Investigation of endogenous neurotransmitters of guinea pig gallbladder using nicotinic agonist stimulation

Effect of portal azygous disconnection on gallbladder motor function

AIM: To investigate and clarify the effect of vagus on gallbladder motility through a comparative study.

METHODS: Twenty-three hepatocirrhosis patients with portal hypertension were included in this study. In Hassab operation group, the anterior and posterior trunk of vagus were surgically excised (H, n = 18); In vena coronaria ventriculi embolization group, the vena coronaria ventriculi bole was ligated and injected TH adhesive (8 mL) after splenectomy (VCE, n = 5). Before operation and 10 d after operation, ^99mTc-labeled diethyl acetyl acid anilide iminodiacetic acid (^99mTc-EHIDA, 185 MBq) was administered intravenously to the patients, and then scintigraphic method was used to assess the motor function of gallbladder. The index including radiocounting 30 min after injected ^99mTc-EHIDA (GBRC 30min), emptying fraction (GBEF), emptying period (GBEP), emptying rate (GBER), latent period (GBLP), latent period radiocounting increment (GBLI) and latent period radiocounting increment rate (GBLR) were analyzed.

RESULTS: GBRC 30 min in H group was significantly lower after operation than that before operation (74.8 ± 66.9 vs 155.7 ± 72.9,P < 0.05); GBLP was very short in pre-operation, and GBLP prolonged significantly after operation (13.36 ± 5.92 vs 2.24 ± 1.48, P < 0.01); the gallbladder radiocounting increased gradually during GBLP; the GBLI and GBLP level were very low before operation, but the GBLI and GBLP increased significantly after operation (79.5 ± 56.3 vs 9.2 ± 11.7, 113.4 ± 49.5 vs 7.6 ± 10.8, P < 0.01); GBEP shortened significantly after operation (18.5 ± 6.3 vs 24.1 ± 6.4, P < 0.05); GBEF and GBER decreased obviously after operation (13.1 ± 5.4 vs 32.3 ± 16.3, 0.7 ± 0.3 vs 1.4 ± 0.8, P < 0.01). The preceding parameters in VCE group had no significant difference before and after operation (P > 0.05).

CONCLUSION: The gallbladder tension weakens obviously in interdigestive phase after the vagus is excised; the gallbladder contraction delays, and the motor function weakens obviously after meals.

Gallbladder motility in patients with hepatic cirrhosis before and after portal azygous disconnection

AIM: To determine and compare the effect of vagus nerve on gallbladder motility in patients with hepatic cirrhosis before and after portal azygous disconnection (PAD).

METHODS: PAD operation (or Hassab’s operation) was performed on 18 patients with portal hypertension, and anterior and posterior vagal trunks were cut. On d 3 before operation and d 10 after operation, ^99mTc-EHIDA 185 MBq was administered intravenously to the patients, and scintigraphy was performed at 0.25 min/frame. A standard fat meal was administered 30 min after scintigraphy, and dynamic imaging was performed 60 min after the fat meal. Following appearance of the region of interest (ROI) in gallbladder, the time-activity curve of ROI was established. The following seven parameters were used: Radioactivity at 30 min after injection of ^99mTc-EHIDA (RC 30min), bile emptying fraction (EF), bile emptying period (EP), emptying rate (ER), latent period (LP), latent period radiocounting increment (LI), and latent period radiocounting increment rate (LR).

RESULTS: The RC 30 min decreased significantly after operation, compared with that before operation (2 693.6 ± 2 406.9 vs 5 606.8 ± 2 625.4, P < 0.05). The radiocounting of gallbladder increased gradually during LP. LP after operation was significantly longer than that before operation (13.36 ± 5.92 vs 2.24 ± 1.48, P < 0.01). LI and LR after operation were significantly higher than those before operation (2 861.62 ± 028.3 vs 331.21 ± 421.02, and 113.42 ± 49.52 vs 7.57 ± 10.75, respectively, both P < 0.01). EP after operation was significantly shorter than that before operation (18.5 ± 6.3 vs 24.1 ± 6.4, P < 0.05). EF and ER after operation were significantly lower than those before operation (13.1 ± 5.4 vs 32.3 ± 16.3, and 0.7 ± 0.3 vs 1.4 ± 0.8, respectively, both P < 0.01).

CONCLUSION: PAD operation is a good clinical model in studying the effect of vagus on gallbladder motility. The gallbladder tension after PAD operation decreases significantly during the interdigestive phase. The latent period of gallbladder contraction prolongs and the motility weakens apparently after a standard fat meal. Human vagus influences the gallbladder motility, and cutting of the nerve inhibits the gallbladder motility.

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Muscarinic receptor knockout mice: role of muscarinic acetylcholine receptors M(2), M(3), and M(4) in carbamylcholine-induced gallbladder contractility

Muscarinic receptors play a major role in gallbladder function, although the muscarinic receptor(s) mediating smooth muscle contractility is unclear. This study compared smooth muscle contractile responses to carbamylcholine (10(-7)-10(-3) M) in isolated gallbladder from wild-type and M(2), M(3), and M(4) receptor knockout mice. Carbamylcholine-induced contraction in gallbladder was associated with tachyphylaxis and the release of a cyclooxygenase product because indomethacin (10(-6) M) inhibited carbamylcholine-induced contraction. The M(3) receptor was the major muscarinic receptor involved in contraction because carbamylcholine-induced contractility was inhibited in gallbladder from M(3) receptor knockout mice. Furthermore, the muscarinic receptor antagonists 11-[[[2-diethylamino-O-methyl]-1-piperidinyl]acetyl]-5,11-dihydrol-6H-pyridol[2,3-b][1,4]benzodiazepine-6-one (AF-DX 116) and pirenzepine dextrally shifted contraction to carbamylcholine in gallbladder from wild-type, M(2), and M(4) receptor knockout mice, with affinities consistent with M(3) receptor interaction. In addition, maximal contraction to carbamylcholine was reduced in gallbladder from M(2) receptor knockout mice and affinities for AF-DX 116 and pirenzepine in gallbladder from M(3) receptor knockout mice were consistent with their affinities at M(2) receptors. In M(4) receptor knockout mice, contraction to carbamylcholine was dextrally shifted, although the affinities for AF-DX 116 and pirenzepine in gallbladder from M(2) or M(3) knockout mice were not similar to their affinities at M(4) receptors. The M(4) receptor may serve as an accessory protein necessary for optimal potency of M(2) and M(3) receptor-mediated responses. Thus, muscarinic receptor knockout mice provided direct and unambiguous evidence that M(3), and to a lesser extent, M(2) receptors are the predominant muscarinic receptors mediating gallbladder contractility, and M(4) receptors appear necessary for optimal potency of carbamylcholine in gallbladder contraction.