Lesions of A1 noradrenergic cells affect AVP release and heart rate during hemorrhage

1987 ◽  
Vol 253 (5) ◽  
pp. H1012-H1017 ◽  
Author(s):  
G. A. Head ◽  
A. W. Quail ◽  
R. L. Woods
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Blood Volume ◽  
Ventrolateral Medulla ◽  
Sham Operation ◽  
Noradrenergic Neurons ◽  
Reflex Tachycardia ◽  
Conscious Rabbits ◽  
Plasma Arginine

The role of A1 noradrenergic cells of the ventrolateral medulla in the changes in mean arterial pressure (MAP), heart rate (HR), and plasma arginine vasopressin (AVP) after slow continuous hemorrhage (2% blood vol/min up to 35%) was examined by comparing responses in conscious rabbits before and 3 wk after a sham operation or A1 lesions. In the control experiments, MAP fell minimally up to the withdrawal of 20% of blood volume after which it fell abruptly to 20-30 mmHg below control by the 35% level. Plasma AVP increased nonlinearly during progressive hemorrhage with significant increases occurring only after 25% of blood volume was removed. In contrast, HR increased linearly after the onset of bleeding. After A1 lesions, which destroyed 84% (range 80-94%) of the noradrenergic cells, the amount of AVP released and the tachycardia during hemorrhage were reduced by 83 and 61%, respectively (P less than 0.005), but the fall in MAP was minimally affected. Basal values of MAP, HR, or plasma AVP were not affected by the lesions. These results suggest that during hemorrhage in conscious rabbits A1 noradrenergic neurons are important for the secretion of AVP and the reflex tachycardia but play little role in the maintenance of blood pressure.

scholarly journals Role of the Anesthetic Determine the Clonidine Effects Mediated by RVLM/-α2-Adrenoceptors on Blood Pressure and Heart Rate in Rats

2018 ◽  
Vol 12 (1) ◽  
pp. 64-78
Author(s):  
Imad Hatim Rashid
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Wistar Rats ◽  
Hypotensive Effect ◽  
Ventrolateral Medulla ◽  
Α2 Adrenoceptors ◽  
Caudal Pressor ◽  
Α2 Receptors ◽  
Stimulation Of

To examine the hypothesis of a role for α2-adrenoceptors in mediating the mechanism of urethane hypotensive effect whether it's peripheral or central, Wistar rats were anesthetized with urethane or (for comparison) with halothane, to study the influence of urethane that govern the mechanism of central and peripheral α2-adrenoceptors action, on basal BP & HR, and the rise in blood pressure (BP) to the stimulation of caudal pressor area (CPA), when these receptors were either centrally activated by bilateral rostral ventrolateral medulla (RVLM) microinjection of clonidine (30nM), and blockade with any of the clonidine antagonists, yohimbine (500pmol/50nl), and idazoxane (270nM) or yohimbine+idazoxane,  or when peripherally activated (of urethane anesthetized rats) by i.v. clonidine (100nmol/kg), which also blockade with idazoxane or yohimbine+idazoxane. The results indicated presence of no anesthetic differences in a partial involvement of α2-receptors-RVLM, vs. a complete involvement of I(1)-imidazole receptors in mediating the hypotensive effects of clonidine. It also indicates α2-/I(1)-receptors synergism in raising the urethane lowering of baseline of SBP to the levels of control or halothane group. In conclusion, the result suggests involvement both of the central and the peripheral α2-adrenoceptors in mediating urethane hypotensive effects.

Blood Volume and the Carotid Baroreceptor Reflex in Conscious Rabbits

1981 ◽  
Vol 61 (s7) ◽  
pp. 173s-175s ◽  
Author(s):  
J. Ludbrook ◽  
I. B. Faris ◽  
G. G. Jamieson
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Cardiac Output ◽  
Systemic Vascular Resistance ◽  
Blood Volume ◽  
Vascular Resistance ◽  
Baroreceptor Reflex ◽  
Phase Lag ◽  
Carotid Baroreceptor ◽  
Conscious Rabbits

1. The effects of acute blood volume change in conscious rabbits on a.c. gain of the carotid baroreceptor reflex with respect to heart rate, blood pressure, cardiac output and systemic vascular resistance were studied. 2. With acute, isohaemic increase in blood volume by 20% and 40% the only consistent trend was a decrease in gain for systemic vascular resistance. 3. With acute reduction in blood volume there was a consistent tendency for gain for heart rate to fall. With 20% reduction in blood volume, gain for cardiac output fell but gain for systemic vascular resistance rose and its phase-lag became shorter, so that gain for blood pressure was unaltered. The enhanced gain for systemic vascular resistance was not sustained with 35% reduction in blood volume, so that gain for blood pressure fell. 4. Thus control of blood pressure by the carotid sinus reflex is remarkably unaffected by acute change in blood volume, and is impaired only when there is depression of gain for cardiac output without a concomitant rise in gain for systemic vascular resistance.

Pre-emptive Analgesia for Postoperative Pain Relief in Children – Role of Paracetamol

2009 ◽  
pp. 9-16
Author(s):  
Rubina Yasmin ◽  
AKM Akhtaruzzaman ◽  
Paresh Chandra Sarker ◽  
Neaz Ahmed ◽  
Ranadhir Kumar Kundu ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Postoperative Pain ◽  
Diclofenac Sodium ◽  
Total Duration ◽  
Pain Scale ◽  
Prospective Clinical Study ◽  
High Dose ◽  
Induction Of Anaesthesia

This prospective clinical study was carried out in the Dept. of Anaesthesia, Analgesia and Intensive Care Medicine, BSMMU, Dhaka, during the period of May 2003 to July 2003. The study was done to emphasize the importance of giving analgesics preemptively instead of waiting for the child to complain of pain and to produce smooth recovery after surgery by decreasing immediate postoperative pain in children by a simple, safe acceptable drug. The children scheduled for tonsillectomy under general anaesthesia were recruited in this study. The analgesic efficiency of rectal paracetamol in two doses, 25 mg/kg bodywt.(Gr-P25) and 50 mg/kg. bodywt. (Gr-P50) were compared with Diclofenac Sodium suppository 1mg/ kg body weight (Gr-D) given half an hour before induction of anaesthesia. Pain scoring was done by TPPPS (Toddler Pre-schooler postoperative pain scale). Heart rate and blood pressure were stable in Gr-P50 and Gr-D. Time of first demand of analgesic was delayed in Gr-P50 and Gr-D. Total paracetamol consumption in 24 hours was less in Gr-P50(181±14.25) and Gr-D (212±25) than Gr-P25(318± 26.39). Total duration of analgesia in Gr- P50 (657±9.94) mins. and in Gr- D(502±10.63) mins. and in Gr-P25(288±23.17) mins. Pre-emptive high dose rectal paracetamol appears to be more effective than diclofenac sodium suppository for postoperative analgesia in children undergoing tonsillectomy. Journal of BSA, Vol. 18, No. 1 & 2, 2005 p.9-16

Increased Pressor Responsiveness to Enkephalin in Spontaneously Hypertensive Rats: The Role of Vasopressin

1980 ◽  
Vol 59 (s6) ◽  
pp. 235s-237s ◽  
Author(s):  
R. W. Rockhold ◽  
J. T. Crofton ◽  
L. Share
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Pressor Response ◽  
Cardiovascular Effects ◽  
Hypertensive Rats ◽  
Methionine Enkephalin ◽  
Spontaneously Hypertensive ◽  
Wistar Kyoto Rats ◽  
Wistar Kyoto

1. The cardiovascular effects of an enkephalin analogue were examined in spontaneously hypertensive and normotensive Wistar-Kyoto rats. (D-Ala2)-methionine enkephalin caused a biphasic increase in blood pressure and an increase in heart rate after intracerebroventricular injection. 2. The initial pressor response to (D-Ala2)-methionine enkephalin was greater in hypertensive than in normotensive rats. No difference was noted between groups during the secondary pressor response. Heart rate increases paralleled the secondary increase in blood pressure. 3. Naloxone pretreatment abolished the secondary increase in blood pressure and the tachycardia, but did not blunt the initial pressor response in female Wistar-Kyoto rats. 4. Plasma levels of arginine vasopressin were depressed during the plateau phase of the pressor response in hypertensive rats given intracerebroventricular (d-Ala2)-methionine enkephalin. 5. The results suggest that the cardiovascular effects of central enkephalin are not due to vasopressin, but may involve activation of the sympathetic nervous system.

scholarly journals Role of the medulla oblongata in normal and high arterial blood pressure regulation: the contribution of Escola Paulista de Medicina - UNIFESP

2009 ◽  
Vol 81 (3) ◽  
pp. 589-603 ◽  
Author(s):  
Sergio L. Cravo ◽  
Ruy R. Campos ◽  
Eduardo Colombari ◽  
Mônica A. Sato ◽  
Cássia M. Bergamaschi ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Arterial Blood Pressure ◽  
Medulla Oblongata ◽  
Neural Circuits ◽  
Ventrolateral Medulla ◽  
Vasomotor Tone ◽  
Arterial Blood ◽  
Pathological Conditions ◽  
De Medicina

Several forms of experimental evidence gathered in the last 37 years have unequivocally established that the medulla oblongata harbors the main neural circuits responsible for generating the vasomotor tone and regulating arterial blood pressure. Our current understanding of this circuitry derives mainly from the studies of Pedro Guertzenstein, a former student who became Professor of Physiology at UNIFESP later, and his colleagues. In this review, we have summarized the main findings as well as our collaboration to a further understanding of the ventrolateral medulla and the control of arterial blood pressure under normal and pathological conditions.

scholarly journals Rostral ventral medulla 5-HT1A receptors selectively inhibit the somatosympathetic reflex

2001 ◽  
Vol 280 (5) ◽  
pp. R1261-R1268 ◽  
Author(s):  
Takashi Miyawaki ◽  
Ann K. Goodchild ◽  
Paul M. Pilowsky
Keyword(s):  
Blood Pressure ◽  
Arterial Blood Pressure ◽  
Sympathetic Nerve Activity ◽  
Selective Inhibition ◽  
Inhibitory Effect ◽  
Ventrolateral Medulla ◽  
Arterial Blood ◽  
Potent Inhibition ◽  
Somatosympathetic Reflex

The role of the 5-hydroxytryptamine (5-HT1A) receptors in the rostral ventrolateral medulla (RVLM) on somatosympathetic, baroreceptor, and chemoreceptor reflexes was examined in anesthetized rats. Microinjection of the selective 5-HT1A agonist 8-hydroxy-di- n-propylamino tetralin (8-OH-DPAT) decreased arterial blood pressure and splanchnic sympathetic nerve activity (SNA). Electrical stimulation of the hindlimb evoked early and late excitatory sympathetic responses. Bilateral microinjection in the RVLM of 8-OH-DPAT markedly attenuated both the early and late responses. This potent inhibition of the somatosympathetic reflex persisted even after SNA and arterial blood pressure returned to preinjection levels. Preinjection of the selective 5-HT1A antagonist NAN-190 in the RVLM blocked the sympathoinhibitory effect of 8-OH-DPAT and attenuated the inhibitory effect on the somatosympathetic reflex. 8-OH-DPAT injected in the RVLM did not affect baroreceptor or chemoreceptor reflexes. Our findings suggest that activation of 5-HT1A receptors in the RVLM exerts a potent, selective inhibition on the somatosympathetic reflex.

Leukocyte kinetics in the human lung: role of exercise and catecholamines

1984 ◽  
Vol 57 (3) ◽  
pp. 711-719 ◽  
Author(s):  
A. L. Muir ◽  
M. Cruz ◽  
B. A. Martin ◽  
H. Thommasen ◽  
A. Belzberg ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Peripheral Blood ◽  
Human Lung ◽  
Work Load ◽  
Low Flow ◽  
Epinephrine Infusion ◽  
First Pass ◽  
Pass Through

In six normal supine subjects epinephrine infusion produced a greater leukocytosis with smaller changes in heart rate and blood pressure than did norepinephrine or isoproterenol. Upright exercise in those subjects produced a greater leukocytosis than supine exercise at the same work load. To determine the lung's participation in these events, indium-labeled neutrophils (PMN) were given to four of the subjects. We found that 20–25% were retained in the first pass through the lung when compared with technetium-labeled erythrocytes. The number of labeled PMN in the lung gradually decreased and the number in the spleen and the liver increased. Exercise and catecholamine infusion caused an acceleration in the release of labeled cells from the lung, an increase in both labeled and unlabeled cells in the peripheral blood, and an increase in the number of labeled cells in the liver and spleen. This suggests that increased perfusion of low-flow areas in the lung may contribute to the increased leukocytosis seen in association with both exercise and catecholamine infusion.

Role of Screening Tests in the Detection and Management of Blood Pressure Abnormalities Among Young Population

Angiology ◽  
2016 ◽  
Vol 68 (5) ◽  
pp. 441-446 ◽  
Author(s):  
Mehmet Karaduman ◽  
Mustafa Aparci ◽  
Murat Unlu ◽  
Cengiz Ozturk ◽  
Sevket Balta ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Cardiovascular Disease ◽  
Body Mass Index ◽  
Heart Rate ◽  
Medical Records ◽  
Screening Tests ◽  
Young Population ◽  
Males And Females ◽  
Apparently Healthy

The prevalence of hypertension is increasing among young population worldwide. So there is an interest in detecting prehypertension and hypertension in childhood. We determined blood pressure (BP) recorded at a screening test in a young population. We retrospectively evaluated the medical records including systolic blood pressure (SBP), diastolic blood pressure (DBP), weight, height, and body mass index (BMI) of 685 male and 130 female apparently healthy adolescents. We evaluated the prevalence of BP categories: normotension, prehypertension, and hypertension. The prevalence of normotension (n = 369), prehypertension (n = 333), and hypertension (n = 113) was 45.3%, 40.9% and 13.9%, respectively; prehypertension and hypertension were significantly higher among males. The prevalence of prehypertension and hypertension was significantly higher among overweight males and females. The BMI significantly correlated with SBP, DBP, and heart rate among both genders. The prevalence of prehypertension and hypertension is high among Turkish adolescents. Screening tests focused on BP and BMI measurement may help detect the young population at risk of hypertension and cardiovascular disease in the future.

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.

Blood pressure regulation by ETA and ETB receptors in conscious, telemetry-instrumented mice and role of ETA in hypertension produced by selective ETB blockade

2006 ◽  
Vol 290 (6) ◽  
pp. H2554-H2559 ◽  
Author(s):  
Ryan M. Fryer ◽  
Pamela A. Rakestraw ◽  
Patricia N. Banfor ◽  
Bryan F. Cox ◽  
Terry J. Opgenorth ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Blood Pressure Regulation ◽  
Pressure Regulation ◽  
Type B ◽  
Selective Antagonist ◽  
Relevant Role ◽  
Basal Blood Pressure ◽  
Baseline Values

The net contribution of endothelin type A (ETA) and type B (ETB) receptors in blood pressure regulation in humans and experimental animals, including the conscious mouse, remains undefined. Thus we assessed the role of ETA and ETB receptors in the control of basal blood pressure and also the role of ETA receptors in maintaining the hypertensive effects of systemic ETB blockade in telemetry-instrumented mice. Mean arterial pressure (MAP) and heart rate were recorded continuously from the carotid artery and daily (24 h) values determined. At baseline, MAP ranged from 99 ± 1 to 101 ± 1 mmHg and heart rate ranged between 547 ± 15 and 567 ± 19 beats/min ( n = 6). Daily oral administration of the ETB selective antagonist A-192621 [10 mg/kg twice daily] increased MAP to 108 ± 1 and 112 ± 2 mmHg on days 1 and 5, respectively. Subsequent coadministration of the ETA selective antagonist atrasentan (5 mg/kg twice daily) in conjunction with A-192621 (10 mg/kg twice daily) decreased MAP to baseline values on day 6 (99 ± 2 mmHg) and to below baseline on day 8 (89 ± 3 mmHg). In a separate group of mice ( n = 6) in which the treatment was reversed, systemic blockade of ETB receptors produced no hypertension in animals pretreated with atrasentan, underscoring the importance of ETA receptors to maintain the hypertension produced by ETB blockade. In a third group of mice ( n = 10), ETA blockade alone (atrasentan; 5 mg/kg twice daily) produced an immediate and sustained decrease in MAP to values below baseline (baseline values = 101 ± 2 to 103 ± 2 mmHg; atrasentan decreased pressure to 95 ± 2 mmHg). Thus these data suggest that ETA and ETB receptors play a physiologically relevant role in the regulation of basal blood pressure in normal, conscious mice. Furthermore, systemic ETB receptor blockade produces sustained hypertension in conscious telemetry-instrumented mice that is absent in mice pretreated with an ETA antagonist, suggesting that ETA receptors maintain the hypertension produced by ETB blockade.

Sign in / Sign up

Export Citation Format

Share Document