Catherine Carvajal, Jiajie Yan, Alma Nani, Jaime DeSantiago, Xiaoping Wan, Isabelle Deschenes, Xun Ai, Michael Fill
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引用次数: 0
Abstract
Concerted robust opening of cardiac ryanodine receptors' (RyR2) Ca2+ release 1oplasmic reticulum (SR) is fundamental for normal systolic cardiac function. During diastole, infrequent spontaneous RyR2 openings mediate the SR Ca2+ leak that normally constrains SR Ca2+ load. Abnormal large diastolic RyR2-mediated Ca2+ leak events can cause delayed after depolarizations (DADs) and arrhythmias. The RyR2-associated mechanisms underlying these processes are being extensively studied at multiple levels utilizing various model animals. Since there are well-described species-specific differences in cardiac intracellular Ca2+ handing in situ, we tested whether or not single RyR2 function in vitro retains this species specificity. We isolated RyR2-rich heavy SR microsomes from mouse, rat, rabbit, and human ventricular muscle and quantified RyR2 function using identical solutions and methods. The single RyR2 cytosolic Ca2+ sensitivity was similar across these species. However, there were significant species differences in single RyR2 mean open times in both systole and diastole-like solutions. In diastole-like solutions, single rat/mouse RyR2 open probability and frequency of long openings (> 6 ms) were similar, but these values were significantly greater than those of either single rabbit or human RyR2s. We propose these in vitro single RyR2 functional differences across species stem from the species-specific RyR2 regulatory environment present in the source tissue. Our results show the single rabbit RyR2 functional attributes, particularly in diastole-like conditions, replicate those of single human RyR2 best among the species tested.
期刊介绍:
The Journal of Membrane Biology is dedicated to publishing high-quality science related to membrane biology, biochemistry and biophysics. In particular, we welcome work that uses modern experimental or computational methods including but not limited to those with microscopy, diffraction, NMR, computer simulations, or biochemistry aimed at membrane associated or membrane embedded proteins or model membrane systems. These methods might be applied to study topics like membrane protein structure and function, membrane mediated or controlled signaling mechanisms, cell-cell communication via gap junctions, the behavior of proteins and lipids based on monolayer or bilayer systems, or genetic and regulatory mechanisms controlling membrane function.
Research articles, short communications and reviews are all welcome. We also encourage authors to consider publishing ''negative'' results where experiments or simulations were well performed, but resulted in unusual or unexpected outcomes without obvious explanations.
While we welcome connections to clinical studies, submissions that are primarily clinical in nature or that fail to make connections to the basic science issues of membrane structure, chemistry and function, are not appropriate for the journal. In a similar way, studies that are primarily descriptive and narratives of assays in a clinical or population study are best published in other journals. If you are not certain, it is entirely appropriate to write to us to inquire if your study is a good fit for the journal.