Premium
Stimulated Release of Phosphatidylinositol Phosphodiesterase in an Isolated Phrenic Nerve‐Diaphragm Preparation
Author(s) -
Smith Margaret E.,
Shute Janis K.,
MorganHarrison Kay
Publication year - 1987
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1987.tb05692.x
Subject(s) - phrenic nerve , phosphatidylinositol , diaphragm (acoustics) , phosphodiesterase , motor endplate , neuromuscular junction , stimulation , cytosol , neuromuscular transmission , chemistry , anatomy , motor nerve , biology , enzyme , endocrinology , biochemistry , respiratory system , neuroscience , signal transduction , physics , acoustics , loudspeaker
Electrical stimulation of the phrenic nerve in an isolated nerve‐diaphragm preparation resulted in the release of phosphatidylinositol phosphodiesterase into the organ bath. The released enzyme was Ca 2+ ‐dependent and exhibited two pH optima. The enzyme was released in response to nerve stimulation even in the presence of d ‐tubocurarine in concentrations that block neuromuscular transmission, and was not therefore released from the muscle as a consequence of its contractile activity. Phosphatidylinositol phosphodiesterase activity was determined in the soluble cytosol fractions prepared from different regions of skeletal muscles and from normal peripheral nerves and nerves that were degenerating after transection. The specific activity of the enzyme in the cytosol from the endplate‐rich region of the diaphragm was significantly greater than that in cytosol from either the endplate‐free region of the diaphragm or from the phrenic nerve. In degenerating nerve the activity of the enzyme was greater in the distal stump than in the proximal stump at 36 h after nerve section. Possible roles for released phosphatidylinositol phosphodiesterase at the neuromuscular junction are discussed.