Isolated neonatal rat papillary muscles: a new model to translate neonatal rat myocyte signaling into contractile mechanics

Abstract

Isolated cardiac tissue allows investigators to study mechanisms underlying normal and pathological conditions, which would otherwise be difficult or impossible to perform in vivo. Cultured neonatal rat ventricular cardiac myocytes (NRVM) are widely used to study signaling and growth mechanisms in the heart, primarily due to the versatility, economy, and convenience of this in vitro model. However, the lack of a well‐defined longitudinal cellular axis greatly hampers the ability to measure contractile function in these cells, and therefore to associate signaling with mechanical function. In these methods, we demonstrate that this limitation can be overcome by using papillary muscles isolated from neonatal rat hearts. In the methods we describe procedures for isolation of right ventricular papillary muscles from 3‐day‐old neonatal rats and effects of mechanical and humoral stimuli on contraction and relaxation properties of these tissues.

Cardiomyocytes cultured on mechanically compliant substrates, but not on conventional culture devices, exhibit prominent mitochondrial dysfunction due to reactive oxygen species and insulin resistance under high glucose

“…Primary cells lose their original phenotype rather quickly once they are isolated [ 26 ]. Neonatal rat cardiomyocytes are excellent tools for studying a wide variety of processes such as apoptosis, oxidative stress, hypertrophic growth, signal transduction, and transcriptional regulation, which could be difficult or even impossible to conduct in vivo [ 28 – 30 ]. The value of these cells has recently increased even more by co-culturing them with non-myocytes or forming three-dimensional scaffolds with various matrix proteins, which enables them to form functional cardiac tissues after several days in culture [ 31 ].…”

Investigating the role of phosphorylated regulatory light chains during heart failure progression

“…The regularity in shape of papillary muscles makes it easier to obtain viable muscle segments of close-to-equal dimensions. Also, it is established that papillary muscles are responsive to external stimulations (electrical, mechanical and pharmacologic) making it a useful model for cardiac muscle contractile experimentations (252,253). More importantly, the contractility (or functionality) of papillary fibres correlates with cardiac function.…”