Nitric oxide and gall-bladder motor function

Probable Rare Case of Cholecystitis After Exposure to Supratherapeutic Doses of Hydralazine

Objective: To report a rare case of cholecystitis in a patient who received supratherapeutic doses of hydralazine for 1 month. Case Summary: A 79-year-old woman was admitted with severe right upper quadrant abdominal pain. Three weeks prior, she suffered a similar episode and was told she had a buildup of sludge in her gall bladder. For the past month, she had inadvertently received 400 mg of hydralazine per day instead of 150 mg; she was also prescribed fenofibrate 145 mg daily. Her workup was remarkable only for a slightly elevated white blood cell count and gall bladder sludge and distention without common duct obstruction. She was diagnosed with cholecystitis and underwent a laporoscopic cholecystectomy within 72 hours of admission. She was subsequently discharged a day later with the corrected hydralazine dose, and she has not been readmitted to the hospital. Discussion: Hydralazine is a direct acting vasodilator that may also potentiate the effects of nitric oxide. Nitric oxide has been linked to decreased gall bladder motility in in vivo and in vitro studies. The Naranjo algorithm indicates that this is a probable adverse event of fenofibrate and of hydralazine; the Drug Interaction Probability Scale indicates that this case of cholecystitis was a possible result of the interaction between hydralazine and fenofibrate. Based on the time course of the patient’s medication use and symptoms, hydralazine is more likely to be the cause of her cholecystitis than her other medications. Conclusion: Clinicians should be aware that high doses of hydralazine may inhibit gall bladder motility and contribute to the buildup of bile sludge.

Gallstone disease: Primary and secondary prevention

Several risk factors for cholesterol gallstone formation in the general population have been identified. There is a strongly increased risk of gallstone disease during prolonged fasting, rapid weight loss, total parenteral nutrition, and somatostatin(-analogue) treatment. The annual risk of biliary colic and gallstone complications in asymptomatic gallstone carriers has been investigated sparsely. In asymptomatic and symptomatic gallstone carriers, treatment with the hydrophilic bile salt ursodeoxycholic acid (UDCA) has been claimed to reduce the risk of biliary colic and gallstone complications such as acute cholecystitis and acute pancreatitis. Also, prophylactic cholecystectomy could be beneficial in certain subgroups of asymptomatic gallstone carriers. However, randomized, double-blind, placebo-controlled trials are lacking. In this review, strategies for the prevention of gallstone formation in the general population and in high-risk conditions are dealt with. Also, strategies for the prevention of biliary colic and gallstone complications in asymptomatic and symptomatic gallstone carriers are discussed.

Correlated expression of inducible nitric oxide synthase and P53, Bax in benign and malignant diseased gallbladder

Our goal has been to investigate the expression and correlated significance of inducible nitric oxide synthase (iNOS) and P53, Bax in benign and malignant gallbladder diseases. We detected the expression of iNOS, P53 and Bax in the gallbladder wall by SP immunohistochemistry in 16 cases of chronic cholecystitis, 11 cases of chronic cholecystitis with adenomyoma and 24 cases of gallbladder adenocarcinoma. The percentage of positively marked tumor cells was counted under microscope and the intensity of immunoreactivity was graded. SPSS10.0 statistical software was applied for statistical analysis. In this study, we found that: (1) Both benign and malignant diseased gallbladder wall expressed iNOS and Bax. Compared to benign diseased gallbladders, their expression in adenocarcinoma was decreased (p < 0.05), P53 was expressed strongly only in nuclei of adenocarcinoma cells of some cases. (2) In benign and malignant diseased gallbladders, iNOS expression was related positively to Bax (p < 0.01), the expression of P53 and Bax had a negative relationship (p < 0.01). The results suggested that both chronic cholecystitis and chronic cholecystitis with adenomyoma carry the risk of becoming malignant, especially the latter. NO is an important mediated molecule in cancer, there are intimate relationships between gallbladder cancer and apoptosis.

Relaxation of canine gallbladder to nerve stimulation involves adrenergic and non-adrenergic non-cholinergic mechanisms

Electrical field stimulation (EFS) of dog gallbladder strips induced a frequency-dependent contractile response followed by an off-relaxation that was turned into a pure inhibitory response after atropine pretreatment. Guanethidine reduced the atropine-induced relaxing responses, so an adrenergic mechanism can partially account for the nerve-mediated gallbladder relaxation. However, guanethidine pretreatment also revealed a nonadrenergic noncholinergic (NANC) relaxation induced by EFS, which was frequency independent. NANC relaxations were reduced by L-arginine methyl ester (L-NAME, 100 micromol L-1), a nitric oxide synthase inhibitor (D-p-Cl-Phe6, Leul7; 10 micromol L-1), a vasoactive intestinal peptide (VIP) receptor antagonist, and an inhibitor of haem oxygenase, (copper protoporphyrin IX; CuPP-IX; 10 micromol L-1), suggesting that nitric oxide (NO), VIP and carbon monoxide (CO), respectively, are released in response to EFS. Immunoreactivities for haem oxygenase-2 (HO-2) and VIP, and histochemical staining for NADPH diaphorase were observed in nerve cell bodies and fibres, demonstrating the presence of CO, VIP and NO as putative NANC neurotransmitters in dog gallbladder. These data support the hypothesis that NO, VIP and CO contribute to NANC relaxation of the canine gallbladder.

Iron deficiency transiently suppresses biliary neuronal nitric oxide synthase

BACKGROUND

Iron deficiency results in altered gallbladder and sphincter of Oddi (SO) motility and cholesterol crystal formation. In addition, gallbladder neuronal nitric oxide synthase (nNOS) has been shown to be markedly reduced after 8 weeks on an iron-deficient diet. However, the effects of prolonged iron deficiency on gallbladder and SO nNOS as well as crystal formation have not been determined. Therefore, we tested the hypothesis that iron deficiency would downregulate both gallbladder and SO nNOS expression and that nNOS downregulation and cholesterol crystal formation would progress over time.

MATERIALS AND METHODS

Thirty-eight adult female prairie dogs were fed either an ironsupplemented (Fe+) (200 ppm) or an iron-deficient (Fe-) (8 ppm) diet for 8 weeks (Fe+ n = 9, Fe- n = 10) or 16 weeks (Fe+ n = 9, Fe- n = 10). Blood hemoglobin (HbG) was measured; gallbladder cholesterol crystals were counted; and cholesterol saturation indices (CSI) were calculated. Gallbladder and SO nNOS levels were measured by Western blot.

RESULTS

The Fe+ prairie dogs had significantly higher HbG than the Fe- animals (16.9 +/- 0.6 g/dl vs 15.2 +/- 0.5 g/dl, respectively, P < 0.05) after 8 weeks. This difference was even greater after 16 weeks (16.1 +/- 0.4 g/dl vs 14.0 +/- 0.5 g/dl, P < 0.01). At 8 weeks, more cholesterol crystals per 10 HPF were observed in the Fe- animals (0.4 +/- 0.3 vs 1.6 +/- 0.4 per 10 HPF, P < 0.05). This difference was even greater after 16 weeks (0.0 +/- 0.0 vs 52.6 +/- 25.3 per 10 HPF, P < 0.01). No difference in the CSI was observed in the four groups. Iron deficiency decreased the nNOS/beta-actin protein levels in the gallbladder and SO at 8 weeks (57.0 +/- 29.6 vs 7.4 +/- 2.6, gallbladder, P < 0.05) (98.4 +/- 39.7 vs 29.9 +/- 11.0, SO, P = 0.09), but these levels returned to baseline at 16 weeks.

CONCLUSIONS

We conclude that iron deficiency acutely suppresses gallbladder and SO nNOS, and that compensatory mechanisms return nNOS to baseline levels while cholesterol crystal formation increases over time.

A redox-based mechanism for the contractile and relaxing effects of NO in the guinea-pig gall bladder

The purpose of this study was to determine the effects of sodium nitroprusside (SNP), 2,2'-(hydroxynitrosohydrazino)bis-ethanamine (DETA/NO) and 3-morpholinosydnonimine (SIN-1), NO donors which yield different NO reactive species (NO+, NO* and peroxynitrite, respectively), as well as exogenous peroxynitrite, on gall bladder contractility. Under resting tone conditions, SNP induced a dose-dependent contraction with a maximal effect (10.3 +/- 0.7 mN, S.E.M.) at 1 mM. Consistent with these findings, SNP caused a concentration-dependent depolarization of gall bladder smooth muscle. The excitatory effects of SNP were dependent on extracellular calcium entry through L-type Ca2+ channels. Furthermore, the contraction and depolarization were sensitive to tyrosine kinase blockade, and an associated increase in tyrosine phosphorylation was detected in Western blot studies. DETA/NO induced dose-dependent relaxing effects. These relaxations were sensitive to the guanylyl cyclase inhibitor 1H-[1,2,4]oxidiazolo[4,3-a]quinoxaline-1-one (ODQ, 2 microM) but they were not altered by treatment with the potassium channel blockers tetraethylammoniun (TEA, 5 mM) and 4-aminopyridine (4-AP, 5 mM). When tested in a reducing environment (created by 2.5 mM 1,4-dithiothreitol, DTT), SNP caused a relaxation of gall bladder muscle strips. Similarly, the SNP-induced contraction was converted to a relaxation, and associated hyperpolarization, when DTT was added during the steady state of an SNP-induced response. SIN-1 (0.1 mM), which has been shown to release peroxynitrite, induced relaxing effects that were enhanced by superoxide dismutase (SOD, 50 U ml(-1)). The relaxations induced by either SIN-1 alone or SIN-1 in the presence of SOD were strengthened by catalase (1000 U ml(-1)) and abolished by ODQ pretreatment. However, exogenous peroxynitrite induced a concentration-dependent contraction, which was dependent on activation of leukotriene (LT) metabolism and extracellular calcium. The peroxynitrite-induced contraction was abolished in the presence of the peroxynitrite scavenger melatonin. These results suggest that SIN-1 behaves as an NO* rather than a peroxynitrite source. We conclude that, depending on the redox state, NO has opposing effects on the motility of the gall bladder, being a relaxing agent when in NO * form and a contracting agent when in NO+ or peroxynitrite redox species form. Knowledge of the contrasting effects of the different redox forms of NO can clarify our understanding of the effects of NO donors on gall bladder and other smooth muscle cell types.

Review article: agents affecting gall-bladder motility--role in treatment and prevention of gallstones

Various agents may either enhance or impair post-prandial gall-bladder motility, and they are identified in this review. When studying the impact of medication on gall-bladder motility, the effects on interdigestive gall-bladder and intestinal motility should also be taken into account. Patients at high risk of gallstone disease, and patients who are treated chronically with gall-bladder motility inhibiting drugs, may benefit from improved gall-bladder motility using a prokinetic agent. However, there are no long-term studies to prove that such a strategy prevents gallstone formation.

Review article: control of gall-bladder motor function

Muscular contraction of the gall-bladder is the primary determinant of bile delivery into the duodenum. Where bile goes following its secretion by the liver depends upon a co-ordinated series of pressure interrelations between the hepatic secretory pressure at the entrance to the biliary system, a low pressure conduit, and the pressure differences between the gall-bladder, cystic duct and sphincter of Oddi. During fasting, the relatively higher tone in the sphincter of Oddi fosters the entry of bile into the gall-bladder. The gall-bladder accommodates this influx without an increase in intravesicular pressure through its compliance or distensibility, which consists of active muscle relaxation and passive fibroelastic components. The concentrating function of the gall-bladder keeps the volume small. Once about every 120 min during the interdigestive period, gall-bladder emptying occurs coincident with intense duodenal contractions; all part of the migratory myoelectric complex. This helps maintain the enterohepatic circulation of bile salts. Motilin, which mediates these events during fasting, acts by stimulating intrinsic cholinergic nerves. Cholecystokinin is the major determinant of gallbladder emptying with eating. Cholecystokinin acts through pre-ganglionic cholinergic nerves, to initiate gall-bladder contraction. Agonists like cholecystokinin and acetylcholine cause contraction of gall-bladder smooth muscle through signal transduction, which increases intracellular calcium levels and so initiates the contractile machinery. Cholecystokinin also acts on the sphincter of Oddi via pre-ganglionic cholinergic nerves to release vasoactive intestinal polypeptide and nitric oxide, and so lower tone. These events are co-ordinated with motility and secretory events in the upper gastrointestinal tract, delivering bile at appropriate times into the duodenum.

Gallbladder hyporesponsiveness to an exogenous nitric oxide donor, glyceryl trinitrate, in patients with advanced liver cirrhosis

OBJECTIVE

An increased production of nitric oxide (NO) in liver cirrhosis has been documented. NO could intervene in regulating gallbladder contraction, as suggested by clinical and experimental studies. Our aim was to investigate the influence of an NO donor on gallbladder motility in cirrhotic patients in relation to the severity of liver cirrhosis.

METHODS

The subjects were six controls and 18 patients with liver cirrhosis (six in each Child class). Gallbladder emptying was monitored by ultrasound for 90 min after a mixed meal (14 g fat, 425 kcal). Fasting gallbladder volume, minimal residual volume, ejection fraction, area under emptying curve, and half contraction time of the gallbladder were assessed at 15-min intervals. The patients were evaluated on two consecutive days, with or without perlingual administration of 0.5 mg glyceryl trinitrate (GTN). Statistical analysis was performed by the two-tailed Student's t test and Pearson's correlation coefficient.

RESULTS

GTN significantly reduced gallbladder motility in controls and compensated cirrhotics (p < 0.02), but had no effect upon gallbladder emptying in Child class B and C cirrhotics.

CONCLUSIONS

Gallbladder hypocontractility in liver cirrhosis is related to the severity of the disease. This study is the first to show that GTN has no effect upon gallbladder motility in advanced liver cirrhosis when administered in doses that induce relaxation in controls and compensated cirrhosis.