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Neuromodulators and hypoxic hypothermia in the rat
1Atelier de Physiologie Respiratoire, Faculté de Médecine Saint-Antoine, Paris, France.
Respiration Physiology
|September 28, 1998
Summary
Opioids and adenosine play a minor role in hypoxic hypometabolism and hypothermia in rats, particularly during cold exposure. Blocking these pathways slightly reduced the effects of hypoxia.
Area of Science:
- Physiology
- Environmental Medicine
- Pharmacology
Background:
- Hypoxia can induce hypometabolism and hypothermia.
- The roles of endogenous opioids and adenosine in these responses are not fully understood.
Purpose of the Study:
- To investigate the involvement of opioids and adenosine in hypoxia-induced hypometabolism in rats.
- To determine if opioid antagonists or adenosine antagonists alter the physiological responses to hypoxia.
Main Methods:
- Adult rats were exposed to ambient hypoxia (AHx) or carbon monoxide hypoxia (COHx) at different temperatures.
- Rats were injected with naloxone (NLX), an opioid antagonist, or theophylline (THEO), an adenosine antagonist.
- Oxygen consumption, ventilation, colonic temperature, and shivering were measured.
Main Results:
- Naloxone reduced hypoxic hypometabolism during ambient hypoxia at 26°C and slightly decreased it during CO hypoxia at 9°C.
- Theophylline slightly reduced hypoxic hypometabolism during both AHx and COHx at 9°C.
- Neither antagonist consistently affected the ventilatory response to hypoxia.
Conclusions:
- Adenosine and opioids play a minor role in mediating hypoxia-induced hypometabolism and hypothermia.
- These effects are more pronounced during cold exposure.