PMID: 7528997Dec 1, 1994Paper

Mechanism of the negative inotropic effect of adenosine in guinea pig atrial myocytes

The American Journal of Physiology
D Wang, L Belardinelli

Abstract

The ionic basis of the negative inotropic effect of adenosine on guinea pig atrial myocytes was studied. Membrane potentials and currents were measured using a whole cell patch-clamp technique. The contractility was assessed by video quantitation of cell twitch amplitude. Adenosine shortened action potential duration [measured at 90% repolarization (APD90)] and decreased twitch amplitude in a concentration-dependent manner. The maximal effects of adenosine (100 microM) were to reduce APD90 from 102 +/- 14 to 34 +/- 8 ms (n = 11) and twitch amplitude from 4.3 +/- 0.9 to 1.5 +/- 0.4 microns (n = 8). The concentration of adenosine that caused one-half of the maximal reductions of twitch amplitude and of APD90 was 0.6 microM. Reductions in APD90 and in twitch amplitude were parallel and highly correlated (r = 0.98). Decreases in twitch amplitude by adenosine could be mimicked by application of voltage-clamp pulses with durations similar to the durations of action potentials in the presence of adenosine. Clamp pulse could reverse adenosine-induced but not cadmium chloride-induced decreases in twitch amplitude. Adenosine activated the inwardly rectifying K+ current (IK,Ado), but did not significantly decrease the L-type Ca2+ current ...Continue Reading

Related Concepts

Related Feeds

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.

Atrial Filbrillation

Atrial fibrillation refers to the abnormal heart rhythm characterized by rapid and irregular beating of the atria. Here is the latest research.

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.