Table 2.

Ca²⁺ transients in subpopulations of medium-diameter DRG neurons

Subpopulation	n	Δ[Ca2+]i (nm)	T50 (s)
IB4+	96	331 ± 29**	8.9 ± 1.2**
IB4−	31	113 ± 11	3.5 ± 0.3
CAP+	85	319 ± 31**	8.2 ± 1.1
CAP−	42	166 ± 29	5.5 ± 1.5
IB4+/CAP+	65	344 ± 32	8.6 ± 1.3
IB4+/CAP−	31	271 ± 71	10.3 ± 4.1
IB4−/CAP+	20	115 ± 26	5.1 ± 1.1
IB4−/CAP−	11	113 ± 13	3.0 ± 0.2

The magnitude (Δ[Ca²⁺]_i) and decay (T₅₀) of high-K⁺-evoked Ca²⁺ transients were analysed in subpopulations of medium-diameter (i.e. 30–40 μm) DRG neurons. Subpopulations were defined by IB₄ binding, capsaicin (CAP) sensitivity or the combination of the two, and differences between groups (i.e. IB₄+versus IB_4–) were assessed. The magnitude was significantly larger

^**P < 0.01 and the decay of evoked Ca²⁺ transients was significantly (** P < 0.01) slower in IB₄+ neurons than in IB_4– neurons. The magnitude of the evoked Ca²⁺ transient was significantly (** P < 0.01) larger in CAP+ neurons than that in CAP– neurons. There was a significant (P < 0.01) group effect in the magnitude of evoked Ca²⁺ transients when subpopulations defined by the combination of IB₄ binding and CAP sensitivity were compared. Post hoc analysis (Tukey test) indicated that the magnitude of the transient in IB₄+/CAP+ neurons was significantly larger than that in IB_4–/CAP + (P < 0.05) and IB_4–/CAP– neurons (P < 0.01). There were no other significant differences between groups.