The human heart is a very efficient machine that beats on average about 80 times per minute for the entire lifespan of its owner. Direct observations of rat cardiomyocytes, the individual muscle units of the heart, with a high-resolution light microscope have revealed that the microtubules (wavy lines pictured here in red) buckle during each contraction, and act as load bearing springs that complement the contractile apparatus. The microtubules help return the myocyte back to its original shape after contraction. Chemical alterations in the microtubules interfere with the delicate balance with the contractile network, and such changes are thought to contribute to heart disease.
Cardiomyocytes were labelled with a fluorescent probe that binds to microtubules in living cells and imaged with a high-speed Airy scan microscope. The microtubules are 25 nanometers in diameter.
Benjamin L. Prosser, PhD, Dept. of Physiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA.