Abstract
To the Editor: In a recent article, MacDonnell et al1 reported that protein kinase A (PKA) phosphorylation of ryanodine receptor (RyR2) (the Ca2+ release channel of the sarcoplasmic reticulum [SR]) at Ser2808/09 site does not have a major role in the sympathetic nervous system (SNS) regulation of cardiac function. This conclusion was based on comparing the effect of isoproterenol on ventricular performance, in vivo, in isolated hearts and myocytes, in wild-type mice and in a genetically modified mouse in which Ser2808 of RyR2 was replaced by alanine (S2808A) to prevent PKA-mediated phosphorylation at this site. Isoproterenol produced an increase in cardiac function both in vivo and in isolated hearts, as well as an enhancement in the L-type Ca2+ current ( I CaL), the amplitude of the Ca2+ transient and the excitation–contraction coupling (ECC) gain in isolated myocytes, which were not significantly different between wild-type and …
Highlights
To the Editor: In a recent article, MacDonnell et al[1] reported that protein kinase A (PKA) phosphorylation of ryanodine receptor (RyR2) at Ser2808/09 site does not have a major role in the sympathetic nervous system (SNS) regulation of cardiac function
We have previously demonstrated the lack of functionality of the PKA-dependent phosphorylation of RyR2 at Ser2808/09.2 In perfused rat hearts, we showed that the isoproterenol-induced phosphorylation of RyR2 was associated with an enhancement of the [3H]-ryanodine binding and the velocity of fast Ca2ϩ release in SR vesicles from the same hearts
The purpose of our letter is to point out, in the first place, an omission of the authors in their discussion that could lead to the erroneous acceptance that Ser2808/09 is the only RyR2 site by which isoproterenol can alter the function of the SR Ca2ϩ release channel
Summary
To the Editor: In a recent article, MacDonnell et al[1] reported that protein kinase A (PKA) phosphorylation of ryanodine receptor (RyR2) (the Ca2ϩ release channel of the sarcoplasmic reticulum [SR]) at Ser2808/09 site does not have a major role in the sympathetic nervous system (SNS) regulation of cardiac function. We have previously demonstrated the lack of functionality of the PKA-dependent phosphorylation of RyR2 at Ser2808/09.2 In perfused rat hearts, we showed that the isoproterenol-induced phosphorylation of RyR2 was associated with an enhancement of the [3H]-ryanodine binding and the velocity of fast Ca2ϩ release in SR vesicles from the same hearts.
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