Fig. 1.

Low-dose mecamylamine fails to reduce chemoreceptor nerve response to hypoxia. A: polygraphic recording of experimental run. Top trace: chamber O₂ tension. Bar indicates period of mecamylamine perfusion. Bottom trace: raw recording of action potential (AP) activity recorded from petrosal chemoreceptor neuron with time on the abscissa and voltage on the ordinate. S1, S2, and S3 are stimulus artifacts during electrical stimulation to the carotid body for orthodromic AP initiation. B: frequency/Po₂ response relationship for chemoreceptor before (○), during (△), and following (■) perfusion with mecamylamine. Exponential line fits using least-squares method. Note increased response to hypoxia in presence of mecamylamine. C: expanded, overlaid traces during orthodromic stimulation from S1 to S3. In this case, mecamylamine slightly reduced AP height but did not change conduction time.