Absorption delays could impair perfusion

After heat exposure, this proposed hypothesis asks whether drinking the same amount of fluid on different schedules can leave the kidneys and brain temporarily undersupplied because water is still in the gut rather than the bloodstream. The comparison would keep swallowed volume equal, then measure labeled water reaching circulation, fluid left in the stomach, kidney filtration, and blood flow recovery in the brain. If matching water’s arrival in circulation erases schedule-related differences in filtration and brain recovery, delayed gut delivery would gain support. A route-changing test could bypass the gut while keeping venous pressure unchanged. Restored filtration under that condition would help separate this mechanism from explanations centered on pressure.