Diffusion coefficient of AcCho [acetylcholine] in synaptic cleft

Value 400 µm^2/sec
Organism Lizard Anolis carolinensis
Reference Land BR, Harris WV, Salpeter EE, Salpeter MM. Diffusion and binding constants for acetylcholine derived from the falling phase of miniature endplate currents. Proc Natl Acad Sci U S A. 1984 Mar81(5):1594-8. abstractPubMed ID6584895
Method "[Researchers] recorded MEPCs [miniature endplate currents] by voltage clamp from the intercostal muscle of the lizard Anolis carolinensis, using experimental techniques as in the first two papers of this series (1, 2) with minor modifications."
Comments "[Researchers] find diffusion to be 4×10^-6cm^2/sec, slightly slower than free diffusion, forward binding to be 3.3×10^7M^-1 s^-1, and the distance from an average release site to the nearest exit from the cleft to be 1.6µm...The diffusion rate constant is somewhat smaller than that for free diffusion [given as 6-10×10^-6cm^2/Sec (refs 28-30)]."
Entered by Uri M
ID 111076