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SUBACUTE NEUROPATHIC EFFECTS OF DIISOPROPYLFLUOROPHOSPHATE AT THE CAT SOLEUS NEUROMUSCULAR JUNCTION
Author(s) -
BAKER T.,
GLAZER ELLYN,
LOWNDES H. E.
Publication year - 1977
Publication title -
neuropathology and applied neurobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.538
H-Index - 95
eISSN - 1365-2990
pISSN - 0305-1846
DOI - 10.1111/j.1365-2990.1977.tb00598.x
Subject(s) - neuromuscular junction , soleus muscle , cholinesterase , motor nerve , sprouting , medicine , motor endplate , cats , anatomy , anesthesia , chemistry , endocrinology , biology , skeletal muscle , neuroscience , botany
Subacute neuropathic effects of diisopropylfluorophosphate at the cat soleus neuromuscular junction Diisopropylfluorophosphate (DFP), an organophosphate cholinesterase inhibitor, causes a neuromuscular dysfunction 1–3 days after exposure (subacute) as well as a delayed (21 day post‐drug) peripheral neuropathy. The effects of DFP were studied in cats given 2 mg/kg DFP into one femoral artery. The contractile strength of the soleus muscle evoked by indirect, single stimulation was reduced 4 h later and fell to 16% of normal after 3 days; by 7 days post‐drug the contractile strength recovered to 76% of control values. A pre‐junctional neuromuscular defect was investigated by assessing a motor nerve terminal function at 4 h and 1, 3, 5 and 7 days after DFP injection. In untreated control animals 83% of alpha soleus motor axons generated post‐tetanic repetition (PTR) but after DFP the incidence of PTR was 40% at 4 h, 7% at 1 day, 8% at 3 days, 27% at 5 days and 72% at 7 days. Electron micrographs of neuromuscular junctions 3 days after DFP showed severe disruption of end‐plates and a conspicuous reduction in the number of motor nerve terminals. The remaining nerve terminals were retracted from the end‐plate region and were enveloped by Schwann cell processes. Internodal sprouting of soleus axons and post‐junctional alterations were still present at 7 days. The time course of the pre‐junctional defect coincided with, and contributed to, the reported post‐functional necrosis.