Relative effects of dihydropyridine L-type calcium channel antagonism on biliary, duodenal, and vascular tissues: an in vivo and in vitro analysis in Australian brush-tailed possum

Medical treatment for sphincter of oddi dysfunction: Can it replace endoscopic sphincterotomy?

AIM: To report the results of a medical management of sphincter of oddi dysfunction (SOD) after an intermediate follow-up period.

METHODS: A total of 59 patients with SOD (2 men and 57 women, mean age 51 years old) were included in this prospective study. After medical treatment for one year, the patients were clinically re-evaluated after an average period of 30 mo.

RESULTS: The distribution of the patients according to the Milwaukee’s classification was the following: 11 patients were type 1, 34 were type 2 and 14 were type 3. Fourteen patients underwent an endoscopic sphincterotomy (ES) after one year of medical treatment. The median intermediate follow-up period was 29.8 ± 3 mo (3-72 mo). The initial effectiveness of the medical treatment was complete, partial and poor among 50.8%, 13.5% and 35%, respectively, of the patients. At the end of the follow-up period, 37 patients (62.7%) showed more than 50% improvement. The rate of improvement in patients who required ES was not significantly different compared with the patients treated conservatively (64.2% vs 62.2%, respectively).

CONCLUSION: Our study confirms that conservative medical treatment could be an alternative to endoscopic sphincterotomy because, after an intermediate follow-up period, the two treatments show the same success rates.

Effect of four medications associated with gastrointestinal motility on Oddi sphincter in the rabbit

AIM

Modulatory drugs of gastrointestinal (GI) motility are a possibility for use to relieve the main clinical presentation of sphincter of Oddi (SO) dysfunctions which are not easily distinguished from those occurring in high prevalence functional GI disorders. The aim of this study was to investigate the effects of GI motility modulators including pinaverium, domperidone, trimebutine, and tegaserod on the contractile activity of SO stimulated by carbachol in the rabbit.

METHODS

The contraction responses precontracted by carbachol (0.1 microM) of in vitro rabbit SO rings were evaluated before and after the addition of a series concentration (10(-13) to 10(-3)M) of pinaverium, domperidone, trimebutine, and tegaserod.

RESULTS

Pinaverium induced a concentration-dependent relaxation of isolated SO rings (10(-13) vs. 10(-7) vs. 10(-3)M = 16.6 +/- 4.8 vs. 47.1 +/- 5.5 vs. 81.2 +/- 6.2%, p < 0.001 by ANOVA) precontracted with carbachol (0.1 microM). Tegaserod did not significantly effect (10(-13) vs. 10(-7) vs. 10(-3)M = 2.3 +/- 2.2 vs. 6.7+/- 2.1 vs. 10.1 +/- 2.3%, p > 0.05 by ANOVA) SO motility, but domperidone seemed to stimulate SO contractions (10(-12) vs. 10(-7) vs. 10(-3)M = -2.2 +/- 1.5 vs. -13.9 +/- 2.0 vs. -21.0 +/- 2.7%, p < 0.05 by ANOVA). At low doses (10(-13) to 10(-7)M), trimebutine stimulated SO contraction (-8.7 +/- 1.4 vs. -9.3 +/- 2.0%); however, high doses (10(-6) to 10(-3)M) of trimebutine inhibited SO motility (-5.9 +/- 1.7 vs. 14.5 +/- 2.0%, p < 0.05 by ANOVA).

CONCLUSION

Pinaverium totally inhibits contractions induced by carbachol and tegaserod has no effect on carbachol-induced contractions. Domperidone stimulates contractions induced by carbachol. Trimebutine could either stimulate or inhibit SO contractions depending on its dosage.

Mechanisms of tension changes of the sphincter of Oddi from hypercholesterolemic rabbits

AIM: To observe the effects of hypercholesterolemia (HC) on tension of sphincter of Oddi (SO) in rabbits and to study the mechanisms of the sphincter of Oddi dysfunction (SOD).

METHODS: Twenty-four New Zealand female rabbits were divided randomly into control group and HC group (12 rabbits each). Sphincter of Oddi muscle rings were dissociated from both groups in vitro. Automatic contractility was observed firstly. Then the contraction responses evoked by KCl and CaCl₂ and relaxation responses caused by sodium nitroprusside (SNP) and nifedipine (Nif) were measured.

RESULTS: Compared with control group, the automatic contractile frequency of HC group was increased (P < 0.05), and the automatic contractile amplitude of HC group was decreased (P < 0.05). The tension of SO rings evoked by KCl at low and moderate concentrations (10-40 mmol/L) was significantly higher in HC group than in control group (P < 0.01). The maximum tension was not found difference between two groups, and both could be completely relaxed by Nif (3 mmol/L). Compared with the control group, relaxation responses of SO rings in HC group to SNP (0.1 nmoL/L-1 mmoL/L) were markedly decreased after the administration of KCl (60 mmoL/L) in HC group (P < 0.01). The minimum solution value (0.1 mmoL/L) of Ca²⁺ evoking contraction in HC group was evidently lower than that of the control group (1.0 mmoL/L) (P < 0.001). Tensions of SO rings evoked by Ca²⁺ (2.5 mmoL/L) were entirely relaxed by Nif (3 mmoL/L) both in HC group and control group. After the administration of KCl (60 mmoL/L) relaxation responses of rabbit SO rings to Nif (0.1 nmoL/L-3 mmoL/L) were not found difference between in the two groups. Nif (3 mmoL/L) could completely inhibit the contraction responses evoked by KCl or CaCl₂in both groups.

CONCLUSION: Hypercholesterolemia can lead to SO dysfunction and increase the sensitivity of SO to KCl at low and moderate concentrations in vitro. The overloading of intracellular Ca²⁺ is an important reason for these phenomena, which has no direct relation with L-type voltage-dependent calcium channels of smooth muscle cells.

Effects of bioactive agents on biliary motor function

Our understanding of biliary motility under normal and pathophysiologic conditions is still incomplete, but there have been recent advances. Of particular interest are the mechanisms involved in gallbladder filling and emptying, with a focus on understanding the processes underlying impaired gallbladder emptying leading to gallbladder dyskinesia and the formation of gallstones or cholecystitis. The sphincter of Oddi (SO) is a complex neuromuscular structure. Recent studies have attempted to unravel the specific neural or hormonal mechanisms operating under normal physiologic conditions and those that may lead to SO dysfunction. Furthermore, new research fronts are emerging, including the role of leptin in obese patients with impaired biliary motility and the action of electroacupuncture for possible treatment of SO dysfunction. This review illustrates the broad front of current research regarding the effects of bioactive agents on biliary motility, including enteric hormones, nitric oxide, opioids, inflammatory mediators, leptin, protease inhibitors, neurotransmitters, and electroacupuncture.

Sphincter of Oddi dysfunction: is there a role for medical therapy?

If the mechanism of pain in patients with sphincter of Oddi (SO) dysfunction is functional obstruction of the biliary tract, and at least in some patients it results from sphincter smooth muscle hypertrophy, then smooth muscle relaxants should have a theoretic role in the management of these patients. Calcium channel antagonists and other smooth muscle relaxants have been shown in "acute" manometric studies to alter SO motility. However, the effect of these agents on vascular smooth muscle remains a concern and often limits their use. At present the role of medical therapy is somewhat unclear because few well-conducted studies have used manometric criteria for the diagnosis of SO dysfunction and the selection of patients for therapy. The main drawback is that no drugs appear to be specific for the SO, long acting, and free of side effects.