Fasudil prevents KATP channel-induced improvement in postischemic functional recovery

Area of Science:

• Cardiovascular Physiology
• Molecular Cardiology
• Cell Signaling

Background:

• ATP-dependent potassium (K(ATP)) channels are known to enhance myocardial recovery post-ischemia.
• The precise molecular mechanisms underlying K(ATP) channel-mediated cardioprotection are not fully understood.
• RhoA, a GTPase, influences cellular processes relevant to K(ATP) channel function.

Purpose of the Study:

• To investigate whether rho kinase (ROCK), a key effector of RhoA, is essential for K(ATP) channel-induced cardioprotection.
• To elucidate the role of ROCK in the beneficial effects of K(ATP) channel activation on the ischemic heart.

Main Methods:

• Utilized isolated perfused rat hearts subjected to a model of ischemia-reperfusion.
• Compared mechanical function and high-energy phosphate levels ((31)P NMR) across four experimental groups: untreated, K(ATP) channel activation (pinacidil), ROCK inhibition (fasudil), and combined treatment.
• Administered pinacidil to activate K(ATP) channels and fasudil to inhibit ROCK.

Main Results:

• Pinacidil treatment significantly improved post-ischemic mechanical recovery, indicated by increased left ventricular diastolic pressure (LVDP).
• Fasudil alone did not alter reperfusion LVDP but completely abolished the protective effects of pinacidil.
• ROCK inhibition also led to substantial attenuation of post-ischemic energetic recovery.

Conclusions:

• Rho kinase (ROCK) activity is a necessary component for K(ATP) channel-induced cardioprotection.
• These findings support the hypothesis that ROCK signaling plays a critical role in mediating the beneficial effects of K(ATP) channel activation on the heart during and after ischemia.