Biomedical subjects

G V Rossi

Publications and source records attributed to G V Rossi.

At least 19 recordsLinked to original sources

PubMed1982

Differential effects of LSD serotonin and l-tryptophan on visually evoked responses.

Alterations in photically-evoked cortical responses were assessed in immobilized artificially respired cats following intraraphe microinjections of LSD and serotonin (5-HT) and IV administration of LSD and l-tryptophan. Both systemic (10-100 micrograms/kg; N = 5) and intraraphe (0.25 microgram; N = 10) LSD significantly increased the amplitudes of the three primary components of the visual evoked response (VER). In contrast, the same VER components were significantly depressed following intraraphe 5-HT (30 micrograms; N = 4) and IV l-tryptophan (100 mg/kg; N = 6), a serotonin precursor that elevates raphe 5-HT levels. Intraraphe cinanserin (180 micrograms; 30 minute pretreatment) completely reversed LSD-induced enhancements in all three components (p less than 0.01). Depressions of VER following intraraphe 5-HT (30 micrograms) were also antagonized by cinanserin, although to lesser degree (p less than 0.05 for first 2 components only) than with LSD. The depressive effects of l-tryptophan (100 mg/kg) were unaffected by cinanserin. Modification of raphe neuronal activity can significantly alter photically evoked responses, and may explain the perceptual disturbances associated with LSD, i.e., depression of an area (raphe) normally inhibiting forebrain areas of the visual system.

Animals↗

PubMed1980

Brain-to-blood and saliva-to-blood mepivacaine ratios in rats.

Mepivacaine hydrochloride, 25 and 50 mg/kg sc (with sacrifice at 15 min) produced higher (p less than 0.005) drug levels in neonate (24--36-hr-old) rat brain and blood than in adult rat brain and blood; however, there was no significant difference in the brain-to-blood ratio of the drug between neonates and adults at either dose level. Intraarterial infusion of mepivacaine hydrochloride (20 micrograms/min) in adult rats resulted in measurable (GLC) mepivacaine base levels in pilocarpine-induced parotid salivary secretions collected throughout 30- and 45-min infusion periods. The saliva-to-blood ratios (+/- SEM) of mepivacaine base were 0.64 +/- 0.13 after a 30-min infusion and 2.13 +/- 0.48 after a 45-min infusion.

Aging↗

PubMed1979

Isolated lung strips of guinea pigs: responses to beta-adrenergic agonists and antagonists.

Isolated lung strips of guinea pigs were examined as an in vitro model for assessing the direct effect of beta-adrenergic drugs at the level of peripheral airways. Changes in intrinsic tone of thin strips of lung parenchyma were measured with an isometric force transducer. Isoproterenol, a nonselective beta-adrenergic agonist, and several beta-adrenergic agonists, soterenol, salbutamol, metaproterenol and ritodrine elicited a dose-related relaxation of lung strip. Responses to isoproterenol were antagonized by propranolol and the selective beta blocking agents butoxamine (beta2) and practolol (beta1). These results were compared to data obtained with the same compounds on isolated guinea pig atria. All agonists except ritodrine were full agonists in the lung strip whereas isoproterenol and metaproterenol were the only full agonists in the atrial preparation. In the atria, practolol was a more effective blocker of isoproterenol responses than butoxamine, and the reverse was true for the lung strip.

Adrenergic beta-Agonists↗

PubMed1977

Cardiovascular actions of three harmala alkaloids: harmine, harmaline, and harmalol.

Each of three harmala alkaloids, harmine, harmaline, and harmalol, decreased heart rate and increased pulse pressure, peak aortic flow, and myocardial contractile force in intact normotensive anesthetized dogs. Harmine reduced systemic arterial blood pressure and total peripheral vascular resistance; harmaline-evoked decreases were frequently followed by a secondary increase; and the effects of harmalol on these two parameters were inconsistent. A direct negative chronotropic effect of harmala alkaloids was suggested by observations of bradycardia in the isolated perfused rat heart and in the intact dog; neither vagotomy nor atropinization affected harmala alkaloid-induced bradycardia in the dog. Reduction in femoral vascular resistance by the alkaloids was not apparently due to activation of cholinergic, beta-adrenergic, or histamine (H1) receptors.

Alkaloids↗

PubMed1977

Measurement of prostaglandin E2 in an inflammatory exudate: effects of nonsteroidal anti-inflammatory agents.

A method was developed for extracting and measuring nanogram quantities of prostaglandin E2 (PGE2) from carrageenan-induced abscess in the rat. PGE2 concentration, quantitated by radioimmunoassay, was 42.5 and 92.9 ng/g of abscess in two studies. Anti-inflammatory activity, based on reduction in abscess weight, was observed with indomethacin, phenylbutazone, SC-19220 and A-22981; however, only indomethacin (10 mg/kg i.p.) significantly reduced PGE2 levels in the abscess tissue. Dose-related anti-inflammatory activity of indomethacin (1-10 mg/kg i.p.) was directly correlated with reductions of PGE2 content in the abscess. These data support the theory that the anti-inflammatory activity of indomethacin in the carrageenan abscess model involves inhibition of prostaglandin formation. Dose-related suppression of abscess formation by SC-19220 (7.5-30 mg/kg i.p.) was not related to changes in PGE2 levels at the inflammatory site, which suggests that the anti-inflammatory mechanism of SC-19220 is not mediated via inhibition of prostaglandin synthesis.

Abscess↗

PubMed1975

Tremor production by intracaudate injections of morphine.

Pronounced resting tremor was produced in unanesthetized cats by injecting morphine (25-110 mug) into the caudate nucleus. The effects of morphine were antagonized by intracaudate (i.c.) injections of nalorphine (81-263 mug). Tremor activity was also inhibited by i.c. injections of dopamine (61-145 mug), Ca2+ (24-40 mug), scopolamine (88-121 mug) and hemicholinium-3 (HC-3; 73-129 mug) while serotonin (125 mug) was ineffective. Tremor inhibition by HC-3 was reversed by i.c. doses of acetylcholine (15-30 mug) which were subthreshold for tremor production in the absence of morphine. Morphine (55-110 mug) further increased the intensity of ongoing tremor activity induced by physostigmine (111 mug i.c.) I.c. injections of nalorphine antagonized the motor effects of morphine without affecting physostigmime tremor. Tremor production by morphine is attributed to a reduction in dopamine function which allows cholinergic activity in the caudate nucleus to predominate.

Acetylcholine↗

PubMed1975