The biophysical properties and distribution of voltage‐dependent, Ca²⁺ ‐modulated K⁺ (BK_Ca) currents among subpopulations of acutely dissociated DiI‐labeled cutaneous sensory neurons from the adult rat were characterized with whole‐cell patch‐clamp techniques. BK_Ca currents were isolated from total K⁺ current with iberiotoxin, charybdotoxin or paxilline. There was considerable variability in biophysical properties of BK_Ca currents. There was also variability in the distribution of BK_Ca current among subpopulations of cutaneous dorsal root ganglia (DRG) neurons. While present in each of the subpopulations defined by cell body size, IB4 binding or capsaicin sensitivity, BK_Ca current was present in the vast majority (> 90%) of small‐diameter IB4+ neurons, but was present in only a minority of neurons in subpopulations defined by other criteria (i.e. small‐diameter IB4−). Current‐clamp analysis indicated that in IB4+ neurons, BK_Ca currents contribute to the repolarization of the action potential and adaptation in response to sustained membrane depolarization, while playing little role in the determination of action potential threshold. Reverse transcriptase‐polymerase chain reaction analysis of mRNA collected from whole DRG revealed the presence of multiple splice variants of the BK_Ca channel α‐subunit, rslo and all four of the accessory β‐subunits, suggesting that heterogeneity in the biophysical and pharmacological properties of BK_Ca current in cutaneous neurons reflects, at least in part, the differential distribution of splice variants and/or β‐subunits. Because even a small decrease in BK_Ca current appears to have a dramatic influence on excitability, modulation of this current may contribute to sensitization of nociceptive afferents observed following tissue injury.

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