Regulation of Intestinal and Hepatic Lipoprotein Production by Glucose and Fructose

Each subject will be studied twice 4-6 weeks apart in random order in this single blinded study. A nasoduodenal tube will be sited under fluoroscopic guidance the day prior to the study.In study A they will receive intraduodenal intralipid (20% at 60 ml/hour) alongside 60 ml/hour of 20% dextrose or fructose for 15 hours starting at 4am. In study B they will receive 60 ml/hour of intraduodenal intralipid with 60ml/hour of normal saline for 15 hours from 4am. A pancreatic clamp (octreotide with replacement glucose, insulin, glucagon and growth hormone) will be started at 7am. From 9am an iv bolus of deuterated-glycerol (d5-glycerol) along with a regular infusion of deuterated leucine (L-[5,5,5-2H3]. Regular blood samples will be drawn to assess lipoprotein kinetics.

Inclusion criteria

• Men and women, aged 18 to 60 years
• Body mass index 20 kg/m2 to 27 kg/m2
• Hemoglobin above 130g/L.
• Normal glucose tolerance in response to a 75g, 2-hr OGTT

Exclusion criteria

• Subject has a history of hepatitis/hepatic disease that has been active within the previous two years.
• Any significant active (over the past 12 months) disease of the gastrointestinal, pulmonary, neurological, renal (Cr > 1.5 mg/dL), genitourinary, hematological systems, or has severe uncontrolled treated or untreated hypertension (sitting diastolic BP > 100 or systolic > 180) or proliferative retinopathy
• History of diabetes or OGTT indicative of diabetes or impaired glucose tolerance.
• Any history of a MI or clinically significant, active, cardiovascular history including a history of arrhythmia's or conduction delays on ECG, unstable angina, or decompensated heart failure.
• Any laboratory values: AST > 2x ULN; ALT > 2x ULN TSH > 6 mU/l
• Current addiction to alcohol or substances of abuse as determined by the investigator.
• Mental incapacity, unwillingness or language barrier precluding adequate understanding or cooperation
• Taking any prescription or non-prescription medications at the time of the study
• Having donated blood three months prior to and three months post study procedures
• A pregnancy test will be performed 1 to 3 days prior to each study in all female subjects. Those who test positive for pregnancy will be excluded.

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