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The volume of the T‐system and its association with the sarcoplasmic reticulum in slow muscle fibres of the frog
Author(s) -
Flitney F. W.
Publication year - 1971
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1971.sp009569
Subject(s) - endoplasmic reticulum , chemistry , biophysics , anatomy , contraction (grammar) , biology , biochemistry , endocrinology
1. A study has been made of the T‐system and sarcoplasmic reticulum (SR) in slow muscle fibres of the frog, Rana temporaria . 2. The size of the T‐system was measured by an autoradiographic method, using tritium‐labelled albumin as a marker. Its volume, expressed as a fraction of that of the fibre, was found to be 1·8 × 10 −3 , as compared with a figure of 3·9 × 10 −3 for the T‐system in a twitch fibre. 3. The spatial distribution of the T‐tubules, and their association with the SR, was studied with the electron microscope, employing ferritin and the enzyme peroxidase as markers. The observations show ( a ) the tubules form a three dimensional, rather than transverse, network and ( b ) the area of triadic (and diadic) contact with the SR is 5‐10 × smaller than in a twitch fibre. 4. The possibility that the T‐system and SR of the slow fibre participate in linking membrane excitation with contraction is discussed in the light of these findings.