Intensity and frequency characteristics of pacinian corpuscles. III. Effects of tetrodotoxin on transduction process

This is the third in a series of three papers dealing with intensity and frequency characteristics obtained on pacinian corpuscles isolated from the cat mesentery (8, 9). The experimental results show that tetrodotoxin (TTX) affects not only regenerative action potentials but also the measured receptor (generator) potentials. Extracellularly recorded receptor and action potentials were simultaneously recorded in response to sinusoidal displacement stimuli. Receptor potentials measured in this manner responded with a time course similar to the driving frequency. Since the duration of the action potentials is long relative to the cycle period at high stimulus frequencies, the underlying receptor potentials can become obscured. To prevent this, TTX was applied through superfusion at a concentration of 6.0 microM. After about 30 min, the neural spikes were fully eliminated but the receptor potentials were also decreased in amplitude. Intensity characteristics relating receptor-potential amplitudes to probe displacement amplitudes showed that the percentage decrease in amplitude due to the application of TTX was constant regardless of stimulus intensity. Frequency characteristics relating probe displacement amplitudes to vibration frequency for a constant-response criterion showed an increase in the displacement amplitude required for the criterion response, across frequency, when TTX was applied. On average, the increase was a power function of vibration frequency.(ABSTRACT TRUNCATED AT 250 WORDS)