Effect of adenosine on isolated and superfused cat carotid body activity

Adenosine is known to increase carotid chemoreceptor discharge in vivo. Since adenosine has powerful vascular effects it is possible that this chemoexcitation is indirectly caused by changes in carotid body blood flow. To evaluate this possibility the effect of adenosine (0.02-2.0 mumol) was assessed on the chemoreceptor activity of the cat carotid bodies in vitro. All three doses of adenosine produced an increase in chemoreceptor discharge which reached its maximum within 10-20 s and subsequently returned to preinjection controls within 1 min. The chemoreceptor excitation caused by adenosine was dose-dependent. These results suggest that adenosine induces chemoexcitation without changes in blood pressure and blood flow.