Hypobaric hypoxia reduces GLUT2 transporter content in rat jejunum more than in ileum

Impact of airplane cabin pressure on biliary motility in rabbits

AIM: To observe the effect of the change in barometric pressure on biliary motility by using a hypobaric chamber to simulate a civil aircraft in flight.

METHODS: Forty-two rabbits were randomly divided into a control group (n = 14), a Ta group (n = 14, hypobaric exposure in a hypobaric chamber 3 times in 3 d) and a Tb group (n = 14, hypobaric exposure in a hypobaric chamber 7 times in 7 d). The level of cholecystokinin 8 (CCK8) was measured in the duodenal tissue and plasma. The expression of CCK-A receptor (CCK-AR) mRNA in gallbladder tissues was detected by RT-PCR. Quantitative analysis of 99mTc-EHIDA hepatobiliary dynamic imaging was made in each group.

RESULTS: Compared to the control group, the Ta group had lower levels of CCK8 both in duodenal tissue and plasma (Ta group vs C group, 5.24 pg/mL ± 0.56 pg/mL vs 6.25 pg/mL ± 0.53 pg/mL in duodenal tissue, P < 0.05; 3.59 pg/mL ± 0.20 pg/mL vs 4.61 pg/mL ± 0.10 pg/mL in plasma, P < 0.05) and a significant delay in duodenal appearance time (Ta group vs C group, 114.73 s ± 13.34 s vs 79.52 s ± 10.83 s, P < 0.05). Besides a delay in DAT and lower level of CCK8, decreased expression of CCK-A receptor mRNA was found in gallbladder tissues in the Tb group compared to the control group and Ta group (CCK-AR/β-actin: Tb group vs C group: 0.56 ± 0.21 vs 0.82 ± 0.16, P < 0.05; Tb group vs Ta group: 0.56 ± 0.21 vs 0.75 ± 0.29, P < 0.05).

CONCLUSION: Barometric pressure change in a civil aircraft in flight shows some inhibitory effects on biliary motility.

Identification of a novel sodium-dependent fructose transport activity in the hepatopancreas of the Atlantic lobster Homarus americanus

[(3)H]Fructose and [(3)H]glucose transport were determined in brush-border membrane vesicles (BBMV), basolateral membrane vesicles (BLMV) and isolated cells (E, R, F, B) of H. americanus (Atlantic lobster) hepatopancreas. Glucose transport in BBMV was equilibrative in the absence of sodium and concentrative in the presence of sodium. Sodium-dependent glucose transport by BBMV was not inhibited by a tenfold molar excess of fructose. Glucose transport by BLMV was equilibrative and sodium independent. Fructose uptake by BBMV and BLMV was equilibrative in the absence of sodium and concentrative in the presence of sodium. This enhancement was not affected by a tenfold molar excess of glucose in the presence of sodium. E-, F- and B-cells showed sodium-dependent uptake of fructose, while R-cells did not. Sodium-dependent fructose uptake by E-cells was not inhibited by a tenfold molar excess of glucose or mannose. Western blot analysis of BBMV, BLMV and E-, R-, F- and B-cells using rabbit polyclonal antibodies directed against epitopes of mammalian GLUT2, GLUT5, SGLT1 and SGLT4 indicated the presence of cross-reacting lobster proteins. Sequence alignment of the mammalian proteins with translated, lobster expressed sequence tags also indicated significant identity between species. Comparison of fructose and glucose uptake in the absence and presence of sodium by BBMV, BLMV and isolated cells indicated the presence of a distinct sodium-dependent transport activity for each sugar in the Atlantic lobster.