Related Experiment Video

Updated: Oct 23, 2026

Implantation of Combined Telemetric ECG and Blood Pressure Transmitters to Determine Spontaneous Baroreflex Sensitivity in Conscious Mice
09:56

Implantation of Combined Telemetric ECG and Blood Pressure Transmitters to Determine Spontaneous Baroreflex Sensitivity in Conscious Mice

Published on: February 14, 2021

Effect of beta blockade with and without sympathomimetic activity (ISA) on sympathovagal balance and baroreflex

C Haberthür1, H Schächinger, W Langewitz

  • 1Department of Internal Medicine, University Hospital Basle, Switzerland.

Clinical Physiology (Oxford, England)
|April 14, 1999
PubMed

Insights

Beta blockers without intrinsic sympathomimetic activity (ISA) increase heart rate variability (HRV), while those with ISA do not improve autonomic balance. Pindolol with ISA exaggerates sympathetic responses to passive tilt, unlike propranolol.

Area of Science:

  • Cardiology
  • Autonomic Nervous System Physiology

Background:

  • Beta blockers are known to increase heart rate variability (HRV) and improve survival in coronary artery disease (CAD).
  • The efficacy of beta blockers with intrinsic sympathomimetic activity (ISA) in CAD remains debated, and their impact on HRV is not well-established.

Purpose of the Study:

  • To investigate the effects of propranolol (without ISA) and pindolol (with potent ISA) on HRV, blood pressure variability (BPV), and baroreflex sensitivity (BRS) in healthy subjects.
  • To compare the autonomic effects of beta blockers with and without ISA.

Main Methods:

  • Thirty healthy subjects (aged 21-39 years) participated in the study.
  • Measurements of HRV, BPV, and BRS were taken under controlled frequency breathing in supine and tilt positions.
  • Subjects received propranolol (160 mg q.d.), pindolol (15 mg q.d.), or placebo (q.d.).

Main Results:

  • Propranolol increased high-frequency HRV, decreased low-frequency BPV (Mayer waves), and enhanced BRS in the supine position.
  • Propranolol decreased low-frequency HRV and Mayer waves after passive tilt.
  • Pindolol increased the low-frequency HRV response to passive tilt, unlike propranolol and placebo.

Conclusions:

  • Beta-adrenergic blockade with potent ISA (pindolol) does not increase HRV and offers no benefit to autonomic balance.
  • Beta blockers with ISA may even amplify sympathetic responses during physiological stress like passive tilt.
  • These findings suggest that beta blockers without ISA may be more beneficial for autonomic regulation.

More Related Videos

Quantifying Acute Changes in Renal Sympathetic Nerve Activity in Response to Central Nervous System Manipulations in Anesthetized Rats06:30

Quantifying Acute Changes in Renal Sympathetic Nerve Activity in Response to Central Nervous System Manipulations in Anesthetized Rats

Published on: September 11, 2018

Understanding the Effects of Non-Invasive Transauricular Vagus Nerve Stimulation on EEG and HRV04:59

Understanding the Effects of Non-Invasive Transauricular Vagus Nerve Stimulation on EEG and HRV

Published on: January 19, 2024

Related Concept Videos

Adrenergic Antagonists: Pharmacological Actions of β-Receptor Blockers01:27

Adrenergic Antagonists: Pharmacological Actions of β-Receptor Blockers

β-receptor blockers significantly impact the cardiovascular system by counteracting catecholamine-induced sympathetic responses. These medications decrease heart rate, contractility, and cardiac output, potentially leading to cardiac depression, life-threatening bradycardia, and death. Therapeutically, β-blockers function as mild antihypertensives and are utilized in treating angina pectoris and cardiac arrhythmias. However, nonselective β-blockers inhibit β2-receptors in bronchial smooth...
Antihypertensive Drugs: Types of β-Blockers01:28

Antihypertensive Drugs: Types of β-Blockers

β receptors are classified into three subclasses: β1, β2, and β3. β1 receptors are primarily located in the heart and kidneys. When they get activated, they increase heart rate, contractility, and renin release. This process enhances blood pressure and aids in stress management. In contrast, β2 receptors are situated mainly in the lungs, blood vessels, and skeletal muscles. Upon activation, they trigger smooth muscle relaxation, causing bronchodilation and vasodilation. This widens airways and...
Heart Failure Drugs: β-Blockers01:22

Heart Failure Drugs: β-Blockers

β-adrenergic antagonists, commonly known as β-blockers, block the effects of sympathetic neurotransmitters such as noradrenaline (NA) and adrenaline (ADR). They have several beneficial effects in heart failure treatment. They reduce heart rate, the force of contraction, and cardiac muscle relaxation. They also slow the atrial-ventricular conduction rate and raise the threshold for arrhythmias. The concentration of β-blockers determines their effects on bronchodilation, vasodilation, and...
Antihypertensive Drugs: Action of β1 Blockers01:17

Antihypertensive Drugs: Action of β1 Blockers

β1-receptors are primarily located in the heart and kidneys. In cardiac myocytes, these receptors interact with neurotransmitters released by the sympathetic nervous system during heightened activity or danger. As a result, β1-receptors get activated, initiating a series of biochemical processes. Excessive activation of beta receptors due to chronic stress can abnormally increase heart rate and contractility, resulting in high blood pressure or hypertension. To counteract this, β1-blockers...
Adrenergic Antagonists: ɑ and β-Receptor Blockers01:31

Adrenergic Antagonists: ɑ and β-Receptor Blockers

Third-generation β-blockers, such as labetalol and carvedilol, represent a significant advancement in managing cardiovascular conditions. Unlike conventional β-blockers, which can induce peripheral vasoconstriction, third-generation drugs block α1 adrenoceptors. This promotes vasodilation through several mechanisms, such as increased nitric oxide production, inhibition of calcium ion entry, opening of potassium ion channels, and antioxidant action. Labetalol, for instance, is clinically...
Regulation of the Cardiovascular System01:27

Regulation of the Cardiovascular System

The regulation of the cardiovascular system allows the body to adapt to various demands and maintain homeostasis.
The regulation of the cardiovascular system involves the autonomic nervous system (ANS), baroreceptors, and chemoreceptors, ensuring that heart rate and blood pressure are appropriately modulated in response to varying physiological demands.
The ANS comprises two main divisions: the sympathetic and parasympathetic nervous systems. The sympathetic nervous system enhances...