Hyperglycemia and Mitochondrial Function in The Endothelium of Humans

Study Overview
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Brief Summary
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In this study, the investigators will test the hypothesis that acute in vivo exposure to hyperglycemia increases mitochondrial network fragmentation and mitochondrial reactive oxygen species production (ROS) production in human arterial endothelial cells.

Detailed Description
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Subjects will be recruited according to our inclusion/exclusion criteria. The investigators employ a multifaceted approach to recruitment, including flyers, community newspaper ads, internet ad postings, and direct recruitment from the Internal Medicine Clinics of Froedtert Memorial Lutheran Hospital/Medical College of Wisconsin which saw approximately 50,000 unique outpatient visits over last year. The electronic health record is leveraged to identify potential subjects by HIPAA guidelines and Medical College of Wisconsin policies. Potential subjects will undergo phenotyping that includes a detailed medical history, anthropomorphic measurements, blood pressure and heart rate measurements, and a blood draw for measurements that include fasting lipids, glucose, and glycosylated hemoglobin, creatinine, and liver function tests. Healthy, non-DM subjects who pass the screening as per the inclusion/exclusion criteria in Table 2 will be enrolled in the study protocol. Following an overnight fast (12 hours), subjects will come in the morning to our Adult Translational Research Unit (A-TRU) which is part of the Clinical Translational Research Initiative of Southeast Wisconsin (8UL1TR000055). An antecubital intravenous line will be placed to facilitate blood glucose sampling during the hyperglycemic challenge. An antecubital intravenous catheter will be placed to facilitate obtaining endothelial cells from the vein by J-wire biopsy for of mitochondrial testing. The principal investigator has published experience with the J-wire endothelial cell biopsy technique, and the technique has been extensively validated technique. An initial venous glucose sample will be taken from the antecubital vein and an initial J-wire biopsy of the radial artery endothelium will be performed through the radial arterial line. Subjects will then be asked to drink a standardized 75 g glucose drink created by the A-TRU nutritionist- a standard oral glucose challenge as used clinically. Blood glucose samples will be taken hourly after that until 4 hours post drink ingestion. At one and 4 hours post-ingestion, J-wire endothelial biopsies of the radial artery will be repeated. Four separate J wires will be passed into the radial artery for each measurement time point (0,1, and 4 hours). In non-diabetic subjects, the 75 g oral challenge induces a peak increase in systemic glucose at 1-hour post-administration at which time endothelial dysfunction is concomitantly detectable. Endothelial cells will be obtained via J-wire capture technique. A portion of the endothelial cells isolated from the J-wires will be used to measure mitochondrial network complexity prior hyperglycemic challenge, 1-hour post challenge, and 4 hours post challenge. The investigators will visualize the mitochondrial networks in these cells using our previously reported and validated immunofluorescence method using cytochrome c antibodies to tag the mitochondria. Network fragmentation (high number=greater fragmentation and fission) will be quantified by network fragmentation count calculated with ImageJ (NIH, Bethesda) using a validated protocol.

Official Title
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Hyperglycemia and Mitochondrial Function in The Endothelium of Humans

Conditions
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Diabetes, Hyperglycemia

Intervention / Treatment
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* Other: 75 g glucose solution


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Adult age 21 to 70 No evidence of metabolic syndrome or diabetes, hypertension (BP≥140/90), or high cholesterol (LDL≥160) at the time of screening. Exclusion Criteria: History of stroke, peripheral arterial disease, or coronary artery disease (as defined by the presence of at least one coronary stenosis ≥ 40% on angiography or by confirmed history of myocardial infarction by standard criteria). History of bleeding disorders. Evidence of other evident major illness including chronic renal insufficiency (plasma creatinine > 1.4 for women or 1.5 for men), liver disease (liver enzymes greater than 2.5 x normal), and cancer currently undergoing therapy or had therapy for cancer within 1 year of enrollment. Pregnancy as determined by urinary human chorionic gonadotropin beta test Thienopyridine, anti-thrombin/Xa, or warfarin therapy at time of screening On medication for cholesterol or blood pressure

Ages Eligible for Study
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Minimum Age: 21 Years
Maximum Age: 70 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Healthy Subjects<br>Healthy subjects meeting inclusion criteria will be administered a 75 g glucose solution one time (orally). Subjects will be ages 21-70 years with no evidence of diabetes, hypertension, metabolic syndrome, or high cholesterol at the time of screening. Potential subjects with a history of atherosclerotic disease, chronic renal insufficiency (plasma creatinine > 1.5 men, > 1.5 women), liver enzymes > 2.5x normal, pregnant at the time of screening will be excluded | Other: 75 g glucose solution<br>* This is the same as the standard oral glucose challenge dose and route given clinically<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| change in mitochondrial network complexity of endothelial cells as measured by mitochondrial network fragment ratio | The investigators visualize the mitochondrial network complexity in these cells using our previously reported and validated immunofluorescence method using cytochrome c antibodies to tag the mitochondria. Network fragmentation (total number of fragments/ total fluorescent pixels*100) will be quantified by network fragmentation count calculated with ImageJ (NIH, Bethesda) using a validated protocol. | Measured at 0,1, and 4 hours after administration |