Frequency Of Phasic Contractions Research Articles

Sphincter of Oddi manometry before and after laparoscopic cholecystectomy.

In animal studies cholecystectomy has been found to alter the normal effect of cholecystokinin (CCK) on sphincter of Oddi (SO) function. This could be of importance with regard to the development of postcholecystectomy biliary pain. We therefore investigated the effect of laparoscopic cholecystectomy on SO motility before and after infusion with CCK. A prospective study of SO motility, under basal conditions and during CCK (ceruletide) infusion, was carried out in eight women with uncomplicated gallstone disease, before and after laparoscopic cholecystectomy. Laparoscopic cholecystectomy increased common bile duct pressure (P = 0.01) and decreased the frequency of phasic contractions (P=0.05). However, the inhibitory effect of CCK was preserved as infusion of CCK was associated with a significant reduction in SO phasic amplitude and frequency, both before and after cholecystectomy. Following laparoscopic cholecystectomy an indisputable inhibitory effect of CCK in the SO was found. Common bile duct pressure increased and minor modifications in basal SO motility were seen.

Effect of gastric distension on sphincter of Oddi motility in humans

Background~Aim: Although there are many reports in the literature of clinical syndromes resulting from sphincter of Oddi (SO) dysfunction, little is known about the effects of normal physiologic stimuli on SO function. The present study was designed to evaluate the effect of gastric distension on the SO motility through percutaneous transhepatic manometry. Methods: The motility of SO and small bowel(SB) were measured simultaneously by percutaneous transhepatic manometry using 8-lumen perfusion catheter (Zinetic Medical, 3 orifices for SO manometry: 2mm apart and 5 orifices for SB manometry: 10mm apart) in 6 patients(M:F=3:3, mean age: 67.5 years) with intrahepatic stones after complete stone removal by cholangioscopic lithotripsy. They had no previous hepatobiliary or gastrointestinal operation, papillary stenosis, and periampullary diverticulum. After positioning the catheter via PTBD tract, basal recording was performed. Gastric balloon was performed by ballooned nasogastric tube. The balloon was inflated on the regular contraction phase of SO until the patients felt epigastric discomfort. Result: The mean inflation volume of gastric balloon was 450ml (range: 300-700ml). At baseline manometric study, the basal pressure and amplitude and frequency of phasic contraction wave were 20.8 ± 2.3mmHg, 93.4 + 39.1mmHg, and 3.5 ± 1.3/min, respectively. After inflating the gastric balloon, the frequency of phasic contraction decreased to 0.8 + 1.2/min(p 0.05) and 36.6 ± 50.8mmHg(p>0.05), respectively. Conclusion: Gastric distension does not affect SO basal pressure and amplitude of phasic contraction wave, but decreases the contraction frequency of SO in humans.

TRH microinjection into DVC enhances motility of rabbits gallbladderviavagus nerve*

AIM:To investigate the effects of TRH in DVC on motility of the gallbladder in rabbits.METHODS:fter fasted for 15h-18h, rabbits were anesthetized with urethane (1.0g/kg).Gallbladder pressure (GP) was measured by a frog bladder perfused with normal saline.RESULTS:After microinjection of TRH (8.8nmol,1&mgr;l) into DVC,GP was raised and the frequency of phasic contraction of gallbladder (FPCGB) increased. All the doses of TRH (0.13, 0.25, 0.50, 0.80, 1.30nmol, 1&mgr;l) injected into DVC could excite the motility of gallblader. As the dose of TRH was enlarged, the amplitude and duration of the reaction increased. Effects of TRH in DVC on motility of the gallbladder could be completely abolished by atropine (0.2mg/g, i.v.) or vagotomy, but could not be inhibited by phentolamine iv (1.5mg/g) or propranolol iv (1.5mg/g)or by transecting the spinal cord.CONCLUSION: Thyrotropin-releasing hormone in DVC can excite motility of gallbladder. This effect was mediated by vagus nerves and peripheral M receptor. Its physiological significance may be related to maintaining the phasic contraction of gallbladder in interdigestive period.

Interstitial cells of Cajal as targets for pharmacological intervention in gastrointestinal motor disorders.

Interstitial cells of Cajal (ICCs) have recently been identified as the pacemaker cells for contractile activity of the gastrointestinal tract. These cells generate the electrical 'slow-wave' activity that determines the characteristic frequency of phasic contractions of the stomach, intestine and colon. Slow waves also determine the direction and velocity of propagation of peristaltic activity, in concert with the enteric nervous system. Characterization of receptors and ion channels in the ICC membrane is under way, and manipulation of slow-wave activity markedly alters movement of contents through the gut organs. Here Jan Huizinga, Lars Thuneberg, Jean-Marie Vanderwinden and Jüri Rumessen, suggest that, as ICCs are unique to the gut, they might be ideal targets for pharmacological intervention in gastrointestinal motility disorders, which are very common and costly.

The effect of Mn 2+, Zn 2+, Ba 2+ and Ca 2+ on spontaneous motility in sheep duodenum in vitro

1. 1. The effects of several ions, Mn 2+, Zn 2+, Ba 2+ and Ca 2+, on spontaneous motility were investigated in longitudinal smooth muscle strips from sheep duodenum, in vitro 2. 2. Mn 2+ (0.5–1.5 mM) and Zn 2+ (0.5–5 mM) inhibited both the amplitude and frequency of motility in Krebs solution and in Ca 2+-free medium. 3. 3. Ba 2+(0.5–5 mM) evoked three types of contractile responses: (i) an increase in the frequency and a reduction of the amplitude of spontaneous contractions; (ii) a slight increase in muscle tone of the phasic contractions; and (iii) a rapid initial phasic contraction followed by slowly fading contraction. Ca 2+ induced two kinds of responses in spontaneous motility: (i) a fast phasic contraction, followed by an increase in the amplitude and frequency of phasic contractions with no changes in its tone; and (ii) an increase in the amplitude of contractions. 4. 4. The Ba 2+-induced contractions were inhibited by EDTA, verapamil and diltiazem, but were not modified by sodium nitroprusside. The Ca 2+-induced contractions were reduced by verapamil and diltiazem. 5. 5. Our results show that Mn 2+ and Zn 2+ behave as inhibitors of sheep duodenum motility. In contrast, Ba 2+ and Ca 2+ stimulate motility. It is suggested that Ba 2+ can penetrate the cells through voltage-dependent Ca 2+ channels and behave as a partial substitute for Ca 2+.

Effect of propofol on human sphincter of Oddi.

The effect of propofol was studied in 11 patients who had common bile duct sphincter of Oddi manometry for suspected dysfunction. Patients were initially sedated with midazolam and then further or resedated with propofol for the second set of pressure measurements. Recordings were made about 10 min after giving each drug. No patient had elevated basal pressure initially. Average basal pressure was unchanged (16.7 +/- 16.4 mm Hg), phasic contraction frequency was unchanged (3.4 +/- 3.8/min), and phasic contraction amplitude fell but did not achieve statistical significance (91.8 +/- 77.3 mm Hg, P = 0.1). There was no difference in lowest blood pressure, pulse, or oxygen saturation recorded during midazolam or propofol sedation. Subjectively, the patients were more sedated during propofol administration. It is concluded that propofol is a safe and effective agent for conscious sedation. It does not alter the sphincter of Oddi pressure profile in patients with normal basal sphincter pressures and thus could be used as an alternative and perhaps better form of sedation for ERCP with sphincter of Oddi manometry.

Massive intestinal resection depresses circular smooth muscle contractility in the rat.

To determine whether functional changes in in vitro contractility and in vivo gastrointestinal transit accompany the adaptive structural changes seen in jejunal circular muscle after massive intestinal resection, rats were subjected to either surgical resection of 75% of the mid-jejunoileum or a sham operation. Basal stress in response to stretch was similar for both groups on postoperative days 10, 20, 30, and 40. By day 10 after surgery, tissues from resected rats exhibited a significant reduction in bethanechol-stimulated tonic stress and in frequency of phasic contractions. The amplitude of spontaneous phasic activity was significantly increased; however, following cholinergic stimulation, the magnitude of the increase in the amplitude of phasic activity was significantly reduced. Experiments with tetrodotoxin (10(-6) M) indicated a myogenic origin to the reduction in bethanechol-stimulated tonic stress and the reduced frequency and altered amplitude of phasic contractile activity in resected animals. The tonic stress developed in response to depolarization with KCl did not differ significantly between sham-operated and resected rats. Transit studies showed no change in the rate of gastric emptying after resection but did reveal a significant reduction in the velocity of intestinal transit. Thus, following massive intestinal resection the bethanechol-stimulated tonic stress response and phasic contractile activity of circular smooth muscle are significantly reduced, concomitant with altered intestinal transit. The reduction in contractility in the resected animals may be due to an alteration at the level of the smooth muscle receptor and (or) its signal transduction pathway.

Effect of gastrectomy on gallbladder motility: an experimental study

Gallstone formation is frequently seen following gastric surgery. Since dysmotility and bile stasis of the gallbladder is considered as an important factor in the pathogenesis of gallstone formation, altered gallbladder motility due to gastric surgery may have a role in the development of post-gastrectomy gallstone formation. To test this hypothesis, the effect of distal partial gastrectomy on gallbladder motility were studied. Gastroduodenal and gallbladder contractions were recorded by chronically implanted strain gauge transducers under conscious state. Gallbladder volume changes were monitored using chronically indwelling gallbladder catheter. Fasted and fed motility were studied in control (n = 5) and gastrectomized (n = 3) dogs. Plasma concentration of putative hormone CCK was measured. Effect of CCK-OP and motilin on gallbladder emptying were also studied. In fasted state, gallbladder volume was periodically decreased synchronous with phase 3 of interdigestive migrating contractions (IMC) in the gastroduodenum in both group of dogs. The correlation between gastric and gallbladder contractions was preserved even following distal partial gastrectomy, though the frequency of phasic contractions during phase 3 of IMC was decreased in the gastrectomized dogs. Postprandial gallbladder emptying tend to decreased in the gastrectomized dogs, while there were no difference in the postprandial plasma CCK concentrations and CCK-OP induced gallbladder emptying between groups. Digestive period was shortened in the gastrectomized dogs, which resulted in early gallbladder refilling and prolonged interdigestive period. Decreased frequency of gallbladder phasic contractions during IMC and prolonged interdigestive period could cause bile stasis in the gallbladder, which may, in part, explain post-gastrectomy gallbladder formation.

Effects of gastrectomy on motility, perfusion pressure, and caerulein-induced relaxation of sphincter of Oddi in dogs.

The effects of subtotal-gastrectomy (gastrectomy) on the spontaneous motility and caerulein-induced relaxation of the sphincter of Oddi (SO) were investigated in the dog. The spontaneous motility and the response to caerulein of the SO were recorded using perfusion method. The basal perfusion pressure (5.1 +/- 0.5 cmH2O) and the frequency of phasic contractions (6.1 +/- 0.5 cycles/min, c/min) of the SO increased to 8.2 +/- 0.6 cmH2O (p < 0.05) and 9.3 +/- 0.4c/min (p < 0.05) after gastrectomy, respectively. They were observed one month after operation (7.8 +/- 0.5 cmH2O and 9.1 +/- 0.9 c/min, p < 0.05), but did not change by vagotomy with sympathectomy (vagosympathectomy). In the spontaneous motility of the SO, the motility index increased to 143.7 +/- 18.7% (p < 0.05) at 4 hrs and 135.0 +/- 9.1% (p < 0.05) at one month after gastrectomy, but did not increase after vagosympathectomy. Caerulein had an inhibitory effect on the SO motility in the normal animal 48.0 +/- 4.2%). Gastrectomy reversed to the excitatory effect from the inhibitory effect to caerulein at 4 hrs (127.6 +/- 5.3%, p < 0.05) and at one month (126.6 +/- 5.3%, p < 0.05) after operation, but not reversed by vagosympathectomy and sham gastrectomy. The excitatory response to caerulein after gastrectomy was not effected by vagosympathectomy. It is concluded that gastrectomy induced the SO dysfunction, an increase of the perfusion pressure and the frequency of phasic contractions of the SO, and a change of the response to caerulein of the SO. These alterations suggests that one of the mechanisms of the regulation of the SO motility exist as the reflex from the stomach and/or uppermost duodenum through intrinsic nervous pathways.

Meperidine need not be proscribed during sphincter of Oddi manometry

Meperidine is routinely proscribed during sphincter of Oddi manometry because narcotics have been associated with spasm of the sphincter of Oddi. We have performed a prospective study of the effect of meperidine on sphincter of Oddi manometry in 18 patients undergoing manometry for suspected sphincter dysfunction. After diagnostic manometry using only intravenous diazepam sedation, the endoscope remained in the duodenum while 1 mg/kg intravenous meperidine was given. Five minutes later sphincter manometry was repeated. There was no difference in the baseline sphincter pressure before and after meperidine in all patients. The frequency of phasic contractions increased after meperidine ( p = 0.001). Baseline sphincter pressure is generally the only manometric criteria used to diagnose sphincter dysfunction and this did not change after meperidine. We conclude that meperidine may be used for additional analgesia during sphincter manometry. This may improve patient tolerance and the success rate of this procedure. (Gastrointest Endosc 1994;40:7-9.)

The association of proctolin with the spermatheca of the locust, Locusta migratoria

The association of proctolin or a proctolin-like peptide with the spermatheca of Locusta migratoria has been shown using immunohistochemistry and RP-HPLC coupled to the sensitive locust oviduct bioassay. Immunohistochemistry reveals that a proctolin-like peptide is present in processes and terminal arborizations on the spermatheca, in axons of the nerves which project to the spermatheca and in neurons in the eighth abdominal ganglion. The spermatheca of Locusta is sensitive to proctolin, with exposure to proctolin resulting in dose-dependent increases in muscle tonus as well as increases in amplitude and frequency of phasic contractions. The threshold for proctolin's effect is approximately 10 −9 M with a maximum at approximately 5 × 10 −8 M. The effects of proctolin on contractions of the spermatheca are reversible. The results indicate that proctolin, or a very similar peptide, is associated with the spermatheca of the locust Locusta migratoria and may play a neural role in modulating muscular activity.

Human sphincter of Oddi motility and cholecystokinin response following liver transplantation.

The reported incidence of sphincter of Oddi dysfunction following orthotopic liver transplantation has ranged from 3% to 7%. If sphincteric dysfunction is unrecognized, therapy may be inappropriate; when recognized, extensive surgery may be required. To prospectively identify patients with sphincteric dysfunction, we performed sphincter of Oddi motility studies through the t-tube tract three months after transplantation. Baseline sphincter motility and response to intravenous cholecystokinin were evaluated. The results of 10 subjects are reported; nine had normal basal sphincter pressure (16 +/- 5.8 mm Hg), and all had normal frequency (3.6 +/- 1/min), amplitude (86 +/- 31 mm Hg), and duration (4.5 +/- 1 sec) of phasic contractions. One subject had an elevated basal pressure (47 mm Hg). All, including the subject with elevated basal pressure, demonstrated a normal response to intravenous cholecystokinin with significant inhibition of phasic contraction frequency and amplitude. We demonstrate that simultaneous studies of the sphincter and duodenum can be obtained via the t-tube tract, providing the opportunity for prospective evaluation of sphincteric function. We conclude that sphincter of Oddi function usually remains normal following liver transplantation with choledochocholedochostomy.

Erythromycin and motilin stimulate sphincter of Oddi motility and inhibit trans-sphincteric flow in the Australian possum.

The actions of erythromycin lactobionate and porcine motilin on trans-sphincteric flow and simultaneous sphincter of Oddi motility were studied in 15 anaesthetized Australian Brush-tailed possums (Trichosurus vulpecula). Erythromycin (25-200 micrograms/kg) and motilin (25-200 ng/kg) were administered as graded doses by close intraarterial injection. Trans-sphincteric flow was measured as inflow and outflow. Both motilin and erythromycin decreased trans-sphincteric inflow (both P < 0.0001) and outflow (P < 0.0001 and P = 0.0017 respectively) in a dose-dependent manner. The highest dose of each agent abolished trans-sphincteric flow. These agents increased sphincter of Oddi phasic contraction frequency and basal pressure up to 2 and 3 fold respectively (P < 0.05). The amplitude of the sphincter of Oddi phasic contractions were not influenced in any consistent fashion by either agent. The durations of the responses (trans-sphincteric inflow) elicited by erythromycin and motilin were dose dependent (P = 0.0225 and P = 0.0001 respectively). The actions of erythromycin (200 micrograms/kg) or motilin (100 ng/kg) on trans-sphincteric flow and sphincter of Oddi motility were not influenced by neural blockade with tetrodotoxin. These findings support the hypothesis that erythromycin acts as a motilin agonist and both substances increase the resistance to flow through the sphincter of Oddi by raising the basal pressure and frequency of contractions.

Sphincter of Oddi dysfunction and unexplained abdominal pain: Clinical and manometric study

Unexplained, biliary-type abdominal pain is often attributed to an abnormal pressure profile of the sphincter of Oddi. In spite of this assumption, the true prevalence of this type of motor dysfunction among cholecystectomized patients with unexplained abdominal pain is not known. We studied 64 postcholecystectomy patients who were thought to have sphincter of Oddi dysfunction. Radiologically, other than a dilated common bile duct in some, they had no anatomic derangement of their pancreatobiliary tract to explain their symptoms. They were categorized into three groups on the basis of four objective findings suggesting abnormal biliary emptying mechanism. Basal sphincter of Oddi pressure, frequency of phasic contractions, and proportion of retrograde contractions were determined in all patients. Twenty-six (41%) of the patients demonstrated at least one motor abnormality, 16 (25%) had two, and 10 (16%) had all three abnormal parameters. The pressure profile of the sphincter was normal in 38 or 59% of the patients. Seventy-three percent (73%) of the patients in group I, who had three or four of the objective findings for sphincter of Oddi dysfunction, demonstrated at least one motor abnormality. Sixty percent of this group demonstrated an increased basal sphincter of Oddi pressure. On the other hand, only 19% of the patients in group III, who had none of the objective findings, revealed a motor abnormality. Increased basal sphincter of Oddi pressure was noted in 7% of this group. We conclude that, sphincter of Oddi dysfunction, as diagnosed manometrically, explains the recurrent biliary type abdominal pain in a minority of patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Location of enkephalinase and functional effects of [Leu5]enkephalin and inhibition of enkephalinase in the feline main pancreatic and bile duct sphincters.

1. Morphological studies have demonstrated enkephalinergic nerve fibres in proximity to the sphincter of Oddi, and opiates are known to contract this sphincter. In this study, the flow resistances in the common bile duct and main pancreatic duct sphincters were studied simultaneously in anaesthetized cats using a perfusion technique. 2. Naloxone did not affect the activity of these sphincters under basal conditions, indicating that there is no basal enkephalinergic tone. 3. The response to [Leu5]enkephalin (0.015-15 micrograms/kg), morphine (1 mg/kg) and ketamine (10 mg/kg) was a naloxone-sensitive increased activity in the sphincters with a raised frequency of phasic contractions. The threshold dose for an effect of [Leu5]enkephalin on the sphincter of Oddi was 0.015 microgram/kg and a maximal response was observed at 0.75 microgram/kg. There were no differences in the response of the main pancreatic duct sphincter and the bile duct sphincter to the different drugs. 4. Immunoautoradiographic studies demonstrated enkephalinase in the sphincter++ of Oddi. 5. Acetorphan (3 mg/kg intravenously), which inhibits endogenous enkephalinase both in the peripheral and the central nervous system when administered parenterally, caused a naloxone-sensitive contraction, whereas thiorphan (3-20 mg/kg), an enkephalinase inhibitor that does not easily penetrate the blood-brain barrier, had no effect on the sphincter of Oddi. 6. These results show that endogenous and exogenous opiates influence the function of the feline sphincter of Oddi and that enkephalins may be involved in the physiological control of this sphincter, although not under basal conditions.

Effect of local instillation of alcohol on sphincter of Oddi motor activity: combined ERCP and manometry study

The effect of local instillation of alcohol on sphincter of Oddi motor activity was determined by endoscopic manometry. Sphincter of Oddi pressures and motor function were compared in eight cholecystectomized subjects with normal sphincter of Oddi motor function and in four patients with chronic alcoholic pancreatitis. The effect of local instillation of 3 ml of 40% alcohol was compared with water instillation. In cholecystectomized subjects, alcohol produced a significant increase of basal sphincter of Oddi pressure from 21.0 +/- 2.8 mm Hg to 95.8 +/- 83 mm Hg (p less than 0.01) without significant changes in the amplitude, duration, and frequency of phasic contractions. In patients with alcoholic chronic pancreatitis, alcohol instillation resulted in a significant increase of basal sphincter of Oddi pressure from 32.5 +/- 4.8 mm Hg to 225.1 +/- 105 mm Hg without changes in amplitude, duration, and frequency of phasic contractions. Two patients with chronic alcoholic pancreatitis had a tonic contraction of the sphincter of Oddi with transitory and mild epigastric pain. Local instillation of alcohol increases sphincter of Oddi motor activity which may play a role in the pathogenesis of alcoholic pancreatitis.

The hindgut muscularis of the stable fly, Stomoxys calcitrans: Some of its structural, motile and pharmacological properties

The muscles of the hindgut of the stable fly, Stomoxys calcitrans L., are arranged in a fine regular lattice of longitudinal and circular fibres with diameters that range between 7 and 16 μm. The hindgut is innervated by a proctodeal nerve that branches and projects along the rectum and colon. Four distinct patterns of motile activity were evident in the hindgut; compression, peristalsis, reverse peristalsis and segmentation. Compressions that were recorded myographically showed distinctive activity patterns. When the proctodeal nerve was stimulated by a single electrical pulse, the longitudinal muscles of the hindgut responded with a single monophasic contraction that lasted 800 ms. If the frequency of the stimulating pulse was increased, individual responses could be distinguished until the stimulus reached 10 pulses/s. At this point, a complete fusion of contractile events occurred and the amplitude doubled. The hindgut showed a sensitivity to l-glutamate in micromolar amounts with a threshold for increasing the frequency of phasic contractions at a concentration of 10 −5 M. At 10 −4 M, glutamate and above tonic changes were evident. The threshold concentration for hindgut excitation with proctolin fell between 10 −15 and 10 −10 M. At these levels, increases in the amplitude and frequency of phasic contractions were generally evident. At a proctolin concentration of 10 −9 M and above, tonic changes were observed. Evidence for proctolin desensitization of the stable fly hindgut is discussed. Although 80% of the stable fly preparations tested were unresponsive to leucomyosuppressin, 20% did whow a weak inhibitory reaction.

Galanin: Distribution and Effect on Contractile Activity and Release of Vasoactive Intestinal Polypeptide from the Isolated Perfused Porcine Ileum

In the pig ileum galanin (GAL)-like immunoreactivity was identified in nerve cell bodies of the submucous plexus and in nerve fibers of the circular and longitudinal muscle layer. Infusion of 5.10(-10)-10(-8) M of GAL into the arterial line of the isolated perfused porcine ileum decreased the frequency of spontaneous phasic contractions in a dose-dependent manner. The frequency of phasic contractions during maximal inhibition by GAL 10(-8) M was 13 +/- 4% (mean +/- SE) of basal frequency (p less than 0.05). The recovery from inhibition by GAL 10(-8) M lasted 16 +/- 1 min. Tonic contractions were not observed in this experimental set-up, neither by standard perfused catheter manometry nor by measurement of cross-sectional area of an intraluminally located balloon. Infusion of GAL 10(-8) M decreased the venous release of vasoactive intestinal polypeptide to 80 +/- 8% of basal release (p less than 0.05). It is concluded that GAL may participate in the regulation of small intestinal motility in the pig.

The presence of proctolin in the reproductive system of Rhodnius prolixus

The distribution of proctolin throughout the reproductive system of female Rhodnius prolixus has been studied using reversed-phase high-performance liquid chromatography (RP-HPLC) together with a sensitive bioassay for proctolin. The spermathecae contained the largest amount of proctolin per mg protein, followed by the common oviduct, the bursa and lateral oviducts, with the ovaries containing the lowest amount. Immunohistochemistry of the reproductive structures revealed proctolin-like immunoreactivity in terminal aborisations extending from the lateral oviducts across the common oviduct, spermathecae and along to the bursa. No immunostaining was evident on the ovaries or cement gland. The oviducts of Rhodnius are sensitive to proctolin, with exposure to proctolin producing a dose-dependent increase in muscle tonus as well as an increase in amplitude and frequency of phasic contractions. Proctolin also produces an increase in the frequency of the rhythmical contractions of the spermathecae. The results indicate that proctolin is probably involved in the regulation of events associated with reproduction in this hemipteran.

Effect of nifedipine on sphincter of Oddi motor activity: Studies in healthy volunteers and patients with biliary dyskinesia

The effect of nifedipine on sphincter of Oddi (SO) motor activity was determined by endoscopic manometry. Sphincter of Oddi pressures and motor function were compared in 21 healthy volunteers and in 9 patients with SO dyskinesia. The effects of sublingual doses of 10 or 20 mg of nifedipine were compared with placebo. Neither placebo nor 10 mg of nifedipine produced any effect on SO motor activity. In healthy volunteers 20 mg of nifedipine produced a moderate but significant decrease in basal SO pressure from 12.0 to 6.7 mmHg as well as in the amplitude, duration, and frequency of phasic contractions. In patients with SO dyskinesia 20 mg of nifedipine also resulted in a significant but more profound decrease of the basal SO pressure from 47.1 to 17.3 mmHg as well as in a decrease of amplitude, duration, and frequency of the phasic contractions. Neither placebo nor 10 or 20 mg of nifedipine has any effect on the sequence of phasic contractions. In summary, nifedipine may have a possible therapeutic role in the treatment of SO dyskinesia.