Al Kury LT, Sydorenko V, Smail MMA, Qureshi MA, Shmygol A, Papandreou D, Singh J, Howarth FC. Calcium signaling in endocardial and epicardial ventricular myocytes from streptozotocin-induced diabetic rats.
J Diabetes Investig 2021;
12:493-500. [PMID:
33112506 PMCID:
PMC8015823 DOI:
10.1111/jdi.13451]
[Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 10/08/2020] [Accepted: 10/22/2020] [Indexed: 12/16/2022] Open
Abstract
AIMS/INTRODUCTION
Abnormalities in Ca2+ signaling have a key role in hemodynamic dysfunction in diabetic heart. The purpose of this study was to explore the effects of streptozotocin (STZ)-induced diabetes on Ca2+ signaling in epicardial (EPI) and endocardial (ENDO) cells of the left ventricle after 5-6 months of STZ injection.
MATERIALS AND METHODS
Whole-cell patch clamp was used to measure the L-type Ca2+ channel (LTCC) and Na+ /Ca2+ exchanger currents. Fluorescence photometry techniques were used to measure intracellular free Ca2+ concentration.
RESULTS
Although the LTCC current was not significantly altered, the amplitude of Ca2+ transients increased significantly in EPI-STZ and ENDO-STZ compared with controls. Time to peak LTCC current, time to peak Ca2+ transient, time to half decay of LTCC current and time to half decay of Ca2+ transients were not significantly changed in EPI-STZ and ENDO-STZ myocytes compared with controls. The Na+ /Ca2+ exchanger current was significantly smaller in EPI-STZ and in ENDO-STZ compared with controls.
CONCLUSIONS
STZ-induced diabetes resulted in an increase in amplitude of Ca2+ transients in EPI and ENDO myocytes that was independent of the LTCC current. Such an effect can be attributed, at least in part, to the dysfunction of the Na+ /Ca2+ exchanger. Additional studies are warranted to improve our understanding of the regional impact of diabetes on Ca2+ signaling, which will facilitate the discovery of new targeted treatments for diabetic cardiomyopathy.
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