Aging and Gastrointestinal Barrier Function

Heat waves are lethal and cause a disproportionate number of deaths in the elderly relative to any other age group. Although gastrointestinal barrier dysfunction is a primary cause of heat related illness, little is known about the effects of aging on gastrointestinal barrier function during hyperthermia. The central hypothesis of this work is that the elderly exhibit greater gastrointestinal barrier dysfunction during hyperthermia. Participants will complete a control trial where gastrointestinal permeability (without heating) will be assessed in young and older adults. In the experimental trial, controlled hyperthermia will be achieved using a water perfused, tube lined suit. Core body temperature will be raised to a maximum of 2 degrees Celsius above the baseline value, or an absolute temperature of 39.5 degrees Celsius. Core temperature will not be collected during the control trial. Comprehensive assessments of gastrointestinal barrier function and systemic inflammation will be assessed in young and older adults. The expected outcome of this work will re-shape our understanding of the consequences of aging on gastrointestinal barrier function during heat waves.

Inclusion criteria

• Healthy male and female individuals
• 18-35 years or 65+ years of age
• Free of any underlying moderate to serious medical conditions

Exclusion criteria

• Known heart disease
• Any chronic medical conditions requiring regular medical therapy including cancer, diabetes, uncontrolled hypertension, inflammatory bowel disease, and uncontrolled hypercholestrolmia etc;
• Abnormality detected on routine screening suggestive of provocable ischemia or previously undetected cardiac disease or resting left bundle branch block on screening electrocardiogram.
• Current smokers, as well as individuals who regularly smoked within the past 3 years
• Subject with a body mass index ≥35 kg/m2
• Pregnant
• Use of immunosuppressant drugs within last 4 weeks prior to screening
• Use of antibiotics or antimicrobial medication in last month
• Any previous abdominal surgery
• Use of steroids in last 6 weeks
• Regular use of probiotics in last month
• Use of laxatives or anti-diarrhetic in last month