Differences in dopamine- and noradrenaline-induced amylase release from the rat parotid gland.
The effects of dopamine and noradrenaline on amylase secretion from rat parotid gland were studied in a batch incubation system. Dopamine effectively caused amylase secretion but the concentration-response curve was shifted to the right in reserpinized animals, suggesting a minor indirect component in the action of dopamine. The noradrenaline-evoked secretion was the same in reserpinized glands as in the controls. Bromocriptine, a dopamine receptor agonist, was without effect on amylase secretion. The dopamine receptor antagonists pimozide, chlorpromazine, haloperidol and droperidol as well as SKF 38393 all effectively inhibited dopamine-induced amylase secretion without affecting the enzyme release caused by noradrenaline. The D-2 antagonist sulpiride was without effect on both dopamine- and noradrenaline-stimulated secretion. The dopamine-induced secretion was also significantly blocked by the non-selective beta-blocker propranolol as well as by beta 1- and beta 2-selective antagonists. Several alpha-antagonists were all partial blockers of dopamine-stimulated amylase secretion. In contrast, the noradrenaline-evoked amylase release was exclusively abolished by propranolol and beta 1-selective antagonists. The results suggest that the dopamine- and noradrenaline-induced amylase secretion are activated via different receptor systems, and that dopamine stimulation is mainly a postsynaptic D-1 effect and only to a minor extent due to presynaptic interaction.
Sundström
S
S
Carlsöö
B
B
Danielsson
A
A
Henriksson
R
R
D000681:Amylases / Q000378:metabolism*; D000818:Animals; D004298:Dopamine / Q000494:pharmacology*; D005260:Female; D009638:Norepinephrine / Q000494:pharmacology*; D010306:Parotid Gland / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D011942:Receptors, Adrenergic, alpha / Q000502:physiology; D011943:Receptors, Adrenergic, beta / Q000502:physiology; D011954:Receptors, Dopamine / Q000502:physiology; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2; D013268:Stimulation, Chemical
D011942:Receptors, Adrenergic, alpha; D011943:Receptors, Adrenergic, beta; D011954:Receptors, Dopamine; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2; D000681:Amylases; D004298:Dopamine; D009638:Norepinephrine