Table 2.

Choline desensitizes the tissue against acetylcholine

Conditions	Acetylcholine-induced increase in Isc		n
	Peak (ΔIsc; μEq/h per cm2)	Plateau (ΔIsc; μEq/h per cm2)
No choline	10.96 ± 0.97	3.13 ± 0.81	6
10−3 mol/L choline	6.68 ± 1.56*	0.58 ± 0.42*	6
No choline	9.88 ± 1.68	2.40 ± 0.97	6
5 × 10−4 mol/L choline	7.50 ± 1.39	2.34 ± 1.31	7
No choline	8.88 ± 1.73	1.47 ± 0.92	6
10−4 mol/L choline	10.34 ± 1.42	2.52 ± 0.80	6

Increase in I_sc evoked by acetylcholine (10⁻³ mol/L) across mucosa–submucosa preparations from rat distal colon under control conditions (“no choline”) or after pretreatment with three different concentrations of choline (administered three times in intervals of 15 min). Both the maximal increase in I_sc (peak) as well as the long-lasting rise in I_sc (measured 10 min after administration of acetylcholine) are given. Values are given as increase in I_sc above baseline just prior to administration of acetylcholine (ΔI_sc) and are means ± SEM.

^*P < 0.05 vs. response evoked by acetylcholine in the respective control series.