Short communication: Storage time and temperature affect plasma osmolality values in field-collected blood samples.

Area of Science:

• Environmental physiology
• Wildlife biology
• Ecological research

Background:

• Climate change impacts habitat hydrology, necessitating understanding of animal hydric physiology.
• Plasma osmolality is a key hydration indicator, but sample storage effects are understudied, especially in field contexts.

Purpose of the Study:

• To investigate the stability of plasma osmolality in wild rattlesnake samples under different storage conditions.
• To determine the impact of time and temperature on plasma osmolality integrity for ecological studies.

Main Methods:

• Rattlesnake plasma samples were stored in plastic tubes at 2°C (refrigerated) and -18°C (frozen).
• Samples were analyzed for osmolality at 0, 2, 3, 7, and 29 days.
• Changes in osmolality were compared to baseline values and between temperature treatments.

Main Results:

• Plasma osmolality increased significantly over time at both refrigeration and freezing temperatures.
• Contrary to hypothesis, frozen samples exhibited a greater increase in osmolality than refrigerated samples after 7 days.
• Osmolality values deviated significantly from baseline after 7 days of storage.

Conclusions:

• Extended storage, particularly freezing, can alter plasma osmolality readings in wildlife samples.
• For accurate hydration assessment in field studies, refrigerate plasma samples for 3 days or less.
• Further research is needed to understand the mechanisms behind osmolality changes during plasma storage.