P. A. M. van Zwieten

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In the present study we investigated the nature of the muscarinic receptors present in the hippocampus, sympathetic ganglia, atria and salivary glands of the rat. The heterogeneity of the muscarinic receptors was examined both in vivo and in radioligand binding experiments. To study whether the receptors present in the investigated tissues are indeed(More)
The central regulation of blood pressure and other cardiovascular parameters may involve the baroreceptor reflex are, including both adrenergic and serotonergic pathways, as well as amino acids, as neurotransmitters. Both adrenergic and serotonergic pathways have been recognized as targets for clinically relevant, centrally acting antihypertensives, such as(More)
Additional experimental evidence was obtained for an inhibitory function of prejunctional alpha 2-adrenoceptors and/or dopamine receptors located on noradrenergic neurons innervating the heart and resistance vessels of the pithed normotensive rat. Mixed alpha 2-adrenoceptor/dopamine receptor agonists, differing in selectivity towards either receptor type,(More)
The exact mechanism of action of beta blockers in migraine remains undetermined. An effect on the central nervous system (CNS) might be a factor. The evidence from the literature indicates that the anatomical and chemical targets for these drugs are present in the mammalian brain, that they readily penetrate the brain, and that they may modify CNS(More)
The discovery of postsynaptic alpha 2-adrenoreceptors with the drug specificities of presynaptic alpha 2-adrenoreceptors has contributed to a refinement of the classification of alpha-adrenoreceptors. postsynaptic alpha 2-adrenoreceptors have been identified by pharmacological means and with the aid of direct radioligand-receptor binding studies. The(More)
OBJECTIVE Forearm blood flow plethysmography is a widely accepted in vivo technique for pharmacologic and functional studies in peripheral resistance vessels and veins. Pharmacological effects on forearm blood flow (FBF) are usually expressed by means of dose-response relationships. This approach does not consider the influence of variations in FBF on the(More)
RU 24969 and 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) inhibited the specific binding of [3H]5-HT (2 nM) to rat brain membranes with shallow displacement curves. The displacement data were best fitted with a model of two independent, high and low affinity binding sites. Following addition of spiperone (1 microM) as a selective ligand for the(More)
The effects of Ca(2+)-entry blockade by nifedipine, K+ channel opening by cromakalim, and of omitting extracellular Ca2+ on the contractile response elicited by a supramaximum concentration of the "full" and selective alpha 1-adrenoceptor agonist phenylephrine (10(-4) M) were compared with those elicited by a supramaximal concentration of KCl (50 mM) in(More)
Clonidine was topically applied to the right eye of anesthetized cats. Unilateral administration induced a fall in intraocular pressure (IOP) in both eyes. This effect is not secondary to the slight fall in arterial blood pressure. Distribution experiments with 14C-clonidine revealed that only minor or negligible amounts of clonidine could be demonstrated(More)