FEEDBACK INHIBITION OF CA-2+ CURRENTS BY DOPAMINE IN GLOMUS CELLS OF THE CAROTID-BODY

The effect of dopamine on the voltage‐dependent ionic channels of enzymatically dispersed glomus cells from rabbit carotid bodies was studied. Whole‐cell currents were recorded on isolation with patch electrodes and dopamine applied to the bath solution. Dopamine at nanomolar concentrations produced a reversible attenuation of the calcium current whereas sodium and potassium currents remained unaltered. Dopamine inhibition of Ca2+ current was observed in all cells tested (n= 48) and at a saturating concentration (1μM) the average reduction was of 40 ± 6.5% (n= 8). The effect of dopamine was probably caused by a decrease in the number of channels activatable on depolarization since it did not modify the voltage‐dependent parameters of the current. These results indicate that dopamine, which is the major transmitter secreted by glomus cells, regulates further transmitter release by feedback inhibition of Ca2+ channels. Copyright © 1990, Wiley Blackwell. All rights reserved