title: Neuromuscular blocking effects of aminoglycoside antibiotics on fast- and slow-contracting muscles of the cat.
abstract: The neuromuscular-blocking effects of neomycin, streptomycin, and gentamicin were examined in fast- and slow-twitch muscles of pentobarbital-anesthetized cats. These antibiotics were more effective in reducing indirectly stimulated contractions of the gastrocnemius muscle than of the ipsilateral soleus muscle in adult cats. Respiratory-depressant effects of these antibiotics were more closely associated temporally with effects on soleus than on gastrocnemius twitch. Neomycin was a more potent neuromuscular blocking agent in kittens greater than 7 weeks old than in kittens less than 6 weeks old. Calcium ions were more effective in antagonizing the effects of neomycin on gastrocnemius than on soleus twitch; however, neostigmine was more effective in antagonizing the effects of neomycin on soleus than on gastrocnemius twitch. These data indicate a difference in responsiveness of fast- and slow-twitch muscles (fast greater than slow) to the neuromuscular-blocking effects of aminoglycoside antibiotics, and suggest that this may be related to a difference in the predominance of pre- and postjunctional inhibitory actions of these agents in the 2 muscle types.
mesh_terms: D000617:Aminoglycosides / Q000494:pharmacology*; D000771:Anesthesia, Intravenous; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002118:Calcium / Q000494:pharmacology; D002415:Cats; D055598:Chemical Phenomena; D002621:Chemistry; D004305:Dose-Response Relationship, Drug; D005260:Female; D005839:Gentamicins / Q000037:antagonists & inhibitors / Q000494:pharmacology; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009355:Neomycin / Q000037:antagonists & inhibitors / Q000494:pharmacology; D009388:Neostigmine / Q000494:pharmacology; D009466:Neuromuscular Blocking Agents; D013307:Streptomycin / Q000037:antagonists & inhibitors / Q000494:pharmacology; D013997:Time Factors
chemical_list: D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D005839:Gentamicins; D009466:Neuromuscular Blocking Agents; D009388:Neostigmine; D009355:Neomycin; D002118:Calcium; D013307:Streptomycin