BACKGROUND After cardioversion of atrial fibrillation (AF), the contractile function of the atria is temporarily impaired. Although this has significant clinical implications, the underlying cellular mechanisms are poorly understood. METHODS AND RESULTS Forty-nine consecutive patients submitted for mitral valve surgery were investigated. Twenty-three were in persistent AF (>/=3 months); the o...

Inclusion of phospholipase D (Streptomyces chromofuscus, 5 U/ml) in the medium perfusing rabbit papillary muscles increased peak force development by 78% and peak dF/dt by 89%. The maximal contractile response occurred 40-50 minutes after addition of the enzyme to the perfusate. As peak contractile response developed, aftercontractions appeared in most muscles. The inotropic response was slowly...

Background—Myocardial contractile response to 1and 2-adrenergic receptor (AR) stimulation is severely impaired in chronic heart failure, in which Gi signaling and the ratio of 2/ 1 are often increased. Because 2-AR but not 1-AR couples to Gs and Gi with the Gi coupling negating the Gs-mediated contractile response, we determined whether the heart failure–associated augmentation of Gi signaling ...

OBJECTIVE Over half of twin pregnancies in US and UK deliver prematurely but the reasons for this are unclear. The contractility of myometrium from twin pregnancies has not been directly investigated. The objective of this research was to determine if there are differences in the contractile activity and response to oxytocin, between myometrium from singleton and twin pregnancies, across a rang...

We previously reported that in the endothelium-denuded rat aorta, lysophosphatidylcholine (LPC) potentiates the contractile responses induced by high-K(+), UK14,304 (a selective alpha(2)-adrenoceptor agonist), and phorbol ester with an associated tyrosine-phosphorylation of proteins. To further investigate this phenomenon, we examined the effects of extracellular-signal-regulated protein kinase...

Background: Uterine bleeding is an important side effect of cesarean section which is due to non contractile uterine. The aim of this study was to compare the effect of 10% dextrose (IV infusion) and 40 IU/L oxytocin (IV infusion) on uterine contraction. Materials and Methods: This research was a double-blinded randomized clinical trial (RCT) study. 120 women were equally included in the tw...

The contractile response of rabbit renal arteries and canine tibial arteries to prostaglandins A2, B2, F2alpha, E1, E2, D2, and B1 was associated with a reduction in total sulfhydryl group content of smooth muscle. The total sulfhydryl content of rabbit renal and canine tibial arteries and was not affected by norepinephrine or potassium chloride. Reduction of disulfide groups with dithiothreito...

We have studied the effects of the sulfhydryl reagents on contractile responses, using either electrically stimulated single muscle fibers or short muscle fibers that were voltage-clamped with a two-microelectrode voltage-clamp technique that allows the fiber tension in response to membrane depolarization to be recorded. The sulfhydryl inhibitors para-chloromercuribenzoic acid (PCMB) and parahy...

AIMS Lack of response to cardiac resynchronization therapy (CRT) may be due to the presence of significant amount of scar or fibrotic tissue at myocardial level. This study sought to investigate the potential impact of myocardial contractile reserve as assessed during exercise echocardiography on left ventricular (LV) reverse remodelling (decrease in LV end-systolic volume > or =15% after 6 mon...

The aim of the present study was to investigate the effects of high concentrations of KCl in releasing noradrenaline from sympathetic nerves and its actions on postsynaptic alpha-adrenoceptors. We measured the isotonic contractions induced by KCl in the isolated rat anococcygeus muscle under different experimental conditions. The contractile responses induced by KCl were inhibited by alpha-adre...