Search results for "Dopamine Antagonists"
showing 4 items of 44 documents
D1 receptors play a major role in the dopamine modulation of mouse ileum contractility
2010
Since the role of dopamine in the bowel motility is far from being clear, our aim was to analyse pharmacologically the effects of dopamine on mouse ileum contractility. Contractile activity of mouse ileum was examined in vitro as changes in isometric tension. Dopamine caused a concentration-dependent reduction of the spontaneous contraction amplitude of ileal muscle up to their complete disappearance. SCH-23390, D1 receptor antagonist, which per se increased basal tone and amplitude of spontaneous contractions, antagonized the responses to dopamine, whilst sulpiride or domperidone, D2 receptor antagonists, were without effects. The application of both D1 and D2 antagonists had additive effe…
Effects of dopamine in isolated rat colon strips.
2005
The aim of the present work is to investigate the effects of dopamine on isolated rat colon strips, and whether dopamine receptors are involved in these effects. Experiments on spontaneous motility and under potassium contraction were performed with dopamine and isoprenaline, both in the absence and presence of antagonists (distal colon strips, isotonic recording, Tyrode solution, 31 °C, 1 g of resting tension). At higher concentration (10–4mol/L), dopamine abolished spontaneous motility of the rat colon and this effect was not modified by antagonists. In isolated rat colon strips that were depolarized with potassium, dopamine produced concentration-dependent relaxation, without significant…
D2-receptor imaging with [123I]IBZM and Single Photon Emission Tomography in psychiatry: a survey of current status
1995
D2-dopamine receptors can be visualized in the human brain in vivo by Single Photon Emission Tomography (SPECT) and the radiolabeled benzamide [123I]IBZM. The present paper reviews the current status of this type of functional brain imaging with respect to basic methodological aspects, data analysis and quantification. The results from published clinical studies in different psychiatric patient populations and normal controls with [123I]IBZM are reviewed. [123I]IBZM-SPECT is a powerful tool for the investigation of D2-dopamine receptor status in psychiatric disorders, different types of drug treatment as well as therapeutic and side effects of pharmacologic agents. However, there still is a…
D2-dopamine receptor blockade modulates temporal resolution in goldfish.
2002
A possible effect of dopamine on the temporal resolution of goldfish was investigated in a behavioral, two-alternative, forced-choice procedure. Flicker fusion frequency (FFF) was measured before and after bilateral intravitreal injections of D1- or D2-dopamine receptor (D1-/D2-R) antagonists, or after depletion of retinal dopamine by bilateral intravitreal injections of the dopaminergic neurotoxin 6-hydroxydopamine (6-OHDA). Prior to drug injections, fish achieved FFFs of 33–39 Hz. A D1-R antagonist, SCH 23390, reduced FFF by about 12% (P > 0.1), whereas a D2 antagonist, sulpiride, reduced the relative FFF by 25% (P < 0.03). Depletion of retinal dopamine with 6-OHDA induced a gradual…