Reference

Effects of several aminopyridines and analogs on the calcium dependence of synaptic transmission

Effects of several aminopyridines and analogs on the calcium dependence of synaptic transmission. Matsumoto, Mitsuhiko; Riker, William K. (Sch. Med., Oregon Health Sci. 7680-59-3 and 13754-19-3 are also occured in this study. Univ., Portland, OR, USA). J. Pharmacol. Exp. Ther., 228(3), 573-8 (English) 1984. CODEN: JPETAB. ISSN: 0022-3565. DOCUMENT TYPE: Journal CA Section: 1 (Pharmacology) The effects of 4-aminopyridine (4-AP) [504-24-5], 4-aminopyridine methiodide (4-APMI) [7680-59-3], 3,4-diaminopyridine (3,4-DAP) [54-96-6], 4,5-diaminopyrimidine (4,5-DAPM) [13754-19-3] and 4-dimethylaminopyridine (4-DMAP) [1122-58-3] on synaptic transmission in isolated frog sympathetic ganglia were examd. In the absence of drugs, transmission failed progressively as Ca++ was reduced from 1.8 to 0.47 mM. However, the curve of the compd. action potential amplitude vs. log Ca++ was shifted to the left (lower Ca++) by all drugs in a dose-dependent fashion. The drugs varied in effectiveness in shifting the Ca++ dependence curve to the left, the order being: 3,4-DAP34-AP34,5-DAPM>4-APMI>4-DMAP. 4-AP, 3,4-DAP and 4,5-DAPM were also able to generate repetitive post-ganglionic discharge in response to a single orthodromic stimulus. All drugs, except 4,5-DAPM, were able to block synaptic transmission at higher concns., and their blocking potencies were in the following order: 4-DMAP34-APMI33,4-DAP34-AP. Thus, aminopyridines appear to preserve transmission in low Ca++ by facilitating Ca++ entry into presynaptic terminals, and the highest efficacy and potency are assocd. with unsubstituted amino groups and a nonquaternized pyridine N. .