[Slowly-adapting mechanoreceptor units of the guinea pig mammary nipple]

Slowly--adapting mechanoreceptor units of areola and nipple (MAI and MAII) at rest exhibited spontaneous 1--2/sec firing in 6% only. At constant mechanical displacement of the skin surface. MAI had an irregular firing while MAII--regular one. Mean frequency of MAI and MAII APs linearly depended on the amplitude of mechanical stimulus. trepeated stimulation of MAI and MAII reduced number of APs for each successive stimulus. At sinusoidal mechanical stimulation, the smallest AP threshold for MAI and MAII was about 10--15 Hz.