Abstract
Post-tetanic potentiation (PTP) of the fast excitatory postsynaptic potential (EPSP) in the curare-treated sympathetic ganglion of the bullfrog was inhibited by diazepam in a dose-dependent manner. Prostaglandins (PGs) of the E series (PGE1 and PGE2) mimicked the action of diazepam. Arachidonic acid, also inibited the PTP of EPSP. The inhibition obtained with diazepam could be potentiated in the presence of PGs or arachidonic acid. Pretreating the ganglion with 5,8,11,14-eicosatetraynoic acid, a prostaglandin synthetase blocker, abolished diazepam and arachidonic acid inhibition of PTP but not that of PGs. If the receptors for prostaglandins were blocked with a dibenzoxazepine derivative (SC 19220), the response to diazepam and arachidonic acid, as well as the PGs was abolished. None of these compounds inhibited the potential evoked by single shock. These data suggest that PGs may be involved in the action of diazepam in inhibiting the PTP. It is postulated that diazepam may increase the activity of PG synthetase that would result in the increased production of PGs, which may inhibit PTP of EPSP.
Footnotes
- Received October 27, 1973.
- Accepted February 8, 1974.
- © 1974 by The Williams & Wilkins Co.
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