The action of dopamine receptor antagonists on the secretory response of the cockroach salivary gland in vitro.
1. A study has been made of the potency of a number of dopamine antagonists to inhibit dopamine-induced secretion from the cockroach salivary gland in vitro. 2. Chlorpromazine (0.5-5 microM), SCH23390 (10-100 microM), haloperidol (10-100 microM) and metoclopramide (2 mM) competitively inhibited the secretory response to dopamine. In contrast (+/-)sulpiride (1-100 microM) and domperidone (1-100 microM) had no effect on either basal or dopamine-induced secretion. 3. Apparent dissociation constants (KDapp) were obtained using a 'three point assay'. The rank order of potency (KDapp in parentheses) was as follows: chlorpromazine (0.2 microM) greater than SCH23390 (2.2 microM) greater than haloperidol (17.5 microM) much greater than metoclopramide (1.2 mM). 4. It is concluded that the receptor mediating dopamine-induced secretion in the cockroach salivary gland is similar to the D1/DA1 dopamine receptor and distinct from the D2/DA2 receptor found in mammalian systems.
Evans
A M
AM
Department of Pharmacology, University of Edinburgh, U.K.
Green
K L
KL
D000818:Animals; D001552:Benzazepines / Q000494:pharmacology; D001667:Binding, Competitive; D002746:Chlorpromazine / Q000494:pharmacology; D003058:Cockroaches / Q000502:physiology*; D004294:Domperidone / Q000494:pharmacology; D004298:Dopamine / Q000494:pharmacology; D018492:Dopamine Antagonists; D006220:Haloperidol / Q000494:pharmacology; D008787:Metoclopramide / Q000494:pharmacology; D012469:Salivary Glands / Q000187:drug effects / Q000378:metabolism*; D013469:Sulpiride / Q000494:pharmacology
D001552:Benzazepines; D018492:Dopamine Antagonists; D004294:Domperidone; D013469:Sulpiride; D006220:Haloperidol; D008787:Metoclopramide; D002746:Chlorpromazine; D004298:Dopamine