Myocardial hypoperfusion/reperfusion tolerance with exercise training in hypertension

Area of Science:

• Cardiovascular Physiology
• Exercise Science
• Molecular Cardiology

Background:

• Hypertension can induce compensated cardiac hypertrophy, potentially altering myocardial function.
• Exercise training is known to induce cardiac adaptations and may offer cardioprotection.
• The combined effects of hypertrophy and exercise on hypoperfusion-reperfusion (H/R) tolerance are not fully understood.

Purpose of the Study:

• To investigate if exercise training, when superimposed on compensated hypertrophy, enhances myocardial tolerance to H/R injury.
• To compare the effects of exercise training on H/R tolerance in normotensive (Wistar-Kyoto rats, WKY) and spontaneously hypertensive rats (SHR).

Main Methods:

• Adult female WKY and SHR rats were assigned to sedentary (SED) or exercise training (TRD) groups for 16 weeks.
• Isolated hearts were subjected to a controlled H/R protocol (75% coronary flow reduction for 17 min, followed by 30 min reperfusion).
• Cardiac function, blood pressure, heart rate, and myocardial 72-kDa heat shock protein abundance were assessed.

Main Results:

• Both WKY-TRD and SHR groups (SED and TRD) exhibited improved absolute and relative myocardial H/R tolerance compared to WKY-SED.
• Endurance training did not provide additional cardioprotection to H/R in SHR with compensated hypertrophy.
• Postreperfusion 72-kDa heat shock protein abundance was elevated in WKY-TRD and SHR groups and correlated with improved left ventricular function recovery.

Conclusions:

• Compensated hypertrophy associated with short-term hypertension and endurance training each confer individual improvements in H/R tolerance.
• Elevated 72-kDa heat shock protein is associated with the cardioprotective phenotype observed in this study.
• Superimposing exercise training on existing compensated hypertrophy does not further enhance H/R tolerance.