[The effect of 4-aminopyridine on indirectly evoked contractions of the diaphragm in rats in situ].
The aim of the present study was to investigate the influence of three doses of 4-aminopyridine (1, 3 and 10 mg/kg i.v.) on the amplitude of contraction of rat diaphragm indirectly stimulated by electrical impulses of various frequencies (0.1, 1, 10, 50 and 100 Hz). All the doses used significantly augmented the post-tetanic single twitch potentiation after stimulation with 100 Hz (by 35-40%). Doses of 3 and 10 mg/kg i.v. of 4-aminopyridine significantly increased the contractile response to the 10 Hz stimulation (by 73-77%), while only 3 mg/kg i.v. significantly (by 35-39%) increased the amplitude of initial single twitches. It is concluded that the 4-aminopyridine-induced blockade of presynaptic potassium channels caused potentiation of the indirectly evoked contractions of rat diaphragm in situ, which is both dose- and frequency-dependent.
Ivković-Lanier
B
B
Vojnotehnicki institut, Odeljenje za medicinsku zastitu, Beograd.
Stojiljković
M P
MP
D015761:4-Aminopyridine / Q000494:pharmacology*; D000818:Animals; D003964:Diaphragm / Q000187:drug effects* / Q000502:physiology; D004558:Electric Stimulation; D009119:Muscle Contraction / Q000187:drug effects*; D015221:Potassium Channels / Q000187:drug effects; D051381:Rats
D015221:Potassium Channels; D015761:4-Aminopyridine