Fig. 10.

The Na_V1.9 mRNA is selectively expressed in myenteric AH sensory neurons. A,Left panel, RT-PCR. cDNA isolated from rat DRG, guinea pig DRG, and guinea pig myenteric ganglia was amplified using primers to the gpNa_V1.9 gene (1.9). Amplified products were obtained from all cell types but not from negative controls containing no template (–). Right panel, Single-cell RT-PCR from a rat DRG neuron and from electrophysiologically identified guinea pig AH and S myenteric neurons. Two AH cells (AH₁,AH₂) and two S cells (S₁, and S₂) are shown. Note that amplified signals were obtained in AH cells but not in S cells. Positive control reactions were performed using specific primers to the α_osubunit of G-proteins, a ubiquitously expressed protein. These give a PCR product of 606 bp. Contamination from genomic DNA was routinely tested by omitting the reverse transcriptase in the templates. These controls were consistently negative in these experiments. AH neurons were identified by the sAHP currents characteristic of these cells (data not shown). M, One kilobase ladder DNA size standards. B, Current–voltage relationships obtained using slow voltage ramps (35 mV/sec) in the cells illustrated inA before single-cell RT-PCR. Note that only the AH cell displayed TTX-R I_Na. Leak currents measured in the –50 to –45 mV voltage range were subtracted.