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Circulating endogenous opioids and ventilatory response to CO2 and hypoxia
Respiration Physiology
|July 1, 1985
Summary
Circulating endogenous opioids, such as beta-endorphin (BE) and met-enkephalin (MET), do not significantly influence the human control of breathing during hypercapnia or hypoxia. Blood levels of these opioids remained unchanged after respiratory challenges in normal subjects.
Area of Science:
- Respiratory Physiology
- Neuroendocrinology
Background:
- The precise role of endogenous opioids in regulating respiratory control remains unclear.
- Recent advancements in radioimmunoassay techniques allow for the measurement of beta-endorphin (BE) and met-enkephalin (MET).
Purpose of the Study:
- To investigate the relationship between circulating levels of BE and MET and ventilatory responses to hypercapnia and hypoxia in healthy individuals.
- To determine if endogenous opioid levels change following respiratory challenges.
Main Methods:
- Ventilatory responses to hypercapnia (n=9) and hypoxia (n=7) were assessed using standard rebreathing techniques.
- A voluntary isocapnic normoxic hyperventilation test served as a control condition.
- Blood samples were analyzed for BE and MET levels before and up to 30 minutes after each test.
Main Results:
- Basal blood levels of BE and MET showed no correlation with the magnitude of ventilatory responses to hypercapnia or hypoxia.
- No significant alterations in BE or MET levels were observed following the hypercapnic, hypoxic, or hyperventilation tests.
Conclusions:
- Circulating endogenous opioids (BE and MET) do not appear to play a significant role in the control of breathing in normal humans.
- These findings suggest that while circulating opioids may not be involved, locally released opioid mediators could still influence respiratory control.