Is Substance P the Transmitter at the First Synapse of the Baroreceptor Reflex in Rats and Cats?

1980 ◽  
Vol 59 (s6) ◽  
pp. 295s-297s ◽  
Author(s):  
G. Haeusler ◽  
R. Osterwalder
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Substance P ◽  
Cardiovascular Effects ◽  
Baroreceptor Reflex ◽  
Solitary Tract ◽  
Anaesthetized Rats ◽  
Contrast Exposure ◽  
Brain Ventricle ◽  
Dose Dependent

1. Substance P, injected into a lateral brain ventricle of urethane-anaesthetized rats, caused dose-dependent increases in blood pressure and heart rate. 2. By contrast, exposure of the obex region of the medulla oblongata to pieces of filter paper soaked in substance P-containing solution resulted in falls of blood pressure and heart rate in both rats and cats. 3. A more precise application of substance P to the first synapse of the baroreceptor reflex by micro-injection into defined areas of the nucleus of the solitary tract also led to an activation of the baroreceptor reflex. 4. Capsaicin, which is known to release substance P from primary afferents, mimicked the sympatho-inhibitory and cardiovascular effects of substance P when applied locally to the nucleus of the solitary tract. 5. The results are compatible with a transmitter or neuromodulatory role for substance P at the first synapse of the baroreceptor reflex.

scholarly journals Cardiovascular effects of reflexology in healthy individuals: evidence for a specific increase in blood pressure

2012 ◽  
Vol 2 (1) ◽  
pp. 4 ◽  
Author(s):  
Elisabeth Ruiz Padial ◽  
Nieves Torres López ◽  
Javier Luna Bujaldón ◽  
Isabel Espadas Villanueva ◽  
Gustavo Reyes del Paso
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Heart Rate Variability ◽  
Waiting Time ◽  
Healing Process ◽  
Cardiovascular Effects ◽  
Baroreceptor Reflex ◽  
Control Group ◽  
Time Control ◽  
Baroreceptor Reflex Sensitivity

The present study evaluates the cardiovascular effects of reflexology in a healthy sample. Forty-one participants were randomly assigned to one of three experimental groups: reflexology (n=15), non-professional foot massage (n=14), and a waiting time control group (n=12). Dependent variables were systolic, diastolic and mean blood pressure, inter-beat interval, heart rate variability and baroreceptor reflex sensitivity measured pre- and post- interventions. The study was performed during three 40-min sessions separated by weekly intervals. Results show that the three manipulations produce similar increases in inter-beat interval, heart rate variability and baroreceptor reflex sensitivity. Reflexology specifically produces an increase in blood pressure, which increases gradually over the three sessions. The parallel increase in heart rate variability and baroreceptor reflex sensitivity together with the increase in blood pressure suggest that reflexology is associated with a co-activation of both sympathetic and parasympathetic branches of the Autonomic Nervous System. These changes could be helpful in optimizing homeostatic activity, promoting the healing process and increasing the human organism’s capacity to respond adaptively to internal and external challenges. Finally, the observed physiological changes in the waiting-time control group shows the relevance of habituation processes and suggests the need for addition of waiting-time control groups in future studies.

Blocking properties of terguride at the 5-HT2 receptor subtypes mediating cardiovascular responses in the rat

2020 ◽  
Vol 98 (8) ◽  
pp. 511-521
Author(s):  
Oscar Alcántara-Vázquez ◽  
Ma. Trinidad Villamil-Hernández ◽  
Araceli Sánchez-López ◽  
Heinz H. Pertz ◽  
Carlos M. Villalón ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Diastolic Blood Pressure ◽  
Receptor Agonist ◽  
Cardiovascular Responses ◽  
Receptor Subtypes ◽  
Pithed Rats ◽  
Anaesthetized Rats ◽  
Dose Dependent

In vitro studies have suggested that terguride blocks the contractile and relaxant responses produced by 5-hydroxytryptamine (5-HT) via 5-HT2A/2B receptors. This study has now investigated terguride’s blocking properties on central/peripheral 5-HT2 receptors in anaesthetized or pithed rats. Male Wistar anaesthetized/pithed rats were cannulated for recording blood pressure and heart rate and for i.v. administration of several compounds. In both groups of rats, i.v. bolus injections of 5-HT or (±)-DOI (a 5-HT2 receptor agonist; 1–1000 μg/kg) produced dose-dependent increases in diastolic blood pressure and heart rate. These responses were dose-dependently antagonized by terguride (10–3000 μg/kg). In anaesthetized rats, i.v. bolus injections of BW723C86 (a 5-HT2B receptor agonist; 1–1000 μg/kg) produced dose-dependent increases in diastolic blood pressure and not dose-dependent increases in heart rate, while in pithed rats, these responses were attenuated. The vasopressor responses elicited by BW723C86 in anaesthetized rats were dose-dependently blocked by terguride (10–300 μg/kg), whereas its the tachycardic responses were dose-independently blocked. These results, taken together, suggest that terguride behaved as an antagonist at the 5-HT2 receptors located in the central nervous system and (or) the systemic vasculature. This is the first evidence demonstrating that terguride can block central/peripheral 5-HT2 receptors mediating cardiovascular responses in anaesthetized or pithed rats.

Cardiovascular actions of trout urotensin II in the conscious trout, Oncorhynchus mykiss

1996 ◽  
Vol 271 (5) ◽  
pp. R1335-R1343 ◽  
Author(s):  
J. C. Le Mevel ◽  
K. R. Olson ◽  
D. Conklin ◽  
D. Waugh ◽  
D. D. Smith ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Arterial Blood Pressure ◽  
Cardiovascular Effects ◽  
Pressor Effect ◽  
Urotensin Ii ◽  
Cardinal Vein ◽  
Vascular Rings ◽  
Arterial Blood ◽  
Dose Dependent

The central and peripheral cardiovascular effects of synthetic trout urotensin II (UII) were investigated in the conscious rainbow trout. Intracerebroventricular injection of 50 pmol UII produced a slight (3%) but significant (P < 0.05) increase in heart rate but had no effect on mean arterial blood pressure. Injection of 500 pmol UII icv produced a significant (P < 0.05) rise (8%) in blood pressure with no change in heart rate. In contrast to the weak pressor effect of centrally administered UII, intra-arterial injection of UII produced a dose-dependent increase in arterial blood pressure and decrease in heart rate with significant (P < 0.05) effects on both parameters observed at a dose of 25 pmol. Higher doses of the peptide produced a sustained decrease in cardiac output that accompanied the bradycardia and rise in arterial blood pressure. The UII-induced bradycardia, but not the increase in pressure, was abolished by pretreatment with phentolamine. Trout UII produced a sustained and dose-dependent contraction of isolated vascular rings prepared from trout efferent branchial [-log 50% of the concentration producing maximal contraction (pD2) = 8.30] and celiacomesenteric (pD2 = 8.22) arteries but was without effects on vascular rings from the anterior cardinal vein. The data indicate that the pressor effect of UII in trout is mediated predominantly, if not exclusively, by an increase in systemic vascular resistance. The UII-induced hypertensive response does not seem to involve release of catecholamines, but the bradycardia may arise from adrenergic-mediated activation of cardioinhibitory baroreflexes.

The Role of the Baroreceptor Reflex in the Cardiovascular Effects of Propranolol in the Conscious Spontaneously Hypertensive Rat

1979 ◽  
Vol 56 (2) ◽  
pp. 163-167 ◽  
Author(s):  
H. A. J. Struyker-Boudier ◽  
J. F. Smits ◽  
H. Van Essen
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Cardiac Output ◽  
Spontaneously Hypertensive Rat ◽  
Cardiovascular Effects ◽  
Hypotensive Effect ◽  
Baroreceptor Reflex ◽  
Acute Effects ◽  
Spontaneously Hypertensive

1. The role of baroreceptors in the cardiovascular mechanism of action of dl-propranolol has been studied by comparing the acute effects of subcutaneous injection of 1 and 5 mg/kg (3·3 × 10−6 and 16·5 × 10−6 mol/kg) of this drug in conscious baroreceptor-denervated spontaneously hypertensive (SH) rats with those in sham-operated control SH rats. 2. At 5 mg/kg (16·5 × 10−6 mol/kg) propranolol caused a small, but significant, increase in blood pressure in sham-operated SH rats, whereas both after 1 and 5 mg/kg (3·3 × 10−6 and 16·5 × 10−6 mol/kg) immediate hypotension was observed in baroreceptor-denervated animals. 3. Heart rate dropped rapidly after injection of 1 or 5 mg/kg (3·3 × 10−6 and 16·5 × 10−6 mol/kg) propranolol both in the baroreceptor-denervated and sham-operated SH rats. Bradycardia was significantly larger in the baroreceptor-denervated animals after an injection of 5 mg/kg (16·5 × 10−6 mol/kg). 4. It is concluded that the lack of an early hypotensive effect of propranolol in intact animals is caused by an increased baroreceptor reflex activity as a consequence of the fall in cardiac output.

Cardiovascular effects of peptide kinin B2 receptor antagonists in rats

2002 ◽  
Vol 80 (4) ◽  
pp. 310-322 ◽  
Author(s):  
F Carini ◽  
M Guelfi ◽  
A Lecci ◽  
M Tramontana ◽  
S Meini ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Time Course ◽  
Cardiovascular Effects ◽  
Receptor Antagonists ◽  
Indwelling Catheter ◽  
Induced Hypotension ◽  
Conscious Rats ◽  
Anaesthetized Rats ◽  
The Right

Bradykinin (BK) is a vasoactive peptide reputed to play an important role in cardiovascular homeostasis. In this study, we describe the cardiovascular changes (mean blood pressure (BP) and heart rate (HR)) induced by the i.v. administration (left jugular vein) of two selective kinin B2 receptor antagonist, namely icatibant (0.1–1 µmol/kg as a bolus) and MEN11270 (0.1–1 µmol/kg as a bolus or 1 µmol/kg infused in 15 or 60 min), in urethane-anaesthetized or conscious rats with an indwelling catheter implanted in the right carotid artery for BP measurements. In conscious rats, icatibant at 0.1 or 0.3 µmol/kg did not change BP but at 0.1 µmol/kg increased HR at 30 min from administration. MEN11270 at 0.1 or 0.3 µmol/kg induced a dose-related increase in BP and a concomitant bradycardia (significant at 0.3 µmol/kg) lasting for 5 or 30 min, respectively. Icatibant at 1 µmol/kg induced a slight (P < 0.05) increase in BP that resolved in 5 min and a biphasic tachycardia (peaks at 30 and 90 min from administration). MEN11270 at 1 µmol/kg induced a triphasic change in HR (tachycardia in the first 5 min, bradycardia at 30 min, and tachycardia at 90 and 120 min) and a biphasic change in BP (hypotension at 15 min and hypertension at 30 min). The i.v. infusion of MEN11270 (1 µmol/kg in 15 or 60 min) produced hypertension, whereas HR was increased only following the 15-min infusion. In urethane-anaesthetized rats, both icatibant and MEN11270 (0.1 µmol/kg as a bolus) increased BP and the onset for this effect was correlated with the time course of the antagonism of BK-induced hypotension, where the effect of MEN11270 was more rapid than that of icatibant. These results indicate that kinin B2 receptor antagonists can induce acute cardiovascular effects, and the reason for the different haemodynamic profile between icatibant and MEN11270 could be putatively attributed to kinetic characteristics.Key words: icatibant, MEN11270, bradykinin, blood pressure, heart rate.

Serotonergic Mechanisms in the Nucleus Tractus Solitarius May Regulate Blood Pressure and Behaviour in the Rat

1982 ◽  
Vol 63 (s8) ◽  
pp. 323s-326s ◽  
Author(s):  
R. Laguzzi ◽  
W. T. Talman ◽  
D. J. Reis
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Arterial Pressure ◽  
Nucleus Tractus Solitarius ◽  
Baroreceptor Reflex ◽  
Behavioural Responses ◽  
Neuronal Populations ◽  
Eeg Changes ◽  
Electroencephalogram Eeg ◽  
Dose Dependent

1. Highly localized microinjections of serotonin into the nucleus tractus solitarius in rats produced dose-dependent hypotension and bradycardia and electroencephalogram (EEG) changes consistent with an alerting response. 2. Microinjection of the serotinin antagonist metergoline blocked the cardiovascular and EEG effects of serotonin but did not affect the same responses elicited by the microinjection of l-glutamate. 3. Microinjections of l-glutamate produced similar effects; acetylcholine, which lowered arterial pressure and heart rate, did not affect the EEG. 4. Bilateral injections of metergoline into the nucleus tractus solitarius occasionally produced a rise in arterial pressure but did not affect the baroreceptor reflex. 5. Serotonin may integrate cardiovascular and behavioural responses mediated by the nucleus tractus solitarius. 6. Neuronal populations within the nucleus tractus solitarius may be neurochemically and functionally differentiated.

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.

Cardiovascular Effects of Aerobic Exercise With Self-Selected or Predetermined Intensity in Adolescents With Obesity

2021 ◽  
pp. 1-7
Author(s):  
Tércio A.R. Barros ◽  
Wagner L. do Prado ◽  
Thiago R.S. Tenório ◽  
Raphael M. Ritti-Dias ◽  
Antônio H. Germano-Soares ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Body Mass Index ◽  
Heart Rate ◽  
Pulse Pressure ◽  
Exercise Intensity ◽  
Pulse Wave ◽  
Augmentation Index ◽  
Cardiovascular Effects ◽  
Heart Rate Reserve ◽  
Central Pulse Pressure

This study compared the effects of self-selected exercise intensity (SEI) versus predetermined exercise intensity (PEI) on blood pressure (BP) and arterial stiffness in adolescents with obesity. A total of 37 adolescents, 14.7 (1.6) years old, body mass index ≥95th percentile were randomly allocated into SEI (n = 18; 12 boys) or PEI (n = 19; 13 boys). Both groups exercised for 35 minutes on a treadmill, 3 times per week, for 12 weeks. The SEI could set the speed at the beginning of the sessions and make changes every 5 minutes. The PEI adolescents were trained at an intensity set at 60% to 70% of heart rate reserve. Brachial and central BP, pulse pressure, augmentation index, and carotid–femoral pulse wave were determined at baseline and after 12 weeks. Both groups reduced brachial systolic BP (SEI, Δ = −9 mm Hg; PEI, Δ = −4 mm Hg; P < .01), central systolic BP (SEI, Δ = −4 mm Hg; PEI, Δ = −4 mm Hg; P = .01), and central pulse pressure (SEI, Δ = −4 mm Hg; PEI, Δ = −3 mm Hg; P = .02) without differences between groups. No changes in the augmentation index and carotid–femoral pulse wave were observed in either group. The SEI induced similar changes in various cardiovascular outcomes compared with PEI in adolescents with obesity.

scholarly journals Cardiovascular effects of lumbar epidural anaesthesia in isoflurane-anaesthetised pigs during surgical removal of the liver

2009 ◽  
Vol 80 (1) ◽  
Author(s):  
G.F. Stegmann
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Abdominal Surgery ◽  
Epidural Anaesthesia ◽  
Cardiovascular Effects ◽  
Surgical Removal ◽  
Arterial Blood ◽  
Combined Administration ◽  
Lumbar Epidural Anaesthesia ◽  
Surgical Preparation

In humans the combined administration of epidural anaesthesia and inhalation anaesthesia may result in cardiovascular instability associated with decreases in heart rate and blood pressure. Anaesthesia was induced with a combination of midazolam / ketamine in 18 female pigs with a mean body weight of 24.9±5.9 kg scheduled for surgical removal of the liver. After tracheal intubation, anaesthesia was maintained on a circle rebreathing circuit with isoflurane. Epidural anaesthesia was administered with ropivacaine (AL-group, n=8) at 0.2 mℓ / kg of a 7.5 mg / mℓ solution to the anaesthetised animals. The A-group (n = 10) received isoflurane anaesthesia only. The vaporiser was set at 2.5 % for the A-group and 1.5 % for the AL-group. Heart rate, invasive systolic, diastolic, and mean arterial blood pressure were monitored. Comparisons were made between treatments and within treatments comparing variables during surgical preparation and abdominal surgery. Differences between treatments were not statistically significant (P > 0.05) during surgical preparation or during abdominal surgery. For within treatment groups, the differences between surgical preparation and abdominal surgery were statistically significant (P < 0.05) for heart rate in the A-group, but not statistically significant (P > 0.05) for the other variables. It is concluded that abdominal surgery may be associated with statistically significant changes in heart rate in isoflurane-anaesthetised pigs and that the combined administration of epidural ropivacaine may prevent statistically significant changes in HR during abdominal surgery.

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