Renal function in the hibernating, and hypothermic hamster Mesocricetus auratus

Area of Science:

• Physiology
• Comparative Biology
• Renal Function

Background:

• Hibernation and hypothermia induce significant metabolic depression.
• Understanding renal solute handling during these states is crucial for survival.

Purpose of the Study:

• To examine plasma and urine electrolyte (Na+, K+) and urea concentrations in hibernating, hypothermic, and normothermic hamsters.
• To investigate the renal corticomedullary solute gradient under these conditions.

Main Methods:

• Measurement of plasma and urine Na+, K+, and urea in hamsters at different temperatures (normothermic, hypothermic, hibernating).
• Analysis of renal tissue slices to assess corticomedullary solute gradients.
• Comparison of solute concentrations between control, hypothermic, and hibernating states, including rewarming phases.

Main Results:

• Plasma Na+ and K+ were largely unaffected by short-term hypothermia but increased in hibernators.
• Plasma urea increased significantly in both hypothermic and hibernating hamsters.
• The renal corticomedullary solute gradient for Na+ and urea was eliminated or reduced during hypothermia and hibernation, returning to normal upon rewarming to 37°C.
• Renal K+ concentration decreased from cortex to papilla, with higher cortical K+ in hypothermic and hibernating animals.

Conclusions:

• Hypothermia and hibernation significantly alter plasma and renal solute concentrations and distribution.
• The renal corticomedullary solute gradient is disrupted during metabolic depression but is reversible upon rewarming.
• These findings provide insights into renal adaptation mechanisms during extreme physiological states.