TENSILE-STRENGTH AND DILATATIONAL ELASTICITY OF GIANT SARCOLEMMAL VESICLES SHED FROM RABBIT MUSCLE

1. Mechanical properties of the surface membrane of skeletal muscle we re deter mined on sarcolemmal vesicles (mean diameter, 71 mu m) shed b y rabbit psoas muscle swelling in 140 mM KCl containing collagenase. 2 . Vesicles were stressed by partial aspiration into parallel bore pipe ttes. The isotropic membrane tension so created caused an increase in membrane area which expresses itself in an elongation of the vesicle p rojection into the pipette. 3. For individual vesicles, a linear relat ionship between membrane tension and membrane area increase was found up to the point when the vesicle burst, i.e. sarcolemmal vesicles beha ved as perfectly elastic structures. 4. The maximum tension sarcolemma l vesicles could sustain before bursting was 12.4 +/- 0.2 mN m(-1) (me dian +/- 95% confidence interval), and the corresponding fractional in crease in membrane area was 0.026 +/- 0.005 (median +/- 95% confidence interval). The elastic modulus of area expansion was 490 +/- 88 mN m( -1) (mean +/- S.D.). 5. In conformity with cited comparable work on re d blood cells and artificial lipid vesicles, the strength and area ela sticity of the skeletal muscle membrane are considered properties of t he fluid lipid matrix of the membrane and of the degree to which tile bilayer is perturbed by lipid-protein interaction.