A.N. Tupolev Kazan National Research Technical University 1 article published in JoVE Neuroscience Loading a Calcium Dye into Frog Nerve Endings Through the Nerve Stump: Calcium Transient Registration in the Frog Neuromuscular Junction Dmitry V. Samigullin1,2,3, Eduard F. Khaziev1,2,3, Nikita V. Zhilyakov1,2, Ellya A. Bukharaeva1,2, Eugeny E. Nikolsky1,2,4 1Laboratory of Biophysics of Synaptic Processes, Kazan Scientific Centre, Kazan Institute of Biochemistry and Biophysics, Russian Academy of Sciences, 2Open Laboratory of Neuropharmacology, Kazan Federal University, 3Department of Radiophotonics and Microwave Technologies, A.N. Tupolev Kazan National Research Technical University, 4Department of Medical and Biological Physics, Kazan State Medical University Here, we describe a method for loading a calcium-sensitive dye through the frog nerve stump into the nerve endings. We also present a protocol for the recording and analysis of fast calcium transients in the peripheral nerve endings.