Anzawa R, Seki S, Nagoshi T, Taniguchi I, Feuvray D, Yoshimura M. The role of Na+/H+ exchanger in Ca2+ overload and ischemic myocardial damage in hearts from type 2 diabetic db/db mice.
Cardiovasc Diabetol 2012;
11:33. [PMID:
22490613 PMCID:
PMC3366908 DOI:
10.1186/1475-2840-11-33]
[Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2011] [Accepted: 04/11/2012] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND
A higher increase in intracellular Na(+) via Na(+)/H(+) exchanger (NHE) during ischemia has been reported in type 2 diabetic mouse hearts. We investigated the role of NHE in inducing changes in cytoplasmic Ca(2+) concentration ([Ca(2+)](i)) and alterations in ventricular function during ischemia-reperfusion in type 2 diabetic mouse hearts.
METHODS
Hearts from male type 2 diabetic db/db (12-15 weeks old) and age-matched control db/+ mice were subjected to Langendorff perfusion and loaded with 4 μM of the Ca(2+) indicator fura-2. The hearts were exposed to no-flow ischemia for 15 minutes and then reperfused. [Ca(2+)](i) was measured by monitoring fura-2 fluorescence at 500 nm (excitation wavelengths of 340 and 380 nm), while left ventricular (LV) pressure was simultaneously measured.
RESULTS
db/db hearts exhibited a lower recovery of LV developed pressure than db/+ hearts during reperfusion following ischemia. Diastolic [Ca(2+)](i) was increased to a greater level in diabetic hearts than in the control hearts during ischemia and reperfusion. Such an increase in cytoplasmic Ca(2+) overload during ischemia-reperfusion in diabetic hearts was markedly reduced in the presence of the NHE inhibitor cariporide. This was accompanied by a significantly improved recovery of ventricular function on reperfusion, as shown by a lower increase in diastolic pressure and increased recovery of developed pressure.
CONCLUSION
NHE plays a key role in enhancing cytoplasmic Ca(2+) overload during ischemia-reperfusion and severely impairing post-ischemic cardiac function in hearts from type 2 diabetic db/db mice.
Collapse