Myocardial mitochondrial synthesis in response to various workloads.

Mitochondrial synthesis of subsarcolemmal (SS) and intermyofibrillar (IMF) mitochondria in the perfused heart was measured under four different conditions; low heart rate (HR) and low peak left ventricular systolic pressure (PLVSP), low HR and high PLVSP, high HR and low PLVSP, and high HR and high PLVSP. The SS mitochondria exhibited the greatest rate of synthesis under all conditions, although the percentage of change from simulated resting state a low HR and low PLVSP varied with the workload. These data suggest a specificity of function of mitochondria determined by subcellular localization and myocardial workload.