Volume 118, Issue 1, Pages 173-182 (January 2000) Postprandial chylomicron formation and fat absorption in multidrug resistance gene 2 P- glycoprotein–deficient mice  Peter J. Voshol, Deanna M. Minich, Rick Havinga, Ronald P.J.Oude Elferink, Henkjan J. Verkade, Albert K. Groen, Folkert Kuipers  Gastroenterology  Volume 118, Issue 1, Pages 173-182 (January 2000) DOI: 10.1016/S0016-5085(00)70426-4 Copyright © 2000 American Gastroenterological Association Terms and Conditions

Fig. 1 Plasma triglyceride concentrations in mice after an intragastric lipid load (200 μL olive oil) at time 0. Blood samples were drawn every hour, and plasma triglyceride concentrations were determined using a commercially available assay kit. Values represent means ± SD; n = 6 per group. ○, Mdr2(+/+) mice; ●, Mdr2(+/−) mice; ●, Mdr2(−/−) mice. *P < 0.05, significant differences between Mdr2(−/−) and Mdr2(+/−)/Mdr2(+/+) mice at 1 and 2 hours (ANOVA and Newman–Keuls t test post hoc analysis). Statistical analysis was performed using SPSS software. Gastroenterology 2000 118, 173-182DOI: (10.1016/S0016-5085(00)70426-4) Copyright © 2000 American Gastroenterological Association Terms and Conditions

Fig. 2 Changes in postprandial plasma triglyceride concentrations in Mdr2(−/−) mice after an intraduodenal lipid load (200 μL olive oil) at time 0 during infusion of either whole rat bile or saline. The lipid load was administered 2 hours after the start of infusion (see Materials and Methods). The infused rat bile was collected overnight from a rat with long-term bile diversion.23 Values represent Δ values at the different times compared with time 0 (mean ± SD; n = 4 per group). ○, Saline; ●, rat bile. *P < 0.05, significant differences between saline- and bile-infused mice at 2 and 3 hours (Mann–Whitney U test). Statistical analysis was performed using SPSS software. Gastroenterology 2000 118, 173-182DOI: (10.1016/S0016-5085(00)70426-4) Copyright © 2000 American Gastroenterological Association Terms and Conditions

Fig. 3 Plasma appearance of 3H-triglycerides after an intragastric load of olive oil containing 3H-triolein and an intravenous injection of Triton WR1339 at time 0. Blood samples were drawn every hour, and lipids were extracted from plasma after Bligh and Dyer extraction. Thin-layer chromatography was performed to isolate the triglyceride fraction for determination of radioactivity by scintillation counting. Scanning of the thin-layer plates indicated that essentially all of the 3H label was in the triglyceride fraction. Values represent disintegrations per second per milliliter of plasma as determined by scintillation counting (mean ± SD; n = 5 per group). ○, Mdr2(+/+) mice; ●, Mdr2(+/−) mice; ●, Mdr2(−/−) mice. *P < 0.05, significant differences between Mdr2(−/−) and Mdr2(+/−)/Mdr2(+/+) mice at 2, 3, and 4 hours (ANOVA and Newman–Keuls t test post hoc analysis). Statistical analyses were performed using SPSS software. Gastroenterology 2000 118, 173-182DOI: (10.1016/S0016-5085(00)70426-4) Copyright © 2000 American Gastroenterological Association Terms and Conditions

Fig. 4 3H-triglyceride content of (A) the small intestinal lumen, (B) small intestinal wall, and (C) plasma at different time points after intragastric installation of 3H-triolein–labeled olive oil in Mdr2(+/+) and Mdr2(−/−) mice. Small intestines and plasma were collected at indicated time points after an intragastric olive oil load containing 3H-triolein and intravenously injected Triton WR1339, as outlined in Materials and Methods. The small intestine was flushed with 5 mmol/L taurocholate to eliminate residual luminal 3H label. The tissues were homogenized, and 3H-triglyceride contents in luminal wash, tissue homogenates, and plasma samples were measured by scintillation counting. Total recovery of radioactivity (stomach, small intestine, large intestine, taurocholate wash, plasma, and liver) exceeded 86% of the administered dose in all experiments. Values represent percentages of dose in the intestinal lumen wash, tissue homogenates, and plasma 1, 2, and 4 hours after intragastric administration; n = 4 per group. ○, Mdr2(+/+) mice; ●, Mdr2(−/−) mice. *P < 0.05, significant differences between Mdr2(−/−) and Mdr2(+/+) mice (Mann–Whitney U test). Statistical analysis was performed using SPSS software. Gastroenterology 2000 118, 173-182DOI: (10.1016/S0016-5085(00)70426-4) Copyright © 2000 American Gastroenterological Association Terms and Conditions

Fig. 4 3H-triglyceride content of (A) the small intestinal lumen, (B) small intestinal wall, and (C) plasma at different time points after intragastric installation of 3H-triolein–labeled olive oil in Mdr2(+/+) and Mdr2(−/−) mice. Small intestines and plasma were collected at indicated time points after an intragastric olive oil load containing 3H-triolein and intravenously injected Triton WR1339, as outlined in Materials and Methods. The small intestine was flushed with 5 mmol/L taurocholate to eliminate residual luminal 3H label. The tissues were homogenized, and 3H-triglyceride contents in luminal wash, tissue homogenates, and plasma samples were measured by scintillation counting. Total recovery of radioactivity (stomach, small intestine, large intestine, taurocholate wash, plasma, and liver) exceeded 86% of the administered dose in all experiments. Values represent percentages of dose in the intestinal lumen wash, tissue homogenates, and plasma 1, 2, and 4 hours after intragastric administration; n = 4 per group. ○, Mdr2(+/+) mice; ●, Mdr2(−/−) mice. *P < 0.05, significant differences between Mdr2(−/−) and Mdr2(+/+) mice (Mann–Whitney U test). Statistical analysis was performed using SPSS software. Gastroenterology 2000 118, 173-182DOI: (10.1016/S0016-5085(00)70426-4) Copyright © 2000 American Gastroenterological Association Terms and Conditions

Fig. 4 3H-triglyceride content of (A) the small intestinal lumen, (B) small intestinal wall, and (C) plasma at different time points after intragastric installation of 3H-triolein–labeled olive oil in Mdr2(+/+) and Mdr2(−/−) mice. Small intestines and plasma were collected at indicated time points after an intragastric olive oil load containing 3H-triolein and intravenously injected Triton WR1339, as outlined in Materials and Methods. The small intestine was flushed with 5 mmol/L taurocholate to eliminate residual luminal 3H label. The tissues were homogenized, and 3H-triglyceride contents in luminal wash, tissue homogenates, and plasma samples were measured by scintillation counting. Total recovery of radioactivity (stomach, small intestine, large intestine, taurocholate wash, plasma, and liver) exceeded 86% of the administered dose in all experiments. Values represent percentages of dose in the intestinal lumen wash, tissue homogenates, and plasma 1, 2, and 4 hours after intragastric administration; n = 4 per group. ○, Mdr2(+/+) mice; ●, Mdr2(−/−) mice. *P < 0.05, significant differences between Mdr2(−/−) and Mdr2(+/+) mice (Mann–Whitney U test). Statistical analysis was performed using SPSS software. Gastroenterology 2000 118, 173-182DOI: (10.1016/S0016-5085(00)70426-4) Copyright © 2000 American Gastroenterological Association Terms and Conditions

Fig. 5 Representative small intestinal sections of (A) Mdr2(+/+) and (B) Mdr2(−/−) mice collected approximately 30 cm distal from the stomach 4 hours after administration of an intragastric olive oil load. The small intestine was flushed with ice-cold PBS and immediately frozen at −80°C. The 4-μm sections were stained with ORO and counterstained with hematoxylin (original magnification 120×). Arrowheads indicate (A) the small fat droplets in the intestinal interstitium of Mdr2(+/+) mice and (B) the large fat droplets in the enterocytes of Mdr2(−/−) mice. Gastroenterology 2000 118, 173-182DOI: (10.1016/S0016-5085(00)70426-4) Copyright © 2000 American Gastroenterological Association Terms and Conditions