Abstract
The actions of CaCl2, MgCl2, CdCl2, KCl, and veratrine on the asynchronous postganglionic firing which occurred following the injection of DFP into the arterial stream of the superior cervical ganglion of cats were studied. In addition, comparisons were made of the effects of these agents on the postganglionic responses evoked by supramaximal preganglionic volleys and injected ACh.
It was observed that CaCl2 blocked completely the DFP-discharge in doses which had no effect on the responses of the ganglia to threshold doses of ACh or preganglionic stimulation. On the other hand, the blockade of the DFP-discharge by MgCl2 was accompanied always by a depression of the other ganglionic responses studied. KCl evoked a postganglionic response which was superimposed upon the DFP-discharge. The blockade of the discharge by the prior administration of CaCl2 prevented also the response to KCl. However, the blockade of the discharge by a small dose of atropine had no effect on the response elicited by KCl.
Veratrine evoked a postganglionic discharge in the DFP-treated ganglia but not in the untreated ganglia. This action of veratrine was blocked by both CaCl2 and atropine. The increase following veratrine in the duration of the postganglionic action potentials was not affected by the doses of CaCl2 or atropine used in the present study.
(Ethylenedinitrilo) tetraacetic acid disodium (EDTA) evoked a postganglionic discharge in resting ganglia which was not blocked by atropine or hexamethonium. The calcium salt of EDTA produced no discernible change in the responses of the ganglia to preganglionic stimulation and did not evoke a postganglionic discharge.
Footnotes
- Received June 7, 1962.
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