Auckland Bioengineering Institute

Trabecula muscle rig


The Auckland Bioengineering Institute has developed a superfused muscle bath, suitable to determine both passive and active mechanical properties of cardiac trabeculae (~2 mm long x 200 um diameter).

These properties are determined by mechanically perturbing one end of the trabeculae while measuring the resulting force changes at the opposing end. Stiffness is determined via small amplitude high frequency displacement (Queensgate oscillator), while compliance (stress-muscle length) is determined via larger and slower displacement (Physik Instrumente DC mike).

Force is measured by strain gauge (10 uN resolution). The 40 ul muscle bath is constructed of two coverslips spaced at 2 mm attached to a brass base. The brass base is temperature regulated via a Peltier thermode. The coverslip walls of the bath offer an optical path through which a 50 times objective captures a 120 x 90 um subimage of the trabeculae. A Labview program uses this subimage to calculate the average sarcomere extension in the viewable area.

Constitutive laws can be constructed from this data, for use in more complex whole heart finite element models.