“…Magnesium sulphate has previously been shown to cause an increase in colonic motor activity (Davidson, Sleisenger, Almy, and Levine, 1956), but it is difficult to be certain about its mechanism of action. It is a powerful stimulus for the release of cholecystokinin from small intestinal mucosa, as was originally shown indirectly by studies of gallbladder contraction (Lyon, 1919;Boyden and Birch, 1930;Boyden et al, 1943) and more recently confirmed by direct radioimmunoassay measurement of serum levels of cholecystokinin in normal subjects after oral MgSO4 Harvey, Grayburn, Jennings, and Hartog, 1974). Injection of this hormone results in an increase in both small intestinal (Adlercreutz, Pettersson, Adlercreutz, Gribbe, and Wegelius, 1960;Dahlgren, 1966;Parker and Bene-ventano, 1970) and colonic (Grossi et al, 1966;Dinoso et al, 1972;) motor activity.…”