Response to Letter Regarding Article “Inositol 1,4,5-Trisphosphate Receptors and Human Left Ventricular Myocytes”
This article requires a subscription to view the full text. If you have a subscription you may use the login form below to view the article. Access to this article can also be purchased.
We thank Drs Heidrich and colleagues for their comments on our study discussing the role of inositol 1,4,5-trisphosphate receptors (IP3Rs) in ventricular myocytes.1 We documented that IP3Rs are present and operative in the rodent and human ventricular myocardium and that stimulation of Gαq-protein-coupled receptors promotes IP3R-mediated Ca2+ release. This adaptation provides inotropic support but favors electric instability.
As pointed out by Dr Heidrich and colleagues, our report did not address the contribution of endogenous IP3R-regulatory proteins2 to the electrophysiological and contractile properties of ventricular myocytes. Specifically, they raised the possibility that chromogranin B, a sarcoplasmic reticulum Ca2+-binding protein, interacts with IP3Rs3 and modulates myocyte behavior after Gαq-protein-coupled receptor stimulation. The relationship between chromogranin B and IP3Rs …