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|Title: ||Selective Modulation of Coupled Ryanodine Receptors During Microdomain Activation of Calcium/Calmodulin-Dependent Kinase II in the Dyadic Cleft|
|Authors: ||Dries, Eef|
Sipido, Karin R.
|Issue Date: ||2013|
|Citation: ||CIRCULATION RESEARCH, 113 (11), p. 1242-U149|
|Abstract: ||Rationale: In ventricular myocytes of large mammals with low T-tubule density, a significant number of ryanodine receptors (RyRs) are not coupled to the sarcolemma; cardiac remodeling increases noncoupled RyRs.
Objective: Our aim was to test the hypothesis that coupled and noncoupled RyRs have distinct microdomain-dependent modulation.
Methods and Results: We studied single myocytes from pig left ventricle. The T-tubule network was analyzed in 3-dimension (3D) to measure distance to membrane of release sites. The rising phase of the Ca2+ transient was correlated with proximity to the membrane (confocal imaging, whole-cell voltage-clamp, K5fluo-4 as Ca2+ indicator). Ca2+ sparks after stimulation were thus identified as resulting from coupled or noncoupled RyRs. We used high-frequency stimulation as a known activator of Ca2+/calmodulin-dependent kinase II. Spark frequency increased significantly more in coupled than in noncoupled RyRs. This specific modulation of coupled RyRs was abolished by the Ca2+/calmodulin-dependent kinase II blockers autocamtide-2–related inhibitory peptide and KN-93, but not by KN-92. Colocalization of Ca2+/calmodulin-dependent kinase II and RyR was not detectably different for coupled and noncoupled sites, but the F-actin disruptor cytochalasin D prevented the specific modulation of coupled RyRs. NADPH oxidase 2 inhibition by diphenyleneiodonium or apocynin, or global reactive oxygen species scavenging, also prevented coupled RyR modulation. During stimulated Ca2+ transients, frequency-dependent increase of the rate of Ca2+ rise was seen in coupled RyR regions only and abolished by autocamtide-2–related inhibitory peptide. After myocardial infarction, selective modulation of coupled RyR was lost.
Conclusions: Coupled RyRs have a distinct modulation by Ca2+/calmodulin-dependent kinase II and reactive oxygen species, dependent on an intact cytoskeleton and consistent with a local Ca2+/reactive oxygen species microdomain, and subject to modification with disease.|
|ISI #: ||000330353100011|
|Type: ||Journal Contribution|
|Validation: ||ecoom, 2015|
|Appears in Collections: ||Research publications|
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