SENSORY ADAPTATION IN FROG VESTIBULAR ORGANS

Adaptation, i.e., the decrease with time in sensory units' afferent di scharge to a constant stimulus, appears to be a common feature of the receptors belonging to acoustico-lateralis system: However, the mechan isms underlaying this process are still a matter of debate. The presen t experiments demonstrate that sensory adaptation to both mechanical a nd electrical stimuli can be nearly suppressed after perilymphatic oua bain administration. This clearly indicates that the K+ homeostatic me chanisms [Valli et al., (1990) J. Physiol. (London) 430, 585-594] whic h control the K+ concentration gradient at both ends of vestibular hai r cells play a predominant role in this process. The possible importan ce of different K+-dependent mechanisms in hair cell adaptation is dis cussed.