Plasma adenosine concentrations during adenosine-induced respiratory stimulation in man

Area of Science:

• Physiology
• Respiratory Control
• Neuropharmacology

Background:

• Adenosine, a nucleoside, is known to influence respiration.
• Its role in breathing control and the physiological relevance of its concentrations in vivo remain unclear.

Purpose of the Study:

• To investigate the effects of intravenous adenosine infusion on respiration in humans.
• To determine if adenosine concentrations achieved in vivo can modulate the ventilatory response to hypoxia.

Main Methods:

• Seven patients with arterial catheters received intravenous adenosine infusions.
• Minute ventilation and aortic arch plasma adenosine concentrations were measured.
• Ventilatory responses to hypoxia were assessed.

Main Results:

• Adenosine infusion significantly increased minute ventilation (from 5.5 to 10.9 L/min).
• Plasma adenosine concentrations increased from 0.07 to 1.2 microM.
• Some patients showed increased ventilation before detectable aortic adenosine increases, suggesting potential pulmonary effects.

Conclusions:

• Adenosine stimulates respiration at micromolar concentrations likely achieved in vivo.
• These findings support adenosine's role in mediating or modulating the ventilatory response to hypoxia.
• A potential intra-pulmonary effect of adenosine warrants further investigation.