Cookies on this website

We use cookies to ensure that we give you the best experience on our website. If you click 'Accept all cookies' we'll assume that you are happy to receive all cookies and you won't see this message again. If you click 'Reject all non-essential cookies' only necessary cookies providing core functionality such as security, network management, and accessibility will be enabled. Click 'Find out more' for information on how to change your cookie settings.

BACKGROUND: Na(+)/H(+) exchange inhibition with HOE642 (cariporide) improves postischemic recovery of cardiac function, but the mechanisms of action remain speculative. Because Na(+)/H(+) exchange is activated on reperfusion, it was hypothesized that its inhibition delays realkalinization and decreases intracellular Na(+) and, via Na(+)/Ca(2+) exchange, Ca(2+) overload. Attenuated Ca(2+) overload and prolonged acidosis are known to be cardioprotective. METHODS AND RESULTS: Left ventricular developed and end-diastolic pressures were measured in isolated buffer-perfused rat hearts subjected to 30 minutes of no-flow ischemia and 30 minutes of reperfusion (37 degrees C) with or without 1 micromol/L HOE642 added to the perfusate 15 minutes before ischemia. Intracellular Ca(2+) concentration ([Ca(2+)](i)) and pH(i) were measured with aequorin (n=10 per group) and (31)P NMR spectroscopy (n=6 per group), respectively. HOE642 did not affect preischemic mechanical function, [Ca(2+)](i), or pH(i). Mechanical recovery after 30 minutes of reperfusion was substantially improved with HOE642: left ventricular developed pressure (in percent of preischemic values) was 92+/-3 versus 49+/-7 and left ventricular end-diastolic pressure was 16+/-3 versus 46+/-5 mm Hg (P<0.05 for HOE642-treated versus untreated hearts). End-ischemic [Ca(2+)](i) was significantly lower in HOE642-treated than in untreated hearts (1.04+/-0.06 versus 1.84+/-0. 02 micromol/L, P<0.05). Maximal intracellular Ca(2+) overload during the first 60 seconds of reperfusion was attenuated with HOE642 compared with untreated hearts: 2.0+/-0.3 versus 3.2+/-0.3 micromol/L (P<0.05). pH(i) was not different at end ischemia ( approximately 5.9+/-0.05). Realkalinization was similar in the first 90 seconds of reperfusion and significantly delayed in the next 3 minutes (eg, 6.8+/-0.07 in HOE642-treated hearts compared with 7. 2+/-0.07 in untreated hearts; P<0.05). CONCLUSIONS: HOE642 improves postischemic recovery by reducing Ca(2+) overload during ischemia and early reperfusion and by prolonging postischemic acidosis.

Type

Journal article

Journal

Circulation

Publication Date

13/06/2000

Volume

101

Pages

2749 - 2755

Keywords

Acidosis, Aequorin, Animals, Anti-Arrhythmia Agents, Calcium, Guanidines, Hydrogen-Ion Concentration, In Vitro Techniques, Magnetic Resonance Spectroscopy, Male, Myocardial Ischemia, Myocardial Reperfusion Injury, Myocardium, Phosphorus Isotopes, Rats, Rats, Wistar, Sodium-Hydrogen Exchangers, Sulfones, Ventricular Function, Left