Biomedical subjects

R Scatizzi

Publications and source records attributed to R Scatizzi.

11 recordsLinked to original sources

PubMed1996

A modified aortic multiple-ring preparation for functional studies.

A comparison is made of four rat aortic preparations, that is, single ring, spiral strip, zig-zag strip, and multiple-ring, on the basis of the responses to norepinephrine (NE) and acetylcholine (ACh). The single ring preparation was suitable under isometric, but not under isotonic conditions, because of the small isotonic tension which developed in response to the contractile agonist. The spiral and the zig-zag strips showed a discontinuity in the relaxant activity of the ACh, probably because of the removal, or not, of the endothelium from the preparation. The reproducibility of both contracturant and relaxing responses in the multiple-ring preparation makes this the most suitable of all four for the study of vasoactive drugs.

Acetylcholine↗

PubMed1996

Acetylcholine-induced bronchoconstriction modified by noise exposure in normal but not in sensitized guinea-pigs.

1. The acute (6h) exposure of guinea-pigs to white noise (110 dB) as a stress stimulus, reduced bronchial reactivity to acetylcholine (Ach) (3-1000 micrograms kg-1 i.v.) in anaesthetized animals. 2. The hyporesponsiveness to Ach in stressed animals was not confirmed in vitro on tracheal preparations (Ach 1 x 10(-9)-1 x 10(-4) g ml-1) and disappeared in vivo when the animals were sensitized with ovalbumin (OA, 100 mg kg-1 i.p. + 100 mg kg-1 s.c.). The hyporesponsiveness was also absent in ovalbumin sensitized guinea-pigs exposed to an aerosol of ovalbumin 60 min before testing with Ach. 3. In non-sensitized guinea-pigs, pretreatment with butoxamine (1 mg kg-1 i.v.) or with theophylline (25 mg kg-1 i.v.), completely abolished the effect of noise-exposure. In contrast, pretreatment with L-NG-nitro-arginine methyl ester (L-NAME, 10 mg kg-1 i.v.), alpha-chymotrypsin (2 U kg-1 i.v.) or with enprofylline (10 mg kg-1 i.v.), did not affect it. 4. In conclusion, our experiments reveal inhibitory mechanisms upon Ach-induced bronchoconstriction activated by a stress stimulus and this is absent in sensitized animals. These mechanisms seem to be linked to the adrenergic beta 2-receptors and a role for the purinergic system (via A-receptors) may also be present.

Acetylcholine↗

PubMed1995

Benzodiazepine agonists reverse the effects of noise exposure on central benzodiazepine receptors and cardiac responsiveness.

Rats were submitted to 110 dB white noise exposure for 1, and 6 hours and brain alpha 1, beta 1 and benzodiazepine receptor binding was evaluated with selective ligands. An increase in cerebral benzodiazepine receptor (CBR) concentration, without any significant change in affinity constant, occurred after the 6 h treatment; no change was observed in adrenergic receptor binding at any period of exposure. Both diazepam and clonazepam pre-treatment reversed the effects of noise on CBR binding, confirming a role of these receptors in the response to noise stress. Furthermore, these benzodiazepine agonists influenced the response of cardiac and aortic tissues, which are known to be changed by stress exposure. Diazepam and clonazepam pre-treatment protected cardiac tissue from the effects of 6h noise stress, and a potentiation of aortic responses was detected, although at different times of exposure. The differences between the responses of these peripheral tissues to benzodiazepine treatment suggest that the expression depends on the tissue examined and the period of exposure.

Animals↗

PubMed1995

Relaxing activity of two linear diterpenes from Cystoseira brachycarpa var. balearica on the contractions of intestinal preparations.

Eleganolone (1) and elegandiol (2), two linear diterpenes isolated from Cystoseira brachycarpa var. balearica, were tested on guinea-pig intestinal preparations. Both these compounds inhibited the contractile activities of acetylcholine (Ach) and histamine (Hist) on ileum musculature; the relative pIC50 values of eleganolone were found to be 4.60 +/- 0.03 and 4.84 +/- 0.20, respectively, while those of elegandiol were 4.71 +/- 0.18 and 5.18 +/- 0.01, respectively. Furthermore, 1 and 2 dose-dependently relaxed the same preparations precontracted with 300 microM BaCl2(pIC50 = 4.34 +/- 0.18 for 1 and pIC50 = 4.34 + 0.02 for 2) or with 60 mM KCl (pIC50 = 4.73 +/- 0.18 and 4.47 +/- 0.06, respectively). On colon smooth muscle, the diterpenes inhibited the spontaneous contractile tone and this effect was reversed by both methylene blue (3 x 10(-6) M) and haemoglobin (3 x 10(-6) M). Tetraethylammonium (TEA), furosemide, N omega-nitro-L-arginine methyl ester (L-NAME), indomethacin, alpha-chymotrypsin, and metoprolol were unable to block the eleganolone and elegandiol relaxing action on colonic musculature, but rather potentiated this response. On the contrary, the beta 2-blocker butoxamine partially inhibited the diterpenes activity. These results suggest that Cystoseira diterpenes act at a second messenger cyclase system rather than at a receptor level.

Animals↗

PubMed1995

Age-related changes in the noradrenergic pattern and receptor responses of the rat cardiovascular system after repeated microwave exposure.

In the present research the effect of repeated microwave exposure on the noradrenergic pattern by histofluorescence method and on receptor-mediated responses using alpha and beta agonists in myocardium and aorta of young-adult and aged rats was studied. Young-adult irradiated rats showed an increase in noradrenergic innervation more marked in myocardial tissue, while an increase in maximal response to the agonist was found only at aortic level. Aged stressed rats exhibited an increase in fluorescent fibres at atrial and aortic level, but in the atrial section this increase was found to be less evident than in young-adult animals. Functional data in aged rats revealed a more marked decrease in maximal response ratio (M.R.R.) of myocardial tissue than in young-adult rats, together with a noticeable decrease in maximal response at aortic level. These results indicate no direct correlation between morphological and functional data. Participation of both central and peripheral mechanisms is suggested.

Aging↗

PubMed1995

N(6) or N(9) substituted 2-phenyl-8-azaadenines: affinity for A1 adenosine receptors. VII.

The A1 activities shown respectively by N(6) or N(9) substituted 8-azaadenines were compared. At least in some cases, the biological results indicated the ability of the receptor to accept the exogenous molecule in various arrangements, and an attempt to rationalizing these arrangements was made by means of a model with two different molecular orientations.

Adenine↗

PubMed1994

Noradrenergic innervation and receptor responses of cardiovascular tissues from young and aged rats after acute microwave exposure.

Young and senescent rats were exposed to 2,450 GHz microwaves for 45' and the effects of this treatment on the noradrenergic pattern and beta-cardiac and alpha-aortic receptorial functions were evaluated. In young animals, an increase in noradrenergic innervation was observed, while no functional modification was shown. In aged rats the increase in fluorescent fibers was almost the same as that observed in young rats, but significant variations in functional responses were found. Both at atrial and ventricular levels responses to the beta-agonist isoprenaline were unmodified in their affinity indices, but showed a marked decrease in the maximal responses; by contrast the activity of noradrenaline on the aortic alpha-adrenoceptors showed a great increase in maximal response without changes in the pD2 values. These results suggest that the predominant effect of microwave exposure consists in an increase in the noradrenergic pattern, and this effect is not related to the functional modifications.

Aging↗

PubMed1994

Morphofunctional changes in the noradrenergic innervation of the rat cardiovascular system after varying duration of noise stress.

One, six and twelve hs of exposure to acoustic stress showed different influences on the noradrenergic pattern and receptor function of the rat atria and aorta. Moreover, the lipid content of the adrenal cortex and hepatic glycogen were histochemically evaluated in the same animals to correlate these observations with the previous results. The increase in exposure time induced a corresponding increase in sympathetic innervation, which was more evident at cardiac level. The functional results showed that the potency of the agonists on the alpha- and beta-adrenoceptors does not vary, with the exception of 6-h treatment, which affected beta-receptors. By contrast, the M.R.R. of beta-receptors proved to be modified in all treatments, suggesting that noise stress affected mainly postreceptorial mechanisms linked to beta-adrenoceptors rather than their density or affinity; no significant functional modifications were observed when alpha-receptors were considered.

Adrenal Cortex↗

PubMed1993

Conformationally restrained analogs of sympathomimetic catecholamines. Synthesis, conformational analysis, and adrenergic activity of isochroman derivatives.

In previous papers dealing with the study of the conformations and the biopharmacological activity of conformationally restrained analogs of sympathomimetic catecholamines (NE and ISO), proposals were advanced for the three-dimensional molecular models A, B, and C; these models provided information about the steric requirements for the direct activation of alpha 1, alpha 2,beta 1, and beta 2 adrenoceptors, respectively. The 1-(aminomethyl)-6,7-dihydroxyisochromans 11 and 12 and the 1-(aminomethyl)-5,6-dihydroxyisochromans 13 and 14 (1-AMDICs) are two different types of semirigid analogs of NE and ISO. The alpha 1, alpha 2, beta 1, and beta 2 adrenergic properties of the 1-AMDICs 11-14 were evaluated in vitro, both by radioligand binding assays and by functional tests on isolated preparations, and were compared with those of their parent compounds (NE and ISO). The results of a conformational study carried out by means of both 1H NMR spectrometry and theoretical calculations indicated that, in these 1-AMDICs, the presumed active groups (aryl moiety, amine nitrogen and benzylic ethereal oxygen) are in a spatial relationship corresponding to the one found for NE and ISO in their preferred conformations, which also proved to be the pharmacophoric conformation in the models A-C. By means of a comparison of the stereostructures of the 1-AMDICs 11-14 with their biopharmacological properties, it was possible to obtain a further definition of the model B with respect to the activation of the alpha 2 adrenoceptors; the superimposition of the 1-AMDICs 11 and 12 with the molecular model C made it possible to detect an area of the beta-adrenergic receptors which might hinder the fit of adrenergic drugs that are analogs of catecholamines with these receptors.

Animals↗

PubMed1993

Crude extracts and two linear diterpenes from Cystoseira balearica and their activity.

Crude extracts of Cystoseira balearica were submitted to pharmacological investigations. The chloroform-methanol residue caused relaxation of the rat aortic musculature and an inhibitory action on the guinea pig atria. The fractionation of this crude extract gave two active diterpenoids, eleganolone (1) and elegandiol (2), the latter has not previously been isolated from this alga. These pure components, never before tested, showed a higher activity when compared with the crude residue.

Animals↗

PubMed1992

Effects of subacute exposure to noise on the noradrenergic innervation of the cardiovascular system in young and aged rats: a morphofunctional study.

The effects of subacute noise stress on the noradrenergic pattern and receptor-mediated responses were examined in aorta and atria of young and aged rats. Noise exposure increased the density of noradrenergic fibres and responses to the beta-adrenergic agonist isoprenaline in the cardiac tissue of young animals. In aged rats, the stressing stimulus markedly increased the maximal response to the alpha-agonist on the aortic musculature; on the contrary, a reduced responsiveness to the beta-agonist was observed at the cardiac level, without any noteworthy changes in the noradrenergic pattern in comparison to aged controls. The present results indicate that subacute noise stress induces both morphological and functional modifications of the noradrenergic nervous system and also that after subacute noise stress, morphological changes do not necessarily correspond exactly to functional data; the latter show responses that are more widely differentiated than the morphological ones.

Aging↗