Age-dependent effect of domperidone on dopamine release by the hypoxic carotid body in the rabbit

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 s ampled from adult (n = 58) and 10-day-old (n = 53) rabbits were incubated f or 1 h in a medium equilibrated with 8% O-2 in N-2 without or in the presen ce of the specific DA D-2 receptor antagonist domperidone, 0.01, 0.1 and 1 muM. DA and its major metabolite DOPAC were measured in the CB (DA(CB)) and in the medium (DA,) by HPLC+ED. In adults, each concentration of domperido ne significantly decreased DACB and increased DAr, compared with control (p < 0.01). In contrast, in 10-day old, only the 1 muM domperidone concentrat ion decreased DACB and increased DA, compared with control (p < 0.001). The data show that domperidone increases CB DA, in response to hypoxia in a co ncentration- and age-dependent manner and suggest this response depends, in part, on the functional maturation of CB DA D2 receptors. Copyright (C) 20 01 S. Karger AG, Basel.