Load-dependent effects of apelin on murine cardiomyocytes

Abstract

The apelin peptide is described as one of the most potent inotropic agents, produced endogenously in a wide range of cells, including cardiomyocytes. Despite positive effects on cardiac contractility in multicellular preparations, as well as indications of cardio-protective actions in several diseases, its effects and mechanisms of action at the cellular level are incompletely understood.Here, we report apelin effects on dynamic mechanical characteristics of single ventricular cardiomyocytes, isolated from mouse models (control, apelin-deficient [Apelin-KO], apelin-receptor KO mouse [APJ-KO]), and rat. Dynamic changes in maximal velocity of cell shortening and relaxation were monitored. In addition, more traditional indicators of inotropic effects, such as maximum shortening (in mechanically unloaded cells) or peak force development (in auxotonic contracting cells, preloaded using the carbon fibre technique) were studied.The key finding is that, using Apelin-KO cardiomyocytes exposed to different preloads with the 2-carbon fibre technique, we observe a lowering of the slope of the end-diastolic stress-length relation in response to 10 nM apelin, an effect that is preload-dependent. This suggests a positive lusitropic effect of apelin, which could explain earlier counter-intuitive findings on an apelin-induced increase in contractility occurring without matching rise in oxygen consumption.

A novel cyclic biased agonist of the apelin receptor, MM07, is disease modifying in the rat monocrotaline model of pulmonary arterial hypertension

“…Apelin receptor signalling is known to increase cardiac contractility and output (Brame et al, 2015;Maguire et al, 2009;Szokodi et al, 2002), possibly by activating myosin light chain kinase to increase myofilament calcium sensitivity (Perjés et al, 2014) and by a positive lusitropic effect (Peyronnet et al, 2017), so the enhanced cardiac performance does not require an increase in oxygen consumption (Charo et al, 2009). Apelin receptor signalling is known to increase cardiac contractility and output (Brame et al, 2015;Maguire et al, 2009;Szokodi et al, 2002), possibly by activating myosin light chain kinase to increase myofilament calcium sensitivity (Perjés et al, 2014) and by a positive lusitropic effect (Peyronnet et al, 2017), so the enhanced cardiac performance does not require an increase in oxygen consumption (Charo et al, 2009).…”

“…Previous studies have proposed possible explanations for the observed benefits of MM07. Apelin receptor signalling is known to increase cardiac contractility and output (Brame et al, 2015;Maguire et al, 2009;Szokodi et al, 2002), possibly by activating myosin light chain kinase to increase myofilament calcium sensitivity (Perjés et al, 2014) and by a positive lusitropic effect (Peyronnet et al, 2017), so the enhanced cardiac performance does not require an increase in oxygen consumption (Charo et al, 2009). MM07-induced haemodynamic improvement was confirmed by invasive right heart catheterisation.…”

Ischemia Enhances the Acute Stretch-Induced Increase in Calcium Spark Rate in Ventricular Myocytes

“…It may relate to methodological differences or differences in data handling. Our experiments involved the stretch of ventricular myocytes using 10 µm diameter compliant carbon fibers, which stick to the cells through biophysical interactions (Peyronnet et al, 2017). The previous work from Prosser et al (2011) used 20 µm stiff glass rods adhered to the cells with a biological adhesive (Myotak, composed of laminin, entactin, heparin sulfate proteoglycan, gentamicin, Dulbecco's Modified Eagle Medium, collagen IV, Alexa Fluor-647 conjugated to bovine serum albumin, and an inert alumina silica aggregate with a diameter of 1 µm, dissolved in 100 µM BSA).…”

“…Cells were placed on coverslips coated with poly-2-hydroxyethyl methacrylate (poly-HEMA; Sigma-Aldrich, Tokyo, Japan) to prevent cellular adhesion. Carbon fibers (10 µm in diameter) mounted in glass capillaries that adhere to isolated cells through biophysical interactions (Peyronnet et al, 2017) were attached to either end of an individual cell. For experiments examining the effect of stretch on Ca 2+ sparks, one "compliant" (1.2 mm) and one "stiff " (0.6 mm) carbon fiber were used, while for the ROS experiments two compliant (1.2 mm) carbon fibers were used (Tsukuba Material Information Laboratory, Tsukuba, Japan).…”

Potassium channel-based optogenetic silencing

“…To this end, cardiomyocytes were imaged with a MyoCam-S camera (IonOptix) on an inverted microscope (DM IRBE, Leica Microsystems). Sarcomere length was calculated in real time by a Fast Fourier Transform of the power spectrum of the striation pattern (IonWizard, IonOptix) 61 . Cells were field stimulated at 14 V/0.25 Hz with a Myopacer (IonOptix).…”