Inhibition of BKCa channels protects neonatal hearts against myocardial ischemia and reperfusion injury

Shridhar Sanghvi; Kalina Szteyn; Devasena Ponnalagu; Divya Sridharan; Alexander Lam; Inderjot Hansra; Ankur Chaudhury; Uddalak Majumdar; Andrew R Kohut; Shubha Gururaja Rao; Mahmood Khan; Vidu Garg; Harpreet Singh

doi:10.1038/s41420-022-00980-z

Inhibition of BK_Ca channels protects neonatal hearts against myocardial ischemia and reperfusion injury

Cell Death Discov. 2022 Apr 7;8(1):175. doi: 10.1038/s41420-022-00980-z.

Authors

Shridhar Sanghvi^{1

2}, Kalina Szteyn¹, Devasena Ponnalagu¹, Divya Sridharan³, Alexander Lam⁴, Inderjot Hansra¹, Ankur Chaudhury⁴, Uddalak Majumdar⁵, Andrew R Kohut^{4

6}, Shubha Gururaja Rao⁷, Mahmood Khan^{1

3}, Vidu Garg^{5

8}, Harpreet Singh^{9

10}

Affiliations

¹ Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH, USA.
² Department of Molecular Cellular and Developmental Biology, The Ohio State University, Columbus, OH, USA.
³ Department of Emergency Medicine, Wexner Medical Center, The Ohio State University, Columbus, OH, USA.
⁴ Department of Internal Medicine, Drexel University College of Medicine, Philadelphia, PA, USA.
⁵ Center for Cardiovascular Research and The Heart Center, Nationwide Children's Hospital, Columbus, OH, USA.
⁶ Division of Cardiology, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
⁷ Department of Pharmaceutical and Biomedical Sciences, The Raabe College of Pharmacy, Ohio Northern University, Ada, OH, USA.
⁸ Department of Pediatrics, The Ohio State University, Columbus, OH, USA.
⁹ Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH, USA. Harpreet.singh@osumc.edu.
¹⁰ Department of Molecular Cellular and Developmental Biology, The Ohio State University, Columbus, OH, USA. Harpreet.singh@osumc.edu.

Abstract

BK_Ca channels are large-conductance calcium and voltage-activated potassium channels that are heterogeneously expressed in a wide array of cells. Activation of BK_Ca channels present in mitochondria of adult ventricular cardiomyocytes is implicated in cardioprotection against ischemia-reperfusion (IR) injury. However, the BK_Ca channel's activity has never been detected in the plasma membrane of adult ventricular cardiomyocytes. In this study, we report the presence of the BK_Ca channel in the plasma membrane and mitochondria of neonatal murine and rodent cardiomyocytes, which protects the heart on inhibition but not activation. Furthermore, K⁺ currents measured in neonatal cardiomyocyte (NCM) was sensitive to iberiotoxin (IbTx), suggesting the presence of BK_Ca channels in the plasma membrane. Neonatal hearts subjected to IR when post-conditioned with NS1619 during reoxygenation increased the myocardial infarction whereas IbTx reduced the infarct size. In agreement, isolated NCM also presented increased apoptosis on treatment with NS1619 during hypoxia and reoxygenation, whereas IbTx reduced TUNEL-positive cells. In NCMs, activation of BK_Ca channels increased the intracellular reactive oxygen species post HR injury. Electrophysiological characterization of NCMs indicated that NS1619 increased the beat period, field, and action potential duration, and decreased the conduction velocity and spike amplitude. In contrast, IbTx had no impact on the electrophysiological properties of NCMs. Taken together, our data established that inhibition of plasma membrane BK_Ca channels in the NCM protects neonatal heart/cardiomyocytes from IR injury. Furthermore, the functional disparity observed towards the cardioprotective activity of BK_Ca channels in adults compared to neonatal heart could be attributed to their differential localization.

Abstract

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