Dystrophin, a 427 kD membrane-associated structural protein in muscle cells, is thought to confer strength to the myofiber sarcolemma and protect the membrane from rupture during the stresses of contraction. Dystrophin is absent in muscle cells from Duchenne muscular dystrophy (DMD) patients and mdx mice, a DMD model. Dystrophic muscle membranes undergo more frequent transient, nonlethal tears than normal cell membranes, especially during exercise. In addition, the mean open probability of a background (``leak'') calcium channel is higher in dystrophic muscle cells, which leads to higher intracellular free calcium levels. Because elevated calcium levels may contribute to the eventual necrosis of muscle cells in DMD, we examined the possibility that the history of sarcolemmal rupture at a specific location on the membrane affects the open probability of nearby calcium leak channels. Membrane ruptures left by the excision of cell-attached patch-clamp electrodes were used to mimic natural tears. Patches made within 5 microns of excision sites contained channels with a fourfold greater mean open probability than channels in patches 50 μm away from ruptures. The increased leak channel activity near ruptures was seen continuously through the duration of the recordings and was not seen if the rupture was made in the presence of the protease inhibitor leupeptin. Calcium background channels proteolytically activated near ruptures, perhaps in a calcium-dependent manner, may thus be the lasting consequence of the weaker dystrophic sarcolemma, leading to chronically raised intracellular free calcium, increased calcium-dependent proteolysis and, eventually, necrosis.
The Journal of Membrane Biology – Springer Journals
Published: Jul 15, 2000
It’s your single place to instantly
discover and read the research
that matters to you.
Enjoy affordable access to
over 18 million articles from more than
15,000 peer-reviewed journals.
All for just $49/month
Query the DeepDyve database, plus search all of PubMed and Google Scholar seamlessly
Save any article or search result from DeepDyve, PubMed, and Google Scholar... all in one place.
Get unlimited, online access to over 18 million full-text articles from more than 15,000 scientific journals.
Read from thousands of the leading scholarly journals from SpringerNature, Elsevier, Wiley-Blackwell, Oxford University Press and more.
All the latest content is available, no embargo periods.
“Hi guys, I cannot tell you how much I love this resource. Incredible. I really believe you've hit the nail on the head with this site in regards to solving the research-purchase issue.”Daniel C.
“Whoa! It’s like Spotify but for academic articles.”@Phil_Robichaud
“I must say, @deepdyve is a fabulous solution to the independent researcher's problem of #access to #information.”@deepthiw
“My last article couldn't be possible without the platform @deepdyve that makes journal papers cheaper.”@JoseServera