scholarly journals Reflex cardiovascular response to brief abdominal visceral ischemia is mediated in part by prostaglandins

1999 ◽  
Vol 277 (5) ◽  
pp. H1793-H1798 ◽  
Author(s):  
Premjit S. Chahal ◽  
Stephen V. Rendig ◽  
John C. Longhurst
Keyword(s):  
Blood Pressure ◽  
Acetylsalicylic Acid ◽  
Arterial Blood Pressure ◽  
Cardiovascular Response ◽  
Reflex Response ◽  
Visceral Ischemia ◽  
Arterial Blood ◽  
Group 3 ◽  
Group 2 ◽  
Group 1

Prostaglandin concentrations are elevated in intestinal lymph during brief abdominal visceral ischemia, and exogenously applied prostaglandins can directly stimulate or sensitize ischemically sensitive visceral sympathetic nerve fibers. However, it is not known if prostaglandin production during abdominal ischemia is sufficient to contribute to the reflex cardiovascular response (e.g., hypertension). Accordingly, in anesthetized cats, the femoral artery was cannulated for measurement of arterial blood pressure, and the superior mesenteric and celiac arteries were isolated and fitted with snare occluders. After dual occlusion of these arteries (≤20 min), the cyclooxygenase inhibitors indomethacin (10–20 mg/kg iv, n = 5, group 1) or acetylsalicylic acid [50 mg/kg iv ( n = 6) and ia ( n = 2); group 2] were administered and ischemia was repeated. In group 1, indomethacin lowered the reflex arterial blood pressure increment by 39% from 31 ± 7 to 19 ± 5 mmHg ( P > 0.05). In group 2, acetylsalicylic acid significantly ( P < 0.05) reduced the reflex rise in blood pressure by 46% (28 ± 3 to 15 ± 4 mmHg). A second, more invasive preparation ( group 3) was utilized to 1) minimize the confounding, transient, nonreflex rise in blood pressure associated with arterial ligation, and 2) further assess the inhibitory effect of indomethacin. In group 3, the ischemia-induced blood pressure rise of 28 ± 6 mmHg was reduced by 43% to 16 ± 4 mmHg after indomethacin ( n = 4, P < 0.05). Thus blockade of the cyclooxygenase pathway by two structurally dissimilar inhibitors attenuated the visceral-cardiovascular reflex response to brief ischemia, suggesting that prostaglandins released during visceral ischemia contribute significantly to the activation of the reflex cardiovascular response.

scholarly journals Evaluation of the Accuracy of the Delta Life DL 1000 Oscillometric Monitor for Blood Pressure Measurement in Anesthetized Dogs of Different Weight Ranges

2020 ◽  
Vol 48 ◽  
Author(s):  
Bárbara Silva Correia ◽  
Eduardo Raposo Monteiro ◽  
João Victor Barbieri Ferronatto ◽  
Luciana Branquinho Queiroga ◽  
José Ricardo Herrera Becerra
Keyword(s):  
Blood Pressure ◽  
Arterial Blood Pressure ◽  
Pressure Measurement ◽  
Elective Surgery ◽  
Blood Pressure Measurement ◽  
Measurement Data ◽  
Arterial Blood ◽  
Anesthetized Dogs ◽  
Group 2 ◽  
Group 1

Background: Arterial blood pressure is one of the most commonly variables monitored during anesthetic procedures in veterinary patients. The most reliable method for measuring arterial blood pressure in dogs and cats is the direct (invasive) method. However, the oscillometric method is less complex and more practical for clinical routine in small animals. Nevertheless, oscillometric monitors present great variability in accuracy. The present study aimed to determine the accuracy of the Delta Life DL 1000 oscillometric monitor for measurement of systolic, mean and diastolic blood pressures (SAP, MAP and DAP, respectively) in anesthetized dogs of different weight ranges.Materials, Methods & Results: This study was approved by the Institutional Ethics Committee of Animal Use. Fifteen female dogs of different breeds, weighing 11.6 ± 10.0 kg and with a mean age of 48 ± 51 months were used. All animals were scheduled for elective surgery under general anesthesia in the Institution Veterinary Hospital. Dogs were anesthetized with morphine, propofol and isoflurane and had one 20 or 22 gauge catheter introduced into the dorsal pedal artery for continuous, invasive monitoring of SAP, MAP and DAP. A blood pressure cuff was positioned over the middle third of the radius and connected to Delta Life DL 1000 monitor. Oscillometric readings of SAP, MAP and DAP were registered every 5 minutes, and invasive values were simultaneously recorded. Values obtained with both methods were compared (invasive versus oscillometric) by use of the Bland Altman method to determine the bias, standard deviation of bias and 95% limits of agreement. The percentages of errors between the methods within 10 mmHg and within 20 mmHg were calculated. The results obtained were compared with the criteria from the American College of Veterinary Internal Medicine (ACVIM) for validation of indirect methods of arterial blood pressure measurement. Data were stratified into two groups according to the weight: < 10 kg (Group 1; n = 9); and ≥ 10 kg (Group 2; n = 6). In Group 1, 119 paired measurements were obtained, four of which classified as hypotension (SAP < 90 mmHg), 98 as normotension (SAP from 90 to 140mmHg) and 17 as hypertension (SAP > 140 mmHg). Bias (± SD) values in Group 1 were as follows: SAP, 5.2 ± 18.1 mmHg; MAP, -3.4 ± 17.2 mmHg; and DAP, 12.0 ± 17.5 mmHg. The percentages of errors within 10 mmHg were 40.3% for SAP; 45.4% for MAP and 28.6% for DAP. The percentages of errors within 20 mmHg were 72.3% for SAP, 84.0% for MAP and 68.1% for DAP. In Group 2, 66 paired measurements were obtained, nine of which classified as hypotension, 56 as normotension and one as hypertension. Bias (± SD) in Group 2 were as follows: SAP, 13.6 ± 14.3 mmHg; MAP, -1.1 ± 13.5 mmHg; and DAP, 8.2 ± 16.0 mmHg. The percentages of errors within 10 mmHg were 33.3% for SAP, 77.3% for MAP and 33.3% for DAP. The percentages of errors within 20 mmHg were 65.1% for SAP, 92.4% for MAP and 83.4% for DAP.Discussion: Based on the results of this study and reference criteria from the ACVIM, the Delta Life DL 1000 monitor had a poor accuracy for SAP, MAP and DAP and did not meet the criteria from the ACVIM in anesthetized dogs under 10 kg. Measurements of MAP in dogs ≥ 10 kg met the ACVIM criteria, but measurements of SAP and DAP did not. Based on the findings in this study, the DL 1000 oscillometric monitor is not recommended for blood pressure measurement in anesthetized dogs < 10 kg. In dogs ≥ 10 kg, measurements of MAP yielded acceptable values, but SAP and DAP measurements did not.

scholarly journals Glycopenia - induced sympathoadrenal activation in diabetes mellitus and uncontrolled arterial hypertension: an observational study

2020 ◽  
Vol 12 (1) ◽  
Author(s):  
Abimbola Abobarin-Adeagbo ◽  
Andreas Wienke ◽  
Matthias Girndt ◽  
Rainer U. Pliquett
Keyword(s):  
Blood Pressure ◽  
Arterial Hypertension ◽  
Insulin Dose ◽  
Hypertensive Crisis ◽  
Plasma Norepinephrine ◽  
Arterial Blood ◽  
Group 3 ◽  
Group 2 ◽  
Group 1 ◽  
Diabetes Patients

Abstract Background Aim of this study is to investigate a possible association of hypoglycemic episodes and arterial hypertension. We hypothesize that hospitalized insulin-treated diabetes patients with hypertensive crisis have more hypoglycemic episodes than their counterparts without hypertensive crisis on admission. Methods In a prospective, observational cohort study, 65 insulin-treated diabetes patients (type 1, type 2, type 3c) were included in Group 1, when a hypertensive crisis was present, as control patients in Group 2 without hypertensive crisis or hypoglycemia, in Group 3, when a symptomatic hypoglycemia was present on admission. All patients were subjected to open-label continuous glucose monitoring, 24-h blood-pressure- and Holter electrocardiogram recordings, and to laboratory tests including plasma catecholamines. Results 53 patients, thereof 19 Group-1, 19 Group-2, 15 Group-3 patients, completed this study. Group-1 patients had the highest maximum systolic blood pressure, a higher daily cumulative insulin dose at admission, a higher body-mass index, and a higher plasma norepinephrine than control patients of Group 2. Group-3 patients had more documented hypoglycemic episodes (0.8 ± 0.5 per 24 h) than Group-2 patients (0.2 ± 0.3 per 24 h), however, they were not different to the ones in Group-1 patients (0.4 ± 0.4 per 24 h). Plasma norepinephrine and mean arterial blood pressure were higher Group-1 and Group-3 patients than in control patients of Group 2. At discharge, the daily cumulative insulin dose was reduced in Group-1 (− 18.4 ± 24.9 units) and in Group-3 patients (− 18.6 ± 22.7 units), but remained unchanged in Group-2 control patients (− 2.9 ± 15.6 units). Conclusions An association between hypoglycemic events and uncontrolled hypertension was found in this study.

scholarly journals Glycopenia-Induced Sympathoadrenal Activation in Diabetes Mellitus And Uncontrolled Arterial Hypertension: An Observational Study.

2020 ◽  
Author(s):  
Abimbola Abobarin-Adeagbo ◽  
Andreas Wienke ◽  
Matthias Girndt ◽  
Rainer U. Pliquett
Keyword(s):  
Blood Pressure ◽  
Arterial Hypertension ◽  
Insulin Dose ◽  
Hypertensive Crisis ◽  
Plasma Norepinephrine ◽  
Arterial Blood ◽  
Group 3 ◽  
Group 2 ◽  
Group 1 ◽  
Diabetes Patients

Abstract Background: Aim of this study is to investigate a possible association of hypoglycemic episodes and arterial hypertension. We hypothesize that hospitalized insulin-treated diabetes patients with hypertensive crisis have more hypoglycemic episodes than their counterparts without hypertensive crisis on admission.Methods: In a prospective, observational cohort study, 65 insulin-treated diabetes patients (type 1, type 2, type 3c) were included in Group 1, when a hypertensive crisis was present, as control patients in Group 2 without hypertensive crisis or hypoglycemia, in Group 3, when a symptomatic hypoglycemia was present on admission. All patients were subjected to open-label continuous flash glucose monitoring, to 24-hour blood-pressure and Holter electrocardiogram recordings, and to laboratory tests including plasma catecholamines. Results: 53 patients, thereof 19 Group-1, 19 Group-2, 15 Group-3 patients, completed this study. Group-1 patients had the highest maximum systolic blood pressure, a higher daily cumulative insulin dose at admission, a higher body-mass index, and a higher plasma norepinephrine than control patients of Group 2. Group-3 patients had more documented hypoglycemic episodes (0.8 ± 0.5 per 24 hours) than Group-2 patients (0.2 ± 0.3 per 24 hours), however, they were not different to the ones in Group-1 patients (0.4 ± 0.4 per 24 hours). Plasma norepinephrine and mean arterial blood pressure were not different between Group-1 and Group-3 patients, though higher than in Group-2 patients. At discharge, the daily cumulative insulin dose was reduced in Group-1 (-18.4 ± 24.9 units) and Group-3 patients (-18.6 ± 22.7 units), but remained unchanged in Group-2 patients (-2.9 ± 15.6 units).Conclusions: An association between hypoglycemic events and uncontrolled hypertension was found in this study.

Dietary linoleic acid deprivation: effects on blood pressure and PGI2 synthesis

1983 ◽  
Vol 244 (2) ◽  
pp. H228-H233
Author(s):  
R. Dusing ◽  
R. Scherhag ◽  
K. Glanzer ◽  
U. Budde ◽  
H. J. Kramer
Keyword(s):  
Blood Pressure ◽  
Arachidonic Acid ◽  
Linoleic Acid ◽  
Arterial Blood Pressure ◽  
Aortic Tissue ◽  
Dietary Linoleic Acid ◽  
Arterial Blood ◽  
Isolated Aorta ◽  
Group 2 ◽  
Group 1

The possible role of arachidonic acid metabolites in the regulation of arterial blood pressure was investigated in rats receiving 0, 5, or 9 energy (en) % linoleic acid in their diet (groups 1-3) over 6 wk. In group 1 animals, systolic arterial blood pressure significantly increased from 100.5 +/- 2.0 to 110.6 +/- 3.1 mmHg (P less than 0.01) after 6 wk of dietary linoleic acid deprivation, whereas no effect on blood pressure was observed in group 2 and 3 animals receiving dietary linoleic acid supplements. Generation of prostacyclin (PGI2)-like activity by isolated aorta from rats fed the different diets was determined using a platelet-aggregation bioassay following incubation of aortic tissue for 12, 15, and 30 min, respectively. In isolated aorta from rats fed the 5 en% linoleic acid, production of PGI2 was 55.9 +/- 1.2, 70.5 +/- 2.6, and 90.9 +/- 3.6 pmol/mg over the three incubation periods. In group 1 animals, a significant suppression of PGI2 generation to 35.4 +/- 1.5, 41.1 +/- 1.7, and 55.0 +/- 1.2 pmol/mg (P less than 0.005) was observed, whereas PGI2 production was unaltered in aortic tissue from group 3 animals. In contrast, plasma concentrations of circulating thromboxane B2 were highest in group 1 animals (2.15 +/- 0.38 pmol/ml) and measured 1.28 +/- 0.17 and 0.83 +/- 0.10 pmol/ml in group 2 and 3 animals, respectively. Our results demonstrate that dietary deprivation of the arachidonic acid precursor linoleic acid increases arterial blood pressure that is associated with a suppression of vascular PGI2 synthesis and, most likely, a secondary rise in circulating thromboxane concentrations.

Intracranial Pressure and Cerebral Hemodynamic in Patients with Cerebral Tumors

2003 ◽  
Vol 98 (2) ◽  
pp. 329-336 ◽  
Author(s):  
Kurt D. Petersen ◽  
Uffe Landsfeldt ◽  
Georg Emil Cold ◽  
Carsten B. Petersen ◽  
Søren Mau ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Blood Pressure ◽  
Oxygen Saturation ◽  
Arterial Blood Pressure ◽  
Mean Arterial Blood Pressure ◽  
Jugular Vein ◽  
Arterial Blood ◽  
Group 3 ◽  
Carbon Dioxide Reactivity ◽  
Group 1

Background A critical point during craniotomy is opening of dura, where a high intracranial pressure (ICP) results in swelling of cerebral tissue. Controlled studies concerning ICP, degree of dural tension, and degree of cerebral swelling are therefore warranted. Methods In an open-label study, 117 patients with supratentorial cerebral tumors were randomized to propofol-fentanyl (group 1), isoflurane-fentanyl (group 2), or sevoflurane-fentanyl anesthesia (group 3). Normo- to moderate hypocapnia was applied, with a target level of arterial carbon dioxid tension of 30-40 mmHg. Mean arterial blood pressure was stabilized with intravenous ephedrine (2.5-5 mg) if necessary. Subdural ICP, mean arterial blood pressure, cerebral perfusion pressure (CPP), arteriovenous oxygen difference (AVDo2), internal jugular vein oxygen saturation were monitored before and after a 10-min period of hyperventilation, and the carbon dioxide reactivity was calculated. Furthermore, the tension of dura before and during hyperventilation and the degree of cerebral swelling during hyperventilation and after opening of the dura were estimated by the neurosurgeon. Results No differences were found between groups with regard to demographics, neuroradiologic examination, positioning of the head, and time to ICP measurement. Before and during hyperventilation, ICP was significantly lower and mean arterial blood pressure and CPP significantly higher in group 1 compared with groups 2 and 3 (P &lt; 0.05). The tension of dura before and during hyperventilation was significantly lower in group 1 compared with group2 (P &lt; 0.05), but not significantly different from group 3. In group 1, cerebral swelling after opening of dura was significantly lower compared with groups 2 and 3 (P &lt; 0.05). Furthermore, AVDo was significantly higher and jugular vein oxygen saturation and carbon dioxide reactivity were significantly lower in group 1 compared with groups 2 and 3 (P &lt; 0.05). No significant differences with regard to ICP, CPP, AVDo, carbon dioxide reactivity, and jugular vein oxygen saturation were found between patients anesthetized with isoflurane and sevoflurane. Conclusions The study indicates that before as well as during hyperventilation, subdural ICP and AVDo2 are lower and CPP higher in propofol-anesthetized patients compared with patients anesthetized with isoflurane or sevoflurane. These findings were associated with less tendency for cerebral swelling after opening of dura in the propofol group. The carbon dioxide reactivity in patients anesthetized with isoflurane and sevoflurane was significantly higher than in the propofol group. The differences in subdural ICP between the groups are presumed to be caused by differences in the degree of vasoconstriction elicited by the anesthetic agents, but autoregulatory mechanisms caused by differences in CPP cannot be excluded.

scholarly journals Effect of clonidine and gabapentin as oral premedication on hemodynamic response to laryngoscopy and tracheal intubation

2018 ◽  
Vol 6 (12) ◽  
pp. 3819
Author(s):  
Prabhati R. Mishra ◽  
Manmaya Padhy ◽  
Rusikesh Satapathy ◽  
Monali Kar
Keyword(s):  
Blood Pressure ◽  
Endotracheal Intubation ◽  
Hemodynamic Response ◽  
Oral Clonidine ◽  
Arterial Blood ◽  
Induction Group ◽  
Group 3 ◽  
Group 2 ◽  
Oral Premedication ◽  
Group 1

Background: Laryngoscopy and endotracheal intubation causes stimulation of symphatho-adrenal system resulting in increase in blood pressure and heart rate. The present study compared oral clonidine, gabapentin and placebo premedication in attenuating haemodynamic response to laryngoscopy and endotracheal intubation.Methods: About 90 adult patients of ASA grade I and II patients in age group of 18-60 yrs, of either sex posted for surgery under general anaesthesia were randomly divided into three groups (30 patients in each group). The study drugs were given orally 90minutes before induction. Group 1 and Group 2 were pre treated with oral clonidine (0.2mg) and gabapentin (800mg) respectively and Group-3 received placebo. The HR, systolic blood pressure, diastolic blood pressure and mean arterial blood pressure were recorded before induction of anesthesia and 1, 3, 5, 10min after laryngoscopy and intubation.Results: It was found that both clonidine and gabapentin reduces HR, SBP, DBP, MAP than placebo group at lminute, 3minutes, 5minutes and 10minutes after intubation. But reduction is more with clonidine as compared to gabapentine and difference was statistically significant (P = <0.0001).Conclusions: Both oral clonidine and gabapentine attenuate hemodynamic response to laryngoscopy and endotracheal intubation but effect is better with clonidine than oral gabapentine.

Abnormal Haemostasis and Blood Viscosity in Malignant Hypertension

1984 ◽  
Vol 52 (03) ◽  
pp. 253-255 ◽  
Author(s):  
C Isles ◽  
G D O Lowe ◽  
B M Rankin ◽  
C D Forbes ◽  
N Lucie ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Blood Viscosity ◽  
Renal Damage ◽  
Antithrombin Iii ◽  
Plasma Viscosity ◽  
Malignant Hypertension ◽  
Fibrin Deposition ◽  
Group 3 ◽  
Group 2 ◽  
Group 1

SummaryWe have previously shown abnormalities of haemostasis suggestive of intravascular coagulation in patients with malignant hypertension, a condition associated with retinopathy and renal fibrin deposition. To determine whether such abnormalities are specific to malignant hypertension, we have measured several haemostatic and haemorheological variables in 18 patients with malignant hypertension (Group 1), 18 matched healthy controls (Group 2), and 18 patients with non-malignant hypertension (Group 3) matched for renal pathology, blood pressure and serum creatinine with Group 1. Both Groups 1 and 3 had increased mean levels of fibrinogen, factor VIIIc, beta-thrombo- globulin, plasma viscosity and blood viscosity (corrected for haematocrit); and decreased mean levels of haematocrit, antithrombin III and platelet count. Mean levels of fast antiplasmin and alpha2-macroglobulin were elevated in Group 1 but not in Group 3. We conclude that most blood abnormalities are not specific to malignant hypertension; are also present in patients with non-malignant hypertension who have similar levels of blood pressure and renal damage; and might result from renal damage as well as promoting further renal damage by enhancing fibrin deposition. However increased levels of fibrinolytic inhibitors in malignant hypertension merit further investigation in relation to removal of renal fibrin.

Analysis of the quality of early diagnostics of cardiovascular diseases in students of educational institutions of Khabarovsk (according to the data of preventive examinations)

2020 ◽  
pp. 13-16
Keyword(s):  
Blood Pressure ◽  
Cardiovascular Diseases ◽  
Sinus Tachycardia ◽  
Blood Pressure Level ◽  
Educational Institutions ◽  
Conduction Disturbances ◽  
Group 3 ◽  
Group 2 ◽  
Group 1

To identify the prevalence of early pathology of cardiovascular diseases, a survey of 400 200 girls) in the age group 15 and 17 years old was conducted as a part of routine medical of the level of blood pressure (BP) was carried out, with the calculation of the average level pressure on the basis of three separate measurements estimated by percentile tables for a registration of a standard resting ECG in 12 leads. According to the results of the survey, into 3 groups: with an increase in blood pressure above 95 ‰ (group 1 – 16 people), which recorded in males (p<0,05); Group 2 (67 people) – adolescents with a normal blood pressure level and group 3 of adolescents with a decrease in blood pressure below 5 ‰ changes in the form of rhythm and conduction disturbances were noted in almost every a predominance of sinus tachycardia in the first group. In the third group of adolescents, form of ectopic rhythm and pacemaker migration were significantly more frequently only 78 % of adolescents were referred for consultation and in-depth examination by a pediatric cardiologist.

Epidural Clonidine or Bupivacaine as the Sole Analgesic Agent during and after Abdominal Surgery 

1999 ◽  
Vol 90 (5) ◽  
pp. 1354-1362 ◽  
Author(s):  
Marc De Kock ◽  
Philippe Gautier ◽  
Athanassia Pavlopoulou ◽  
Marc Jonniaux ◽  
Patricia Lavand'homme
Keyword(s):  
High Dose ◽  
General Anesthetics ◽  
Visual Analogue Pain ◽  
Pain Scores ◽  
Arterial Blood ◽  
Sedation Scores ◽  
Group 3 ◽  
Group 2 ◽  
High Doses ◽  
Group 1

Background The rationale of this study was to compare high-dose epidural clonidine with a more commonly used agent, such as bupivacaine. This was performed to give a more objective idea of the relative analgesic potency of epidural clonidine. Methods Sixty patients undergoing intestinal surgery during propofol anesthesia were studied. At induction, the patients received epidurally a dose of 10 micrograms/kg [corrected] clonidine in 7 ml saline followed by an infusion of 6 micrograms [corrected] x kg(-1) x h(-1) (7 ml/h) (group 1, n = 20), a dose of 7 ml bupivacaine, 0.5%, followed by 7 ml/h bupivacaine, 0.25% (group 2, n = 20), or a dose of 7 ml bupivacaine, 0.25%, followed by 7 ml/h bupivacaine, 0.125% (group 3, n = 20). Intraoperatively, increases in arterial blood pressure or heart rate not responding to propofol (0.5 mg/kg) were treated with intravenous alfentanil (0.05 mg/kg). Additional doses of propofol were given to maintain an adequate bispectral index. The epidural infusions were maintained for 12 h. In cases of subjective visual analogue pain scores up to 5 cm at rest or up to 8 cm during coughing, the patients were given access to a patient-controlled analgesia device. Results During anesthesia, patients in group 1 required less propofol than those in groups 2 and 3 (78 [36-142] mg vs. 229 [184-252] mg and 362 [295-458] mg; P &lt; 0.05) and less alfentanil than patients in group 3 (0 [0-0] mg vs. 11 [6-20] mg; P &lt; 0.05). Analgesia lasted 380 min (range, 180-645 min) in group 1 versus 30 min (range, 25-40 min) in group 2 and 22 min (range, 12.5-42 min) in group 3 (P &lt; 0.05). There was no suggestion of a hemodynamic difference among the three groups except for heart rates that were significantly reduced in patients in group 1. Sedation scores were significantly higher in this group during the first 2 h postoperatively. Conclusion Our results show that high doses of epidural clonidine potentiate general anesthetics and provide more efficient postoperative analgesia than the two bupivacaine dosage regimens investigated.

Electrical stimulation of cervical vagal afferents. II. Central relays for behavioral antinociception and arterial blood pressure decreases

1990 ◽  
Vol 64 (4) ◽  
pp. 1115-1124 ◽  
Author(s):  
A. Randich ◽  
K. Ren ◽  
G. F. Gebhart
Keyword(s):  
Blood Pressure ◽  
Arterial Blood Pressure ◽  
Nucleus Tractus Solitarius ◽  
Cardiovascular Response ◽  
Ibotenic Acid ◽  
Vagal Afferents ◽  
Ventrolateral Medulla ◽  
Tail Flick ◽  
Threshold Intensity ◽  
Arterial Blood

1. Supraspinal substrates mediating vagal afferent stimulation (VAS)-induced inhibition of the nociceptive tail-flick reflex were examined by the use of the soma-selective neurotoxin ibotenic acid and the nonselective local anesthetic lidocaine. Fifty rats were studied in the lightly anesthetized state maintained with pentobarbital sodium. 2. The threshold intensity of VAS required to inhibit the tail-flick reflex to a cut-off latency of 10 s was established in all rats. Ibotenic acid (5 or 10 micrograms, 0.5 microliter) or lidocaine (4%, 0.5 microliter) was then microinjected into various regions of the brain stem followed by reestablishment of the intensity of VAS required to produce inhibition of the tail-flick reflex. 3. Microinjections of ibotenic acid into the ipsilateral nucleus tractus solitarius (NTS), medial rostroventral medulla (principally the nucleus raphe magnus; NRM), or bilaterally into the dorsolateral pons (principally the locus coeruleus/subcoeruleus; LC/SC), significantly increased the threshold intensity of VAS required to inhibit the tail-flick reflex. Microinjections of ibotenic acid into either the rostral or caudal ventrolateral medulla (RVLM or CVLM, respectively) ipsilateral to the vagus nerve stimulated or ipsilateral LC/SC did not significantly affect the inhibition produced by VAS. Arterial blood pressure decreases produced by VAS were significantly attenuated or eliminated after microinjections of ibotenic acid into the NTS, RVLM, CVLM, or NRM. Lidocaine microinjected into the ipsilateral CVLM also significantly increased the intensity of VAS required to inhibit the tail-flick reflex. 4. These outcomes obtained with behavioral measures are consistent with the outcomes of the preceding study using electrophysiological measures in establishing that cells in the NTS, LC/SC, and NRM regions and fibers of passage in the CVLM are important in mediating the inhibitory effects of VAS. The present studies confirm previous reports of the importance of the RVLM and CVLM in VAS-produced depressor responses but also demonstrate that the NRM is critical for this cardiovascular response.

Sign in / Sign up

Export Citation Format

Share Document