Electrical and mechanical stimulation of hair cells in the mudpuppy

• DOI: 10.1007/bf00657482
• Publication Date: 2004-11-27T12:38:08Z
• Authors: Olav Sand; Seiji Ozawa; Susumu Hagiwara
• Keywords: 0301 basic medicine; 03 medical and health sciences

1. The lateral line organ ofNecturus maculosus was stimulated with extracellular sine wave current, and the effect on the afferent activity was compared to the effect of mechanical vibration. Both mechanical and electrical stimulation caused phase locking between stimulus and afferent spikes (Figs. 2, 3). 2. Intracellular recordings were made from the three main cell types of the neuromast: hair cells, supporting cells and afferent nerve terminals. Mechanical stimulation evoked receptor potentials of less than 1 mV in the hair cells. These potentials were synchronized with the stimulus (Fig. 6E), and mechanical stimulation caused a corresponding synchronization of action potentials in the afferent nerve terminals (Fig. 6A). The supporting cells were insensitive to vibrations (Fig. 6C). 3. Intracellular injection of sine wave electrical current into hair cells caused synchrony between stimulus and afferent spikes (Fig. 6F), whereas even ten times more intense current was insufficient to cause such synchrony if the afferent nerve terminals were injected directly (Fig. 6B). Supporting cells were insensitive to electrical current stimulation (Fig. 6D). 4. The effective intracellular current injections in the hair cells caused membrane potential changes which overlapped in magnitude with the naturally occurring receptor potentials. The conclusion is therefore that the mechanically evoked receptor potentials in hair cells have a direct effect on the transmitter release, and the potentials are not an epiphenomenon caused by the secretory activity of the hair cells.