A dopaminergic receptor modulates XXXX release from the cat adrenal gland.

@entity71661 @entity935 @entity1239 @entity5521 @entity3216 @entity1510 @entity3826 @entity1767 @entity2922 @entity2661 @entity1063
@entity1239 evokes the release of @entity2661 from perfused cat adrenal glands in a concentration-dependent manner, the median effective concentration for @entity1239 being 5 microM. Two 2 min pulses of 5 microM- @entity1239 , 40 min apart (S1 and S2) gave net @entity2922 outputs of 7.64 and 3.55 micrograms/8 min, respectively. The ratio S2/S1 in control glands was 0.5. Increasing concentrations of @entity3826 (1-10 microM) markedly inhibited @entity2922 release during the second @entity1239 pulse (S2). At 1 microM- @entity3826 , the release during S2 was significantly reduced to 16% of S1; with 10 microM- @entity3826 , the secretory response was reduced further to only 3% of S1, the ratio S2/S1 being 0.03. The presence of @entity1767 , @entity3216 or @entity71661 (each 0.5 microM) during S2, completely reversed the inhibition of @entity2922 release produced by @entity3826 . @entity1767 itself increased the nicotinic secretory response during S2; so, while the ratio S2/S1 was 0.5 in control conditions, this ratio increased significantly to 0.95 if @entity1767 (0.5 microM) was present during S2, suggesting that the presence of this dopaminergic antagonist removed a negative feed-back mechanism that inhibits @entity1239 -evoked @entity2922 release. If present during S2, @entity935 (1 microM) also markedly inhibited @entity2922 release evoked by @entity1239 ; this inhibition was again reversed by 0.5 microM- @entity1767 . Neither the opiate antagonist @entity1510 nor the alpha-adrenoceptor blocking agent @entity5521 (at concentrations of 0.5-5 microM) affected the inhibition by @entity3826 of the secretory response to @entity1239 . These data strongly suggest that the cat adrenal medulla chromaffin cell membrane contains a dopaminergic receptor which modulates the @entity2922 secretory process triggered by stimulation of the nicotinic cholinoceptor. The fact that @entity935 is released in measurable amounts, together with adrenaline and @entity1063 , from perfused cat adrenal glands in response to nicotinic stimulation (V. Ce  a, unpublished results), favours a role for this dopaminergic receptor in modulating @entity2922 release from the chromaffin cell.
