Lower esophageal sphincter pressure (LESP) in man was measured by using a miniature semiconductor pressure sensor and the effects of clinical drugs on lower esophageal sphincter (LES) were examined. In total, 183 clinical cases were studied; 88 cases as controls, 38 esophagitis cases, 31 gastric ulcer cases, 21 duodenal ulcer cases, 4 liver cirrhosis cases and 1 scleroderma case. Drugs studied were pentagastrin, metoclopramide, domperidone, NaHCO₃, maalox, cimetidine, secretin, glucagon, nifedipine, and nicardipine hydrochloride. There results obtained were as follows.
Continuous intravenous drip infusion of pentagastrin (12μg/min) tentatively raises LESP. Also both metoclopramide and domperidone showed a tentative LESP-raising effect when administered either intravenously (10mg) or orally (10, 20mg) . The peak of the effect was 3-10 minutes after the intravenous injection and 20-30 minutes after the oral administration. The effect of oral administration lasted long and its effectiveness was as good as that of an intravenous injection. NaHCO₃ and maalox also raised LESP tentatively. The ordinary dose of NaHCO₃ (1.0g) or maalox (10ml) had the effect of raising LESP for approximately 30 minutes. LESP raising effect of intravenously injected cimetidine (200mg) was not clear. An intravenous injection of secretin (1u/kg) or glucagon (1.0mg) clearly lowered LESP. Also, orally administered nifedipine (10mg) or nicardipine hydrochloride (10mg) tentatively lowered LESP. LESP-lowering effect of nifedipine was tentatively inhibited by metoclopramide.