Mechanoelectrical feedback, defined as changes in mechanical state that precede and alter transmembrane potential, may have potential importance in understanding the role of altered load and contractility in the initiation and modulation of ventricular arrhythmias. To assess the independent effects of preload and contractility on myocardial excitability and action potential duration, we determi...

THERE HAS BEEN much recent interest by clinical cardiologists in the question of myocardial "contractility" or "contractile state." To the clinician, the quest for a measure of "contractility" or "contractile state" becomes the quest for an early indication of myocardial disease that may be of prognostic value and open up the possibility of preventive measures to forestall serious myocardial di...

KEY POINTS The strength, functional significance and origins of parasympathetic innervation of the left ventricle remain controversial. This study tested the hypothesis that parasympathetic control of left ventricular contractility is provided by vagal preganglionic neurones of the dorsal motor nucleus (DVMN). Under β-adrenoceptor blockade combined with spinal cord (C1) transection (to remove s...

Phospholemman (PLM) regulates cardiac Na(+)/Ca(2+) exchanger (NCX1) and Na(+)-K(+)-ATPase in cardiac myocytes. PLM, when phosphorylated at Ser(68), disinhibits Na(+)-K(+)-ATPase but inhibits NCX1. PLM regulates cardiac contractility by modulating Na(+)-K(+)-ATPase and/or NCX1. In this study, we first demonstrated that adult mouse cardiac myocytes cultured for 48 h had normal surface membrane ar...

BACKGROUND Prostaglandins (PGs) are important stimulators of uterine contractility. Limited data are available at present on the effects of different PGs on uterine contractility, measured using intraluminal pressure changes in the complete uterus. The goal of this study was to assess dynamic changes in uterine contractility and peristalsis in response to PGs in comparison with the effects of o...

BACKGROUND Actomyosin contractility is the major cellular force driving changes in cell and tissue shape. A principal regulator of contractility is the small GTPase RhoA. External mechanical forces have been shown to impact RhoA activity and cellular contractility. However, the mechanotransduction pathway from external forces to actomyosin contractility is poorly understood. RESULTS Here, we ...

BACKGROUND Ovarian sex hormones (OSHs) are implicated in cardiovascular function. It has been shown that OSHs play an important role in the long term regulation of cardiac sarcoplasmic reticulum (SR) function and contractility, although early effects of OSHs deprivation on myocardial contractility have not yet been determined. This study evaluated the early and late effects of OSHs deficiency o...