins.

Participation of galanin in baroreflex inhibition of heart rate by hypothalamic PVN in rat

1996 ◽  
Vol 271 (5) ◽  
pp. H1823-H1828 ◽  
Author(s):  
Y. L. Chen ◽  
S. H. Chan ◽  
J. Y. Chan
Keyword(s):  
Heart Rate ◽  
Nucleus Tractus Solitarius ◽  
Chemical Activation ◽  
Cardiovascular Regulation ◽  
Baroreceptor Reflex ◽  
Local Administration ◽  
Sprague Dawley ◽  
Pentobarbital Sodium ◽  
Sprague Dawley Rats

We investigated the role of galanin (Gal) in the suppression of baroreceptor reflex (BRR) response by the paraventricular nucleus of the hypothalamus (PVN) in adult male Sprague-Dawley rats that were anesthetized with pentobarbital sodium. Electrical stimulation (10-s train of 1-ms rectangular pulses at 20-40 microA and 10-20 Hz) of, and microinjection of L-glutamate (1 nmol) into, the PVN significantly inhibited BRR response to transient hypertension induced by phenylephrine (5 micrograms/kg iv). Such a PVN-induced BRR suppression was appreciably antagonized by local administration of Gal antiserum (1:20), but not heat-inactivated Gal antiserum (1:20), to the nucleus tractus solitarius (NTS) bilaterally. Microinjection of Gal (100 pmol) into the NTS bilaterally also resulted in a Gal antiserum-reversible inhibition of the BRR response. Immunohistochemical results demonstrated that the distribution of Gal-containing neurons in the parvocellular subnucleus of the PVN overlapped substantially with the hypothalamic loci on which electrical or chemical activation elicited suppression of the BRR response that was significantly blunted by microinjection of Gal antiserum into the NTS. These results suggest that the PVN may participate in central cardiovascular regulation by suppressing the BRR response via galaninergic neurotransmission at the NTS.

scholarly journals Mild DOCA-salt hypertension: sympathetic system and role of renal nerves

2011 ◽  
Vol 300 (5) ◽  
pp. H1781-H1787 ◽  
Author(s):  
Sachin S. Kandlikar ◽  
Gregory D. Fink
Keyword(s):  
Control Period ◽  
Whole Body ◽  
Renal Nerves ◽  
Experimental Hypertension ◽  
Sympathetic Activation ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Salt Hypertension ◽  
Hypertension Development

Excess sympathetic nervous system activity (SNA) is linked to human essential and experimental hypertension. To test whether sympathetic activation is associated with a model of deoxycorticosterone acetate (DOCA)-salt hypertension featuring two kidneys and a moderate elevation of blood pressure, we measured whole body norepinephrine (NE) spillover as an index of global SNA. Studies were conducted in chronically catheterized male Sprague-Dawley rats drinking water containing 1% NaCl and 0.2% KCl. After a 7-day surgical recovery and a 3-day control period, a DOCA pellet (50 mg/kg) was implanted subcutaneously in one group of rats (DOCA), while the other group underwent sham implantation (Sham). NE spillover was measured on control day 2 and days 7 and 14 after DOCA administration or sham implantation. During the control period, mean arterial pressure (MAP) was similar in Sham and DOCA rats. MAP was significantly increased in the DOCA group compared with the Sham group after DOCA administration ( day 14: Sham = 109 ± 5.3, DOCA = 128 ± 3.6 mmHg). However, plasma NE concentration, clearance, and spillover were not different in the two groups at any time. To determine whether selective sympathetic activation to the kidneys contributes to hypertension development, additional studies were performed in renal denervated (RDX) and sham-denervated (Sham-DX) rats. MAP, measured by radiotelemetry, was similar in both groups during the control and DOCA treatment periods. In conclusion, global SNA is not increased during the development of mild DOCA-salt hypertension, and fully intact renal nerves are not essential for hypertension development in this model.

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.

The Hepatoprotective Role of Warburgia salutaris and Iso-Mukaadial Acetate on Carbon tetrachloride Intoxicated Rats Model

2021 ◽  
Vol 17 ◽  
Author(s):  
Gideon Ayeni ◽  
Mthokozisi Blessing Cedric Simelane ◽  
Shahidul Islam ◽  
Ofentse Jacob Pooe
Keyword(s):  
Carbon Tetrachloride ◽  
Hepatic Injury ◽  
Antioxidant Properties ◽  
Hepatic Necrosis ◽  
Protective Role ◽  
Dependent Manner ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Isolated Compound

Background: Medicinal plants together with their isolated bioactive compounds are known for their antioxidant properties which constitute therapeutic agents that are routinely employed in the treatment of liver diseases. Aims of the Study: The current study sought to explore the protective role of Warburgia salutaris and its isolated compound, iso-mukaadial acetate against carbon tetrachloride (CCl4)-induced hepatic injury. Methods: Thirty-five male Sprague Dawley rats were divided into seven groups of five animals each and injected with CCl4 to induce hepatic injury. Results: Treatment with the crude extract of W. salutaris and of iso-mukaadial acetate significantly reduced the levels of alkaline phosphatase, alanine and aspartate aminotransaminases, total bilirubin and malondialdehyde in a dose dependent manner, when compared to untreated groups. Liver histology revealed a reduction in hepatic necrosis and inflammation. Conclusion: The current investigation has demonstrated that W. salutaris extract and iso-mukaadial acetate could mitigate the acute liver injury inflicted by a hepatotoxic inducer in rats.

Renal denervation alters cardiovascular and endocrine responses to hemorrhage in conscious newborn lambs

1998 ◽  
Vol 275 (1) ◽  
pp. H285-H291 ◽  
Author(s):  
Francine G. Smith ◽  
Isam Abu-Amarah
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Renal Denervation ◽  
Plasma Renin ◽  
Sympathetic Nerves ◽  
Renal Nerves ◽  
Elevated Plasma ◽  
Baseline Levels ◽  
Renal Sympathetic

To investigate the role of renal sympathetic nerves in modulating cardiovascular and endocrine responses to hemorrhage early in life, we carried out three experiments in conscious, chronically instrumented lambs with intact renal nerves (intact; n = 8) and with bilateral renal denervation (denervated; n = 5). Measurements were made 1 h before and 1 h after 0, 10, and 20% hemorrhage. Blood pressure decreased transiently after 20% hemorrhage in intact lambs and returned to control levels. In denervated lambs, however, blood pressure remained decreased after 60 min. After 20% hemorrhage, heart rate increased from 170 ± 16 to 207 ± 18 beats/min in intact lambs but not in denervated lambs, in which basal heart rates were already elevated to 202 ± 21 beats/min. Despite an elevated plasma renin activity (PRA) measured in denervated (12.0 ± 6.4 ng ANG I ⋅ ml−1 ⋅ h−1) compared with intact lambs (4.0 ± 1.1 ng ANG I ⋅ ml−1 ⋅ h−1), the increase in PRA in response to 20% hemorrhage was similar in both groups. Plasma levels of arginine vasopressin increased from 11 ± 8 to 197 ± 246 pg/ml after 20% hemorrhage in intact lambs but remained unaltered in denervated lambs from baseline levels of 15 ± 10 pg/ml. These observations provide evidence that in the newborn, renal sympathetic nerves modulate cardiovascular and endocrine responses to hemorrhage.

scholarly journals Transient Neonatal Cryptosporidium parvum Infection Triggers Long-Term Jejunal Hypersensitivity to Distension in Immunocompetent Rats

2006 ◽  
Vol 74 (7) ◽  
pp. 4387-4389 ◽  
Author(s):  
Rachel Marion ◽  
Asiya Baishanbo ◽  
Gilles Gargala ◽  
Arnaud François ◽  
Philippe Ducrotté ◽  
...  
Keyword(s):  
Cryptosporidium Parvum ◽  
Myeloperoxidase Activity ◽  
Sprague Dawley ◽  
Depressor Response ◽  
Sprague Dawley Rats

ABSTRACT In 5-day-old immunocompetent Sprague-Dawley rats infected with either 102 or 105 Cryptosporidium parvum oocysts, transient infection resulted 120 days later in increased cardiovascular depressor response to jejunal distension and jejunal myeloperoxidase activity (P < 0.05). Nitazoxanide treatment normalized jejunal sensitivity (P < 0.001) but not myeloperoxidase levels (P > 0.05). Data warrant further evaluation of the role of early cryptosporidiosis in the development of chronic inflammatory gut conditions.

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