Antiarrhythmic effects of selective beta 1- and beta 2- and nonselective beta-adrenoceptor blockade in normokalaemic and dietary-induced hypokalaemic rats.

Journal of Cardiovascular Pharmacology
E WinslowR Mason

Abstract

Hypokalaemia (HK) is a risk factor for development of clinical arrhythmias, and epinephrine (Epi), released after myocardial infarction, may itself induce HK. The effects of selective beta 1- and beta 2-blockade with metoprolol (M) and ICI 118551 (I), respectively, and non-selective blockade with propranolol (P) against early ischaemia-induced arrhythmias were therefore compared in normokalaemic (NK) and dietary-induced HK rats. Plasma Epi, norepinephrine (NE), and K+ levels were also measured. All three blockers [5-10 mg/kg intravenously (i.v.)] were antifibrillatory in NK rats, whereas I and P (2-10 mg/kg) additionally reduced the number of ventricular premature beats. Coronary artery ligation increased plasma Epi levels in both NK an HK rats, but plasma NE increased further in HK rats. HK was also associated with an increased arrhythmia severity and negation of the antifibrillatory action of M. In contrast, I and P retained antiarrhythmic and antifibrillatory effects in HK animals and increased survival. Both I and P increased plasma K+ levels in both NK and HK animals whereas M did not. We concluded that beta 2-receptor-mediated HK after coronary occlusion may play a substantial role in arrhythmogenesis. Protection afforded...Continue Reading

Related Concepts

Related Feeds

Arrhythmia

Arrhythmias are abnormalities in heart rhythms, which can be either too fast or too slow. They can result from abnormalities of the initiation of an impulse or impulse conduction or a combination of both. Here is the latest research on arrhythmias.

Anti-Arrhythmic Drug Therapies

Anti-arrhythmic drugs are used to prevent abnormal heart rhythms. These medications are used in conditions including, ventricular tachycardia, ventricular fibrillation and atrial fibrillation. Discover the latest research on anti-arrhythmic drug therapies here.

Atrial Fibrillation

Atrial fibrillation is a common arrhythmia that is associated with substantial morbidity and mortality, particularly due to stroke and thromboembolism. Here is the latest research.

Adrenergic Receptors: Trafficking

Adrenergic receptor trafficking is an active physiological process where adrenergic receptors are relocated from one region of the cell to another or from one type of cell to another. Discover the latest research on adrenergic receptor trafficking here.

Antiarrhythmic Agents: Mechanisms of Action

Understanding the mechanism of action of antiarrhythmic agents is essential in developing new medications as treatment of cardiac arrhythmias is currently limited by the reduced availability of safe and effective drugs. Discover the latest research on Antiarrhythmic Agents: Mechanism of Action here.