Hypoxic tolerance enhanced by beta-hydroxybutyrate-glucagon in the mouse

Area of Science:

• Physiology
• Biochemistry
• Metabolism

Background:

• A correlation exists between elevated blood ketones and enhanced tolerance to hypoxia in mice.
• Previous studies noted increased hypoxic tolerance in fasted, alloxan-diabetic, or 1,3-butanediol-treated mice, all exhibiting ketosis.

Purpose of the Study:

• To investigate if direct elevation of blood ketones using beta-hydroxybutyrate (BHB) can increase hypoxic tolerance.
• To explore the combined effect of glucagon (G) and BHB on hypoxic tolerance, considering their association with fasting and diabetes.

Main Methods:

• Mice were administered intravenous (IV) or intraperitoneal (IP) beta-hydroxybutyrate (BHB) to elevate blood ketone levels.
• Hypoxic tolerance tests were conducted on mice receiving G alone, BHB alone, or a combination of G plus BHB.

Main Results:

• Administration of BHB alone did not result in increased hypoxic tolerance.
• Mice treated with glucagon (G) alone also showed no significant difference in hypoxic survival times compared to controls.
• Mice receiving the combination of G plus BHB exhibited significantly increased hypoxic survival times.

Conclusions:

• Direct elevation of blood ketones with BHB alone is insufficient to enhance hypoxic tolerance.
• The combination of glucagon and beta-hydroxybutyrate significantly increases hypoxic tolerance in mice.
• The observed increase in hypoxic tolerance with G plus BHB suggests a complex interaction beyond a simple glucagon-mediated alteration of blood BHB levels.