Beta blockers are drugs that alter adrenergic response to catecholamines such as epinepherine and norepinephrine, by inhibiting beta adrenergic receptors; these receptors are found in various concentrations and are prevalent in the heart and arteries. The use of beta blockers may have adverse effects on triglycerides concentrations in the blood.
Types of Beta Receptors
The two major types of beta receptors are: beta-1 and beta-2 receptors. Both receptors are stimulated naturally by epinephrine and norepinpherine. Beta-1 receptors are found in the sinoatrial and atrioventricular nodes of the heart. Beta-2 receptors are found on smooth muscles of the arteries and on beta cells of the pancreas. Stimulation of beta-1 receptors increases heart rate. Stimulation of beta-2 receptors causes vasodilation of arteries by smooth muscle relaxation; it also relaxes smooth muscles of the bronchi, uterus and iris.
The Adrenergic Drive
The sympathetic nervous system is part of the autonomic nervous system, which acts automatically in response to stimulus; it modulates heart function by increasing heart rate during elevated stress, exercise, anxiety and any conditions that increase oxygen demand. The sympathetic nervous system increases the heart rate by stimulating beta-1 adrenergic receptors in the pacemaker cells of the heart.
Elevated Triglyceride
The elevation of triglyceride as a consequence of beta blocker use raises concerns for increased risk for coronary heart disease. According to an article published in the May 1978 "British Medical Journal," there is no strong evidence suggesting that elevated triglycerides resulting from beta blocker use increases risks for coronary heart disease.
Benefits of Beta Blockers
Beta blockers reduce mortality associated with congestive heart failure and heart attacks; in these conditions, there is increased oxygen demand and decreased perfusion of blood to heart muscle as it compensates by increasing heart rate. Beta blockers slow the heart rate, allowing more time for blood to perfuse the heart muscle; they also reduce the levels of catecholamines, which decreases blood pressure and workload on the heart.
