Effects of hydralazine on blood pressure, pressor mechanisms, and cardiac hypertrophy in two-kidney, one-clip hypertensive rats

1986 ◽  
Vol 64 (12) ◽  
pp. 1528-1534 ◽  
Author(s):  
James Tsoporis ◽  
Frans H. H. Leenen
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Time Course ◽  
Antihypertensive Effect ◽  
Plasma Catecholamines ◽  
Left Ventricular ◽  
Prolonged Treatment ◽  
Internal Diameter ◽  
Hypertensive Rats ◽  
Blood Volumes

In 2-kidney, 1-clip hypertensive rats, the time course of changes in blood pressure (BP), heart rate, activity of the sympathetic nervous system and the renin–angiotensin system, plasma and blood volumes, left ventricular (LV) and right ventricular (RV) weight, and LV dimensions were evaluated during treatment with hydralazine 80 and 120 mg/L drinking water for 2 days or 1, 2, 3, 5, and 8 weeks. Hydralazine induced initially a clear antihypertensive effect (mean BP from 170–180 down to 135–145 mmHg (1 mmHg = 133.32 Pa)), subsequently tolerance developed. Heart rate, plasma catecholamines, and the blood pressure response to hexamethonium were not affected by treatment. Significant increases in plasma renin activity occurred during the initial 1–3 weeks of treatment. Plasma and blood volumes showed only small increases with prolonged treatment. RV weight and LV internal diameter showed significant increases at 3, 5, and 8 weeks of treatment, LV weight at 5 and 8 weeks. LV wall thickness did not change significantly. Thus, treatment with the arterial vasodilator hydralazine causes both RV hypertrophy and eccentric LV hypertrophy. Intravascular volume expansion, associated possibly with redistribution of blood volume to the central compartment, may play a major role in these cardiac effects. Increased renin release but not a generalized increase in sympathetic tone may play a role in the development of tolerance to the antihypertensive effect.

Ruta montana evokes antihypertensive activity through increase of prosta-glandins release in L-NAME-induced hypertensive rats

2020 ◽  
Vol 20 ◽  
Author(s):  
El-Ouady Fadwa ◽  
Mohamed Eddouks
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Aqueous Extract ◽  
Antihypertensive Effect ◽  
Antihypertensive Activity ◽  
Computer Assisted ◽  
Hypertensive Rats ◽  
Vasorelaxant Effect ◽  
Vasorelaxant Activity ◽  
Ruta Montana

Aims: The aim of the study was to investigate experimentally the antihypertensive effect of Ruta Montana. Background: Ruta montana L. is traditionally used in Moroccan herbal medicine to treat hypertension. This study aimed to evaluate experimentally the hypotensive and vasoactive properties of this plant. Objective: The objective of the study was to evaluate the effect of the aqueous extract of Ruta Montana on blood pressure parameters in LNAME-induced hypertensive rats and to determine the vasorelaxant activity of this aqueous extract. Methods: The antihypertensive effect of the aqueous extract obtained from Ruta montana aerial parts (RMAPAE) (200 mg/kg) was evaluated in normal and anesthetized hypertensive rats. Blood pressure parameters (systolic blood pressure (SBP), mean blood pressure (MBP) and diastolic blood pressure (DBP)) and heart rate were measured using a tail-cuff and a computer-assisted monitoring device. The acute and chronic effect of RMAPAE was recorded during 6 hours for the acute experiment and during 7 days for the sub-chronic test. In the other set, the vasorelaxant effect of RMAPAE on the contractile response was undertaken in isolated thoracic aorta. Results: The results indicated that RMAPAE extract significantly decreased SBP, MBP, DBP and heart rate in L-NAMEinduced hypertensive rats. Furthermore, RMAPAE was demonstrated to induce a dose dependent relaxation in the aorta precontracted with Epinephrine or KCl. More interestingly, this vasorelaxant activity of RMAPAE seems to be probably mediated through the prostaglandins pathway. Conclusion: The present study illustrates the beneficial action of Ruta montana on hypertension and supports then its use as an antihypertensive agent.

Dose-Response Curve and Time Course of the Antihypertensive Effect of SKF 92 657, a β-Receptor-Blocking and Vasodilating Compound

1980 ◽  
Vol 59 (s6) ◽  
pp. 461s-463s ◽  
Author(s):  
G. Leonetti ◽  
Laura Terzoli ◽  
Carla Sala ◽  
C. Bianchini ◽  
A. Zanchetti
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Response Curve ◽  
Time Course ◽  
Antihypertensive Effect ◽  
Blood Pressure Reduction ◽  
Dynamic Exercise ◽  
Β Receptor ◽  
Oral Doses ◽  
Uniform Reduction

1. The antihypertensive effect of the new drug, SKF 92 657, a hydrazinopyridazine derivative, possessing both β-adrenoreceptor-blocking and vasodilating properties, was investigated in essential hypertension. 2. Single oral doses of 1.0 or 2.0 mg/kg did not produce any consistent decrease in blood pressure; 4.0 mg/kg was the threshold dose for a mild but not significant blood pressure reduction, whereas 8.0 mg/kg caused a significant and marked blood pressure decrease without clinically relevant changes in heart rate. 3. Continued administration of the drug for 7 days induced a significant and uniform reduction in blood pressure without tachycardia. The increase in systolic blood pressure and in heart rate caused by dynamic exercise was left unaffected by the drug.

scholarly journals Physical Training as a Blood Pressure Reducer and a Remodeler of Cardiac Fibers in Spontaneously Hypertensive Rats (SHR)

2021 ◽  
pp. 22-30
Author(s):  
Mariana Molinar Mauad Cintra ◽  
Matheus Ribeiro Bizuti ◽  
Octávio Barbosa Neto ◽  
Marlene Antônia dos Reis ◽  
Lenaldo Branco Rocha ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Physical Training ◽  
Spontaneously Hypertensive Rats ◽  
Cardiac Fibrosis ◽  
Left Ventricular ◽  
Type Iii Collagen ◽  
Hypertensive Rats ◽  
Spontaneously Hypertensive ◽  
Type Iii

Background: Hypertension is the most prevalent of all cardiovascular diseases, reaching target organs such as the heart. Blood pressure control is critical for preventing organ damage induced by hypertension. Objective: To analyze blood pressure, heart rate, left ventricular thickness, the percentage of cardiac fibrosis and the percentage of type III collagen in Spontaneously Hypertensive Rats (SHR) submitted to swimming physical training. Methods: The experimental groups were composed of male Wistar Kyoto (WKY) rats (309-311g), which were divided into: 1) Normotensive Sedentary group (SN) (n = 6); 2) Trained Normotensive group (TN) (n = 6); 3) Sedentary Hypertensive group (SH) (n = 6); 4) Trained Hypertensive group (TH) (n = 6). After the end of the protocol, the animals were initially anesthetized to measure blood pressure. Results: Physical training was responsible for decreasing blood pressure (F = 16,968; p <0.001) and heart rate (F = 10.710; p = 0.004) in the trained groups (normotensive and hypertensive). Moreover, training was responsible for providing an increase in the thickness of the left ventricle (F = 7,254; p = 0.014) and a reduction in the percentage of cardiac fibrosis (F = 16,081; p <0.001). Furthermore, it was observed that the trained group had lower values of type III collagen (F = 13,166; p = 0.002). Conclusions: Physical swimming training triggered a decrease in blood pressure, heart rate, the percentage of fibrosis and the percentage of type III collagen. In addition, there was also a cardiac remodeling due to the increase in left ventricular hypertrophy.

Effects of sedation with dexmedetomidine and buprenorphine on echocardiographic variables, blood pressure and heart rate in healthy cats

2017 ◽  
Vol 20 (6) ◽  
pp. 554-562 ◽  
Author(s):  
Einar Johard ◽  
Anna Tidholm ◽  
Ingrid Ljungvall ◽  
Jens Häggström ◽  
Katja Höglund
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Interventricular Septum ◽  
Maximum Velocity ◽  
Left Ventricular ◽  
Aortic Diameter ◽  
Internal Diameter ◽  
Arterial Blood ◽  
Sedative Agents ◽  
Deceleration Time

Objectives Sedative agents are occasionally used to enable echocardiographic examination when screening cats for heart disease, such as hypertrophic cardiomyopathy (HCM). Owing to their haemodynamic effects, sedative agents may alter echocardiographic measurements. The aim of the study was to evaluate the effects of the sedative combination dexmedetomidine and buprenorphine on echocardiographic variables, blood pressure (BP) and heart rate (HR) in healthy cats. Methods Fifty healthy, client-owned cats were prospectively recruited and included after physical examination. Cats were sedated intramuscularly with dexmedetomidine and buprenorphine, according to body weight. Blood pressure and HR measurements, echocardiographic and Doppler examinations were performed prior to sedation and repeated once cats had achieved acceptable sedation. Results Left ventricular internal diameter at end-diastole and systole, right ventricular internal diameter at end-diastole, left atrium (LA), pulmonary artery (PA) deceleration time, and systolic, diastolic and mean arterial blood pressure increased after sedation ( P ⩽0.022). Aortic and PA maximum velocity, fractional shortening, PA acceleration/deceleration time and HR decreased after sedation ( P <0.0001). Interventricular septum at end-diastole and systole, left ventricular posterior wall at end-diastole and systole, aortic diameter (Ao), left atrial/aortic diameter (LA/Ao) and pulmonic acceleration time did not change. Conclusions and relevance Blood pressure increased and HR decreased post-sedation. While wall thickness and LA/Ao were not affected by sedation, indices of LA and left ventricular size increased. Further studies are needed using cats with HCM to assess the effect of this sedative combination on HCM screening results.

Sympathetic changes during development of cardiac hypertrophy in aortic-constricted rats

1988 ◽  
Vol 255 (3) ◽  
pp. H452-H457 ◽  
Author(s):  
F. M. Siri
Keyword(s):  
Heart Rate ◽  
Cardiac Hypertrophy ◽  
Nerve Stimulation ◽  
Sympathetic Nerve ◽  
Time Course ◽  
Plasma Catecholamines ◽  
Pressure Overload ◽  
Left Ventricular ◽  
Sympathetic Nerve Stimulation ◽  
Norepinephrine Turnover

Cardiac hypertrophy is frequently associated with sympathetic changes that include increased myocardial norepinephrine turnover, depleted myocardial norepinephrine stores, decreased myocardial responses to sympathetic nerve stimulation, and elevated plasma catecholamines. To better understand these events mechanistically, the time course of each was assessed in rat hearts subjected to aortic constriction-induced pressure overload. There was no evidence of increased left ventricular norepinephrine turnover in abdominal aortic-constricted rats, when compared with sham-constricted animals, during the first 3 days postoperatively. Moreover, their turnover rate constants tended to be lower during this period, then increased significantly by day 7. Plasma catecholamines were increased and left ventricular norepinephrine stores were decreased only on day 7. Heart rate responses to maximal sympathetic nerve stimulation were significantly reduced on the third postoperative day. Thus the decrease in norepinephrine stores coincided with changes in left ventricular norepinephrine turnover and plasma catecholamines, whereas the reduction in heart rate responses did not. This pattern suggests an initial reflex decrease in myocardial sympathetic tone, followed by baroreceptor resetting, with an eventual increase in general sympathetic outflow. The period of increasing catecholamine stimulation occurred after a relative left ventricular hypertrophy had developed but before a significant increase in absolute left ventricular mass. Thus catecholamines may still importantly contribute to the hypertrophy seen in this model.

Baroreflex Sensitivity Changes during the Development of Goldblatt Two-Kidney One-Clip Hypertension in Rats

1980 ◽  
Vol 59 (5) ◽  
pp. 347-352 ◽  
Author(s):  
J. V. Jones ◽  
J. S. Floras
Keyword(s):  
Renovascular Hypertension ◽  
Time Course ◽  
Baroreflex Sensitivity ◽  
Left Ventricular ◽  
Control Group ◽  
Internal Diameter ◽  
Hypertensive Rats ◽  
Male Wistar Rats ◽  
Baroreceptor Reflex Sensitivity ◽  
Sensitivity Changes

1. The time course of changes in baroreceptor reflex sensitivity during the development of renovascular hypertension was studied in male Wistar rats in which the left renal arteries were constricted by silver wire clips of 0.18 mm internal diameter. 2. Groups of animals were studied at 3, 7, 14 and 25 days after induction of renovascular hypertension. Rats of comparable ages were included as controls. There was a significant decrease in mean baroreflex sensitivity from 0.950 ± 0.157 ms/mmHg (n = 8) in the normal control group to 0.537 ± 0.105 ms/mmHg (n = 8) in the 3 day hypertensive group (P < 0.05). Baroreflex sensitivity in the 3 day hypertensive rats was independent of the level of arterial pressure achieved in individual animals. 3. These changes in baroreflex sensitivity at 3 days precede the development of left ventricular hypertrophy and, as previously shown in this model, also precede structural vascular adaptation and resetting of the carotid sinus baroreceptor threshold. 4. A further loss of baroreflex sensitivity, which may be structurally based, occurred later. Baroreflex sensitivity in the 14 day hypertensive rats fell to 0.182 ± 0.039 ms/mmHg (n = 8) compared with the 3 day hypertensive rats (P < 0.01).

scholarly journals Antihypertensive Effect ofSyzygium cuminiin Spontaneously Hypertensive Rats

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Rachel Melo Ribeiro ◽  
Vicente Férrer Pinheiro Neto ◽  
Kllysmann Santos Ribeiro ◽  
Denilson Amorim Vieira ◽  
Iracelle Carvalho Abreu ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Spontaneously Hypertensive Rats ◽  
Wistar Rats ◽  
Vascular Reactivity ◽  
Antihypertensive Effect ◽  
Maximum Effect ◽  
Syzygium Cumini ◽  
Hypertensive Rats ◽  
Spontaneously Hypertensive

This study evaluated thein vivopotential antihypertensive effect of hydroalcoholic extract ofSyzygium cuminileaves (HESC) in normotensive Wistar rats and in spontaneously hypertensive rats (SHR), as well as itsin vitroeffect on the vascular reactivity of resistance arteries. The hypotensive effect caused by intravenous infusion of HESC (0.01–4.0 mg/kg) in anesthetized Wistar rats was dose-dependent and was partially inhibited by pretreatment with atropine sulfate. SHR received HESC (0.5 g/kg/day), orally, for 8 weeks and mean arterial pressure, heart rate, and vascular reactivity were evaluated. Daily oral administration of HESC resulted in a time-dependent blood pressure reduction in SHR, with a maximum reduction of 62%. In the endothelium-deprived superior mesenteric arteries rings the treatment with HESC reduced by 40% the maximum effect (Emax⁡) of contraction induced by NE. The contractile response to calcium and NE of endothelium-deprived mesenteric rings isolated from untreated SHR was reduced in a concentration-dependent manner by HESC (0.1, 0.25, and 0.5 mg/mL). This study demonstrated thatSyzygium cuminireduces the blood pressure and heart rate of SHR and that this antihypertensive effect is probably due to the inhibition of arterial tone and extracellular calcium influx.

HEART COMPLICATIONS IN HYPERTHYROIDISM

2011 ◽  
pp. 7-17
Author(s):  
Hai Thuy Nguyen ◽  
Anh Vu Nguyen
Keyword(s):  
Atrial Fibrillation ◽  
Blood Pressure ◽  
Heart Rate ◽  
Heart Diseases ◽  
Systolic Dysfunction ◽  
Oxygen Demand ◽  
Left Ventricular ◽  
Cardiac Contraction ◽  
Cardiac Complications ◽  
Cardiac Symptoms

Thyroid hormone increases the force of the contraction and the amount of the heart muscle oxygen demand. It also increases the heart rate. Due to these reasons, the work of the heart is greatly increased in hyperthyroidism. Hyperthyroidism increases the amount of nitric oxide in the intima, lead them to be dilated and become less stiff. Cardiac symptoms can be seen in anybody with hyperthyroidism, but can be particularly dangerous in whom have underlying heart diseases. Common symptoms include: tachycardia and palpitations. Occult hyperthyroidism is a common cause of an increased heart rate at rest and with mild exertion. Hyperthyroidism can also produce a host of other arrhythmias such as PVCs, ventricular tachycardia and especially atrial fibrillation. Left ventricular diastolic dysfunction and systolic dysfunction, Mitral regurgitation and mitral valve prolapsed are heart complications of hyperthyroism could be detected by echocardiography. The forceful cardiac contraction increases the systolic blood pressure despite the increased relaxation in the blood vessels reduces the diastolic blood pressure. Atrial fibrillation, atrial enlargement and congestive heart failure are important cardiac complications of hyperthyroidism. An increased risks of stroke is common in patients with atrial fibrillation. Graves disease is linked to autoimmune complications, such as cardiac valve involvement, pulmonary arterial hypertension and specific cardiomyopathy. Worsening angina: Patients with coronary artery disease often experience a marked worsening in symptoms with hyperthyroidism. These can include an increase in chest pain (angina) or even a heart attack.

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.

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