The aim of this study was to identify the mechanisms that regulate dopamine release (DA(r)) by the hypoxic carotid body (CB) during development. CBs sampled from adult (n = 58) and 10-day-old (n = 53) rabbits were incubated for 1 h in a medium equilibrated with 8% O(2) in N(2) without or in the presence of the specific DA D(2) receptor antagonist domperidone, 0.01, 0.1 and 1 microM. DA and its major metabolite DOPAC were measured in the CB (DA(CB)) and in the medium (DA(r)) by HPLC+ED. In adults, each concentration of domperidone significantly decreased DA(CB) and increased DA(r), compared with control (p < 0.01). In contrast, in 10-day old, only the 1 microM domperidone concentration decreased DA(CB) and increased DA(r) compared with control (p < 0.001). The data show that domperidone increases CB DA(r) in response to hypoxia in a concentration- and age-dependent manner and suggest this response depends, in part, on the functional maturation of CB DA D(2) receptors.
Copyright 2001 S. Karger AG, Basel