Sphingosine 1-Phosphate Enhances Spontaneous Transmitter Release at the Frog Neuromuscular Junction
Document Type
Article
Publication Date
1-1-2002
Description
Intracellular recordings were made from isolated frog sciatic-sartorius nerve-muscle preparations, and the effects of sphingosine 1-phosphate (S1-P) on miniature endplate potentials (MEPPs) were studied. Extracellular application of S1-P (1 and 30 μM) had no significant effects on the frequency and amplitude of MEPPs. Delivery into nerve terminals by liposomes containing 10-5, 10-4 or 10-3 M S1-P was associated with a concentration-dependent increase in MEPP frequency of 37, 63 and 86%. The per cent of median MEPP amplitude was not significantly changed, but there was an increase in the number of 'giant' MEPPs. Pre-exposure of the preparations to S1-P 10-5 but not 10-8 M entrapped in liposomes for 15 min blocked the effects of subsequent superfusion of S1-P (10-4 M)-filled liposomes on MEPP frequency. Thus, intracellular S1-P receptors seem to undergo 'desensitization' to higher concentrations of S1-P. The result provides the first evidence that S1-P acting intracellularly but not extracellularly enhances spontaneous transmitter release at the frog neuromuscular junction.
Citation Information
Brailoiu, Eugen; Cooper, Robin L.; and Dun, Nae J.. 2002. Sphingosine 1-Phosphate Enhances Spontaneous Transmitter Release at the Frog Neuromuscular Junction. British Journal of Pharmacology. Vol.136(8). 1093-1097. https://doi.org/10.1038/sj.bjp.0704839 PMID: 12163341 ISSN: 0007-1188