The Z-band lattice in skeletal muscle before, during and after tetanic contraction.
Electron micrographs and optical diffraction patterns of the Z-band were studied in rat soleus muscle fixed before, during, and after tetanic contraction. We compared the morphology (small square or basketweave pattern) and dimensions of the Z-lattice of control and tetanized muscles near rest length. Z-bands of muscle fixed at rest and of muscle allowed to rest after a tetanic contraction exhibited the small square pattern. Z-bands from muscle fixed during tetanic contraction exhibited the basketweave pattern. Concomitant with the transition to basketweave, we observed an average increase of 20% in spacing between the axial filaments of the Z-lattice. Optical diffraction measurements of the A-band d10 spacing revealed that the Z/A ratio remained constant during the transition. We have modelled the small square to basketweave transformation as resulting from a change of curvature of constant length cross-connecting Z-filaments when the axial filaments increase their separation.
D000818:Animals; D008854:Microscopy, Electron; D009119:Muscle Contraction; D009129:Muscle Tonus; D009132:Muscles / Q000648:ultrastructure*; D051381:Rats; D011919:Rats, Inbred Strains; D012518:Sarcomeres