Effect of anabolic steroids on rat heart muscle cells. I. Intermediate filaments.
Long-term treatment of female rats with the anabolic steroid hormone Methandrostenolone results in a conspicuous increase of intermediate sized, nonmyofibrillar filaments in muscle cells of the left cardiac ventricle, as revealed by electron microscopy. These filaments, measuring 70 - 110 A in diameter, form a characteristic network at the Z-level of the sarcomere, either encircling or penetrating the Z-bands, and appear to insert into the nuclear membrane. The T-system is accompanied by the filaments adjacent to the site of the couplings. Here they are attached to subsarcolemmal electron-dense patches, which may be Z-line precursor material. The filaments may function as a cytoskeleton, to provide passive support in the mechanism of contraction and to mediate nucleo-sarcolemmal and nucleo-myofibrillar exchange.
D000818:Animals; D002467:Cell Nucleus; D005260:Female; D006321:Heart / Q000187:drug effects*; D008566:Membranes; D008696:Methandrostenolone / Q000494:pharmacology*; D008854:Microscopy, Electron; D009200:Myocardial Contraction; D009206:Myocardium / Q000473:pathology; D051381:Rats; D012508:Sarcolemma
D008696:Methandrostenolone