Dependence on temperature of the effect of dinitrophenol on the release of transmitter quanta at neuromuscular junctions in the mouse diaphragm.
1. The frequencies (F, s-1) of miniature endplate potentials and the quantal content (m) of endplate potentials were measured intracellularly and simultaneously at mouse diaphragm endplates in a bathing solution that contained 0.6 mM Ca2+ ions and 5 mM Mg2+ ions. 2. Twin pulses at 4 ms intervals gave the quantal contents of the first (m1) and second (m2) responses. The ratio of m2/m1 was taken as an indicator of the temporal facilitation of the release of transmitter. 3. Dinitrophenol (DNP, 10 microM) increased the values of F and m at 36 degrees C. This effect did not depend on extracellular Ca2+ ions. 4. The potentiating effect of DNP disappeared at 24 degrees C but the value of m2/m1 remained constant. 5. These results suggest that the effect of DNP is modifiable by temperature which can affect systems that control the intracellular metabolism of Ca2+ ions.
Nishimura
M
M
Department of Pharmacology, University of Obihiro School of Veterinary Medicine, Japan.
Taquahashi
Y
Y
Fujita
K
K
Satoh
E
E
Shimizu
Y
Y
D000818:Animals; D002118:Calcium / Q000378:metabolism; D003964:Diaphragm / Q000187:drug effects / Q000378:metabolism; D004140:Dinitrophenols / Q000494:pharmacology*; D004558:Electric Stimulation; D005071:Evoked Potentials / Q000187:drug effects; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D009045:Motor Endplate / Q000187:drug effects / Q000378:metabolism; D009411:Nerve Endings / Q000187:drug effects / Q000378:metabolism; D009469:Neuromuscular Junction / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D018377:Neurotransmitter Agents / Q000378:metabolism*; D010791:Phrenic Nerve / Q000187:drug effects; D013696:Temperature; D014475:Uncoupling Agents / Q000494:pharmacology*
D004140:Dinitrophenols; D018377:Neurotransmitter Agents; D014475:Uncoupling Agents; D002118:Calcium