A Method for Differential Measurement of Free and Bound Acetylcholine in the Small Intestine

It is well known that almost all acetylcholine (ACh) in tissues is present in a bound form and is released during excitation. In order to study the physiological role of ACh, the free form should be distinguishable from that of the bound. In previous papers (1-4) the amount of ACh diffused into the bathing solution of the intestine was considered to exhibit the entire amount of ACh released from tissue, however, there remains the possibility of retainment. Extraction of free ACh would be more satisfactory if the tissue were sliced before extraction. In this report, an attempt has been made to determine a method which would demonstrate the total picture of the tissue bound and free ACh in one operation.