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Subcellular Propagation of Cardiomyocyte β-Adrenergic Activation of Calcium Uptake Involves Internal β-Receptors and AKAP7

β-adrenergic receptor (β-AR) signaling in cardiac myocytes is central to cardiac function, but spatiotemporal activation within myocytes is unresolved. In rabbit ventricular myocytes, β-AR agonists or high extracellular [Ca] were applied locally at one end, to measure β-AR signal propagation as Ca−t...

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Autores principales: Shannon, Thomas R, Bare, Dan J, Van Dijk, Sabine, Raofi, Shayan, Huynh, Tiffany N-M, Xiang, Yang K, Bossuyt, Julie, Dodge-Kafka, Kimberly L, Ginsburg, Kenneth S, Bers, Donald M
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Oxford University Press 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9125612/
https://www.ncbi.nlm.nih.gov/pubmed/35620477
http://dx.doi.org/10.1093/function/zqac020
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author Shannon, Thomas R
Bare, Dan J
Van Dijk, Sabine
Raofi, Shayan
Huynh, Tiffany N-M
Xiang, Yang K
Bossuyt, Julie
Dodge-Kafka, Kimberly L
Ginsburg, Kenneth S
Bers, Donald M
author_facet Shannon, Thomas R
Bare, Dan J
Van Dijk, Sabine
Raofi, Shayan
Huynh, Tiffany N-M
Xiang, Yang K
Bossuyt, Julie
Dodge-Kafka, Kimberly L
Ginsburg, Kenneth S
Bers, Donald M
author_sort Shannon, Thomas R
collection PubMed
description β-adrenergic receptor (β-AR) signaling in cardiac myocytes is central to cardiac function, but spatiotemporal activation within myocytes is unresolved. In rabbit ventricular myocytes, β-AR agonists or high extracellular [Ca] were applied locally at one end, to measure β-AR signal propagation as Ca−transient (CaT) amplitude and sarcoplasmic reticulum (SR) Ca uptake. High local [Ca](o), increased CaT amplitude under the pipette faster than did ISO, but was also more spatially restricted. Local isoproterenol (ISO) or norepinephrine (NE) increased CaT amplitude and SR Ca uptake, that spread along the myocyte to the unexposed end. Thus, local [Ca](i) decline kinetics reflect spatio-temporal progression of β-AR end-effects in myocytes. To test whether intracellular β-ARs contribute to this response, we used β-AR-blockers that are membrane permeant (propranolol) or not (sotalol). Propranolol completely blocked NE-dependent CaT effects. However, blocking surface β-ARs only (sotalol) suppressed only ∼50% of the NE-induced increase in CaT peak and rate of [Ca](i) decline, but these changes spread more gradually than NE alone. We also tested whether A-kinase anchoring protein 7γ (AKAP7γ; that interacts with phospholamban) is mobile, such that it might contribute to intracellular spatial propagation of β-AR signaling. We found AKAP7γ to be highly mobile using fluorescence recovery after photobleach of GFP tagged AKAP7γ, and that PKA activation accelerated AKAP7γ-GFP wash-out upon myocyte saponin-permeabilization, suggesting increased AKAP7γ mobility. We conclude that local β-AR activation can activate SR Ca uptake at remote myocyte sites, and that intracellular β-AR and AKAP7γ mobility may play a role in this spread of activation.
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spelling pubmed-91256122022-05-24 Subcellular Propagation of Cardiomyocyte β-Adrenergic Activation of Calcium Uptake Involves Internal β-Receptors and AKAP7 Shannon, Thomas R Bare, Dan J Van Dijk, Sabine Raofi, Shayan Huynh, Tiffany N-M Xiang, Yang K Bossuyt, Julie Dodge-Kafka, Kimberly L Ginsburg, Kenneth S Bers, Donald M Function (Oxf) Research Article β-adrenergic receptor (β-AR) signaling in cardiac myocytes is central to cardiac function, but spatiotemporal activation within myocytes is unresolved. In rabbit ventricular myocytes, β-AR agonists or high extracellular [Ca] were applied locally at one end, to measure β-AR signal propagation as Ca−transient (CaT) amplitude and sarcoplasmic reticulum (SR) Ca uptake. High local [Ca](o), increased CaT amplitude under the pipette faster than did ISO, but was also more spatially restricted. Local isoproterenol (ISO) or norepinephrine (NE) increased CaT amplitude and SR Ca uptake, that spread along the myocyte to the unexposed end. Thus, local [Ca](i) decline kinetics reflect spatio-temporal progression of β-AR end-effects in myocytes. To test whether intracellular β-ARs contribute to this response, we used β-AR-blockers that are membrane permeant (propranolol) or not (sotalol). Propranolol completely blocked NE-dependent CaT effects. However, blocking surface β-ARs only (sotalol) suppressed only ∼50% of the NE-induced increase in CaT peak and rate of [Ca](i) decline, but these changes spread more gradually than NE alone. We also tested whether A-kinase anchoring protein 7γ (AKAP7γ; that interacts with phospholamban) is mobile, such that it might contribute to intracellular spatial propagation of β-AR signaling. We found AKAP7γ to be highly mobile using fluorescence recovery after photobleach of GFP tagged AKAP7γ, and that PKA activation accelerated AKAP7γ-GFP wash-out upon myocyte saponin-permeabilization, suggesting increased AKAP7γ mobility. We conclude that local β-AR activation can activate SR Ca uptake at remote myocyte sites, and that intracellular β-AR and AKAP7γ mobility may play a role in this spread of activation. Oxford University Press 2022-05-05 /pmc/articles/PMC9125612/ /pubmed/35620477 http://dx.doi.org/10.1093/function/zqac020 Text en © The Author(s) 2022. Published by Oxford University Press on behalf of American Physiological Society. https://creativecommons.org/licenses/by-nc/4.0/This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (https://creativecommons.org/licenses/by-nc/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact journals.permissions@oup.com
spellingShingle Research Article
Shannon, Thomas R
Bare, Dan J
Van Dijk, Sabine
Raofi, Shayan
Huynh, Tiffany N-M
Xiang, Yang K
Bossuyt, Julie
Dodge-Kafka, Kimberly L
Ginsburg, Kenneth S
Bers, Donald M
Subcellular Propagation of Cardiomyocyte β-Adrenergic Activation of Calcium Uptake Involves Internal β-Receptors and AKAP7
title Subcellular Propagation of Cardiomyocyte β-Adrenergic Activation of Calcium Uptake Involves Internal β-Receptors and AKAP7
title_full Subcellular Propagation of Cardiomyocyte β-Adrenergic Activation of Calcium Uptake Involves Internal β-Receptors and AKAP7
title_fullStr Subcellular Propagation of Cardiomyocyte β-Adrenergic Activation of Calcium Uptake Involves Internal β-Receptors and AKAP7
title_full_unstemmed Subcellular Propagation of Cardiomyocyte β-Adrenergic Activation of Calcium Uptake Involves Internal β-Receptors and AKAP7
title_short Subcellular Propagation of Cardiomyocyte β-Adrenergic Activation of Calcium Uptake Involves Internal β-Receptors and AKAP7
title_sort subcellular propagation of cardiomyocyte β-adrenergic activation of calcium uptake involves internal β-receptors and akap7
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9125612/
https://www.ncbi.nlm.nih.gov/pubmed/35620477
http://dx.doi.org/10.1093/function/zqac020
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