簡要描述：VIP(Vasoactive Intestinal peptide) is a 28-amino acid peptide structurally related tosecretin. It was originally isolated from intestinal extracts and shown to be a potent vasodilator. Subsequent work demonstrated that VIP is very widely distributed in the peripheral and central nervous systems, and probably should not be considered a true GI hormone. A huge number of biological effects have been attributed to VIP. With respect to the digestive system, VIP seems to induce smooth muscle relax