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Biomedical subjects

F Amenta

Publications and source records attributed to F Amenta.

At least 253 records · Page 14Linked to original sources
PubMed1984

Age-associated decrease of dopamine-sensitive adenylate cyclase in rabbit renal artery.

Using renal arteries from young (6 months), mature (18 months) and old (70 months) rabbits, the effect of dopamine on 3',5'-cyclic adenosine monophosphate (cAMP) generation was studied. No significant differences in basal adenylate cyclase values were found in homogenates of renal artery from young, mature or old rabbits. The protein content of the renal artery was also unchanged during the lifespan. Dopamine stimulated the production of cAMP. The stimulatory effect of dopamine was similar in the renal artery of young and mature rabbits but was lower by about 40% in old rabbits. The present results led us to hypothesize an impairment of the peripheral dopaminergic system in old age similar to that described for the central dopaminergic system.

Adenylyl Cyclases↗
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

Changes of [3H]spiroperidol binding in the renal artery of aged rabbits.

Using mature (12 months), old (70 months) rabbits and 3H-labeled spiroperidol, the characteristics of renal artery dopamine receptors were studied. In old age the dissociation constant of [3H]spiroperidol was unchanged, while maximum specific binding was reduced more than 45%. The present data seem to indicate an impairment of peripheral dopaminergic function in ageing.

Aging↗
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↗
PubMed1984

Regional distribution of cholinergic nerves in rat parietal pericardium.

The innervation pattern of parietal pericardium was studied in normal as well as chemically sympathectomized rats using the cholinesterase histochemical method. The existence of important regional variations in the distribution of cholinergic nerves within various portions of parietal pericardium studied was observed. The atria appear more richly innervated than ventricles, while the innervation of atria is characterized by the existence of thin and thick cholinergic nerve fibers not organized in plexuses and of elbow-shaped acetylcholinesterase cholinergic nerve fibers. Small blood vessels and islands of adipocytes receive a cholinergic innervation as well. The chemical sympathectomy does not alter the pattern of stained cholinergic nerve fibers. A possible afferent significance of the atrial innervation is discussed.

Acetylcholinesterase↗
PubMed1983

Dopamine-sensitive adenylate cyclase in rabbit renal artery.

The effect of dopamine on 3',5'-cyclic adenosine monophosphate (cAMP) generation in the rabbit renal artery was studied. Dopamine added to homogenates of rabbit renal artery increased the concentration of cAMP. The stimulation of cAMP levels elicited by dopamine was remarkably reduced by the dopamine receptor antagonists fluphenazine and haloperidol, but it was unaffected by the ergot-like dopaminergic agonist bromocriptine. These findings appear to indicate that the effects of dopamine on rabbit renal artery are mediated through a D1 receptor.

Adenylyl Cyclases↗
PubMed1983

Stimulatory effect of beta-estradiol treatment on GABA-degradative enzymes within rat cerebellar cortex.

The influence of neonatal beta-estradiol treatment on the development of GABA-degradative enzymes (GABA transaminase and succinic semialdehyde dehydrogenase) within rat cerebellar cortex has been studied using a semiquantitative histochemical technique. Both enzymatic activities were stimulated following beta-estradiol treatment. In particular, the granule and Purkinje cells were the most influenced cerebellar components. The findings seem to suggest that granule and Purkinje cells may represent the principal target of the cerebellar cortex for sex hormones.

4-Aminobutyrate Transaminase↗
PubMed1983

Detection of neuronal uptake of [3H]dopamine in the rabbit celiac artery.

[3H]Dopamine ([3H]DA) is specifically taken up by slices of rabbit celiac artery. Corticosterone, a selective inhibitor of extraneuronal uptake processes, was found to reduce the uptake of the labelled catecholamine by about 30%. Desimipramine, an inhibitor of uptake processes in noradrenergic neurons, caused a decrease of [3H]DA uptake of about 35%. Benztropine, an inhibitor of uptake processes in dopaminergic neurons reduced [3H]DA uptake by about 30%. The neuronal uptake of [3H]DA was completely inhibited by chemical sympathectomy or by simultaneous incubation of the slices with desimipramine and benztropine. Norepinephrine had a competitive effect on [3H]DA uptake and benztropine inhibited [3H]norepinephrine uptake by 32%. The results are consistent with the existence of a double noradrenergic and dopaminergic innervation of the rabbit celiac artery.

Animals↗
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↗
PubMed1983

The autonomic innervation of the vasa nervorum.

Using catecholamine fluorescence and histochemical cholinesterase staining combined with quantitative image analysis a direct autonomic innervation of arteries, arterioles, venules, veins and arterio-venous anastomoses within peripheral nerves was demonstrated in normal as well as in chemically sympathectomized rats. The adrenergic nerves carry varicosities and were more diffused than acetylcholinesterase-containing nerves; the arteries and the arterio -venous anastomoses were more richly innervated. The findings that acetylcholinesterase-positive nerve fibres were unalterated by chemical sympathectomy and were revealed by short incubation times are indicative of a true cholinergic, and probably parasympathetic, innervation of the vasa nervorum. The possible importance of the autonomic innervation of the vasa nervorum in the pathogenesis of some diseases of peripheral nerves is discussed.

Acetylcholine↗
PubMed1983

The autonomic innervation of the human greater saphenous vein.

The existence of a double catecholaminergic and cholinergic innervation was demonstrated in the human greater saphenous vein. Catecholamine-containing nerve fibres are organized in a network-like plexus localized at the adventitial-medial border. Acetylcholinesterase-containing nerve fibres are arranged in a plexus found at the adventitial-medial border as well. Catecholamine and acetylcholinesterase-containing nerve fibres, while localized in close apposition since they occupy the same portion of the vein, represent two distinct and independent populations of nerve fibres coming likely from the sympathetic and parasympathetic sections of the autonomic nervous system respectively. Our findings demonstrating a close relationship between catecholaminergic and cholinergic nerve fibres within the wall of the human greater saphenous vein offer morphological support to physiological and pharmacological results reported in the literature of a presynaptic control exerted by cholinergic nerves on norepinephrine release at the level of the saphenous vein.

Acetylcholinesterase↗
PubMed1983

The cholinergic innervation of human pancreatic islets.

The cholinergic innervation of pancreatic islets was investigated in the human using operatory samples. In order to analyze the nature of stained cholinergic nerve fibers some specimens were incubated in a solution containing 6-hydroxydopamine (6-HDA) to obtain a selective degeneration of adrenergic nerves. Cholinergic nerve fibers are present in human pancreatic islets, and appear to be organized in an external peri-insular plexus. Some nerve fibers from the peri-insular plexus enter the islets and seem to innervate directly various types of endocrine insular elements. The 6-HDA treatment does not alter the distribution pattern of cholinergic nerve fibers within pancreatic islets.

Acetylcholinesterase↗
PubMed1983

Cholinergic innervation of the human pulmonary circulation.

The cholinergic innervation of the pulmonary circulation was studied in man. Both extra- and intrapulmonary branches of the pulmonary artery and vein are provided with a cholinergic of the vein. In the main branches of the pulmonary vessels, the existence of two nerve plexuses, a superficial and a deep one, was observed. The superficial plexus is localized in the outer adventitial layer while the deeper plexus is localized in the adventitial-medial transitional zone. In smaller arteries and veins, the existence of a single plexus (adventitial-medial) was observed. In some specimens, the presence of diffuse masses of acetylcholinesterase (AChE)-positive material or elbow-shaped AChE-positive formations was observed. The nature of these formations as well as the possible functional role of a cholinergic system in the pulmonary circulation are discussed.

Acetylcholinesterase↗
PubMed1983

Autonomic innervation of rat portal vein.

The innervation of the rat portal vein was studied using the catecholamine fluorescence, cholinesterase and quinacrine histochemical methods. The rat portal vein, while provided with an adrenergic and cholinergic innervation, do not shows nerve fibers like structures with a selective affinity for quinacrine. A knowledge of the pattern of innervation of portal vein in various mammalian species may provide useful information to evaluate data obtained by the use of physiological and pharmacological methods.

Animals↗
PubMed1982

Indoleaminergic innervation of rat choroid plexus: a fluorescence histochemical study.

Using a fluorescence histochemical technique we found that the precursor of serotonin, 5-hydroxytryptophan (5-HTP), is taken up by a population of nerve fiber-like structures, indoleaminergic in nature since selectively destroyed by the neurotoxin 6-hydroxytryptamine, within rat choroid plexus. Nerve fiber-like structures are localized within the wall of choroid blood vessels. More infrequently nerve fibers end in the stroma or in close relation to epithelial cells of the plexus. The electrolytic lesioning of raphe nuclei causes the disappearance of 5-HTP fluorescence, suggesting that these nerve fibers originate from raphe nuclei. These results suggest a direct influence of indoleaminergic pathways originating from the brainstem on the blood flow through choroid plexus as well as on the production of cerebrospinal fluid.

5-Hydroxytryptophan↗