DOPAMINE‐INDUCED AMYLASE SECRETION FROM GUINEA‐PIG SUBMANDIBULAR GLAND

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Abstract
1 The effects of dopamine, 5-hydroxydopamine (5-OHDA) and noradrenaline on amylase secretion from the guinea-pig submandibular gland were investigated under in vitro conditions. 2 All three amines greatly enhanced amylase secretion. Blockade of dopamine β-hydroxylase did not inhibit the response to dopamine. 3 Noradrenaline and dopamine stimulated amylase release from salivary glands of reserpine-treated animals, whereas 5-OHDA had no stimulatory effect on secretion in guinea-pigs pretreated with reserpine. 4 Haloperidol completely inhibited dopamine-induced enzyme discharge, but did not affect noradrenaline-initiated secretion. 5 Apomorphine caused a slight enzyme release by itself; it diminished the dopamine secretory effect, but did not modify that of noradrenaline. 6 Pimozide and fluspirilene attenuated the dopamine-induced enzyme discharge, but compared with haloperidol they were less effective. 7 It is concluded that dopamine exerts a secretagogic action different from that of noradrenaline. The possible presence of a specific dopamine receptor in salivary glands is discussed.