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Biomedical subjects

M De Rossi

Publications and source records attributed to M De Rossi.

28 records · Page 2Linked to original sources
PubMed1985

Histoautoradiographic localization of (-)-3H-dihydroalprenolol in rabbit aorta.

The distribution pattern of (-)-3H-dihydroalprenolol (3H-DHA) binding sites within the thoracic and abdominal aorta was studied using a histoautoradiographic technique. Frozen sections of rabbit aorta were incubated with 3H-DHA in the presence or absence of 1 mumol/l (-)-propranolol and of increasing concentrations of various adrenergic agents. After washing, the same secretions were placed in scintillation vials and counted to evaluate the pharmacological characteristics of 3H-DHA binding or processed for histoautoradiography. 3H-DHA was bound by sections of the rabbit aorta in a manner consistent with the presence of beta-adrenoceptors. The binding was reversible, saturable and of high affinity, with a dissociation constant Kd of 1.0 nmol/l and a maximum binding capacity Bmax of 17 fmol/mg tissue (wet weight). It was inhibited only by beta-adrenoceptor blocking drugs. Histoautoradiographic studies revealed that beta-adrenoceptors are located primarily in the media and then in the intima. The lowest density of 3H-DHA was found in the adventitia. The distribution pattern of beta-adrenoceptors in the media suggests the possible existence of two groups of beta-adrenoceptors within this layer of the aorta. The first group was found in the outer portions of the media and may be controlled by the adrenergic nerves that supply the artery. The second group was found in the portions of the media closest to the intima and is likely under the control of catecholamines coming from the lumen of the aorta.

Alprenolol↗
PubMed1984

Dopamine-sensitive cAMP generating system in rat extracerebral arteries.

The effect of dopamine (DA) on the 3',5'-cyclic adenosine monophosphate (cAMP) generating system in rat extracerebral arteries was studied in order to identify DA receptors. The carotis interna and the basilar artery as well as the arteries of the circle of Willis were homogenized and centrifuged. This extracellular arterial preparation was used for studying the effect of DA, norepinephrine and of drugs interfering with alpha- and beta-adrenergic as well as with dopaminergic receptors on cAMP production. DA increased the concentration of cAMP. The DA-elicited increase of cAMP levels was inhibited by dopamine receptor blocking agents (phenothiazine derivatives and butyrophenones) but unaffected by alpha- or beta-adrenoceptor blocking drugs or by the ergot-like DA agonist bromocriptine, or by sulpiride. The findings appear to be indicative of the existence of only D1 receptors within the blood vessels studied.

Animals↗
PubMed1984

3H-spiroperidol binding sites in the rabbit superior mesenteric artery. A histoautoradiographic study.

The distribution of 3H-spiroperidol binding sites within rabbit superior mesenteric artery was studied in normal as well as 6-hydroxydopamine (6-OHDA) sympathectomized animals using a histoautoradiographic technique. The labelled drug was located in the three layers of the artery (adventitia, media and intima), with the greater density in the media. In the adventitia the radiolabelled drug was located at the level of fibrous and connective cells. In the media 3H-spiroperidol was bound by smooth muscle cells and is found in the cellular membrane of the same cells. 6-OHDA administration causes an increase in the number of 3H-spiroperidol binding sites in the adventitia and as well as a 20-25% increase in the media. The possible existence of a direct dopaminergic innervation of the superior mesenteric artery is discussed.

Animals↗
PubMed1984

Localization of dopamine receptors in the rabbit renal artery: a histoautoradiographic study.

The localization of dopamine receptors within rabbit renal artery was studied using 3H-spiroperidol as a label for dopamine receptors and a histoautoradiographic technique. Preliminary radioreceptor binding studies showed that 3H-spiroperidol was bound to sections of renal artery in a manner consistent with the existence of dopamine receptors. In fact the binding was found to be saturable, stereospecific and of high affinity, with a Bmax approximately of 158.3 fmol/mg protein and a Kd of 13.5 nmol/l. The microscopic examination of sections processed for the histoautoradiographic demonstration of 3'-spiroperidol binding sites showed that the distribution of dopamine receptors in the renal artery was widespread. The highest concentration of dopamine receptors was found primarily in the smooth muscle cells of the media and then, in the following order, in endothelial cells of the intima and in fibrous and connective cells of the adventitia. The direct demonstration of dopamine receptors in the media of rabbit renal artery strongly supports the hypothesis that these receptors may be involved in the relaxation of the artery caused by infusion or application of dopamine.

Animals↗
PubMed1984

Dopamine-sensitive adenylate-cyclase in rabbit superior mesenteric artery.

The effect of dopamine on 3'-5'-cyclic adenosine monophosphate (cAMP) generation in the rabbit superior mesenteric artery was studied in order to identify dopamine receptors. Dopamine added to homogenates of superior mesenteric artery increased the concentration of cAMP. The stimulation of cAMP levels elicited by dopamine was unaffected by alpha or beta-adrenergic receptor blocking agents but was remarkably reduced by the dopamine receptor blocking agents fluphenazine and haloperidol. The findings appear to indicate that the effects of dopamine on rabbit superior mesenteric artery are mediated through activation of the adenylate-cyclase cAMP system.

Adenylyl Cyclases↗
PubMed1983

Beta-adrenoceptors in the rat kidney. Immunohistochemical study.

The direct histochemical detection of beta-blocker binding sites was studied in sections of rat kidney using an immunohistochemical technique developed in our laboratory. Frozen sections of rat kidney were incubated in a solution of (-)alprenolol, washed, exposed to fluorescent (-)alprenolol antibodies (FAA) and then observed at a fluorescence microscope. Strong fluorescence was found within the wall of renal artery and vein, but primarly in the artery. At the level of blood vessels (-)alprenolol binding sites were located chiefly in the media and in the intima. The renal glomerulus, the loop of Henle and collecting tubules appear to be free of any fluorescence. Consequently they do not have beta-adrenoceptors. On the contrary, the glomerular afferent and afferent arterioles, the cellular elements of the juxtaglomerular apparatus, proximal and distal convoluted tubules, are rich in (-)alprenolol binding sites. At higher magnifications the immunoreactivity appears to be located in the basal membrane of cellular elements which indicates that (-)alprenolol binding sites are membrane receptors. The direct immunohistochemical detection of beta-blocker binding sites in the kidney may offer useful information concerning the site of action of beta-blockers at the level of an important target organ for this class of drugs.

Animals↗
PubMedDate not supplied

[Exposure to crystalline silica in the air during renovation of residential buildings].

Exposure to respirable cristalline silica dust during construction activities can cause silicosis and, in accordance with International Agency for Research on Cancer (IARC), even lung cancer. Among the different facets of construction, residential buildings are of particular interest because the lack of exposure data for workers employed. In this sector a dry sand-blasting of brick ceiling and renewal activities has been investigated. The survey has been carried out in a civil dwelling and 58 samples have been collected using the SKC aluminium cyclone and Door-Oliver plastic cyclone at flow-rate 2.2-1.7 l/min. The respirable dust samples were analysed by x-ray diffraction using NIOSH Method 7500. Even if the results of this study should be considered preliminary, they showed SLC respirable concentrations even many time above TLV-TWA during a sand-blasting activities and some times also during the other activities. Awaiting the correct classification from European Community, it would be desiderable that the workers would had appropriate information and prevention on the specific risks associated to the dust in the construction activities.

Air Pollution, Indoor↗
PubMedDate not supplied

Effect of dopamine on the cyclic adenosine monophosphate generating system in the rabbit internal carotid and middle cerebral artery.

The effect of in vitro addition of dopamine on the 3'-5'-cyclic adenosine monophosphate (cAMP) generating system of rabbit internal carotid and middle cerebral artery was studied. Dopamine increased cAMP levels in a dose-dependent manner in both arteries. The DA1-receptor antagonist SCH 23390 decreased the dopamine-elicited cAMP increase. On the contrary, the DA2-receptor antagonist L-sulpiride caused an increase in dopamine-dependent cAMP levels. The simultaneous addition of SCH 23390 and of L-sulpiride abolished any effect of dopamine on cAMP content. The DA2-receptor agonists bromocriptine and co-dergocrine decreased cAMP levels. The above findings indicate the existence in the rabbit internal carotid and middle cerebral artery of 2 types of dopamine receptors mediating respectively, the increase (DA1-effect) and the decrease (DA2-effect) of cAMP levels.

Animals↗
PubMedDate not supplied

Autoradiographic localization of the dopaminergic agonist 3H-dihydroergotoxine within the male reproductive system.

By the use of combined radioreceptor binding and autoradiographic techniques, we analyzed the anatomical localization of the dopaminergic agonist 3H-dihydroergotoxine in tissue sections of rat male sex organs. The drug was bound by smooth muscle cells of the deferent duct, seminal vesicles and prostate gland as well as by the glandular tissue of seminal vesicles and prostate gland. These data allow us to hypothesize that the effect of dopaminergic agonists on male sexual function may be due, at least in part, to a direct interaction with dopamine receptors present in the reproductive organs.

Animals↗