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Biomedical subjects

S Lecchini

Publications and source records attributed to S Lecchini.

At least 91 records · Page 5Linked to original sources
PubMed1981

Hyoscine-resistant peristalsis in guinea-pig ileum.

The effect of hyoscine on the peristaltic activity of the proximal and distal ileum of the guinea-pig was studied. Hyoscine strongly impaired peristalsis as indicated by the elevation of the threshold pressure and by the increased number of incomplete peristalses and blockades. Functional activity of the circular musculature was more markedly impaired. However, particularly in the distal ileum, complete peristalses occurred even after 70 min exposure to hyoscine at a concentration of 10(-6) g/ml. A tenfold increase in hyoscine concentration failed to produce further impairment of peristaltic activity and of the oral reflex contraction. The activity which remained in the presence of hyoscine was blocked by methysergide and by d-tubocurarine. The hypothesis is advanced that once the muscarinic receptors have been blocked, increased radial stretch of the circular coat results in activation of a separate, tetrodotoxin sensitive, excitatory nervous pathway, which is sufficient to maintain a discrete degree of peristaltic activity.

Animals↗
PubMed1980

Interaction between phenytoin and valproic acid: plasma protein binding and metabolic effects.

The effect of sodium valproate (400 mg three times daily) on the disposition kinetics of intravenous phenytoin (250 mg) was investigated in seven normal subjects. After valproate, the free (unbound) fraction of phenytoin in serum rose from 9.6 +/- 0.9% (SD) to 15.6 +/- 1.4% on average (p < 0.001). The effect was associated with an increase in systemic clearance and apparent volume of distribution of total drug. There was a strong positive correlation between percent increment in each of these parameters and percent increment in unbound drug in serum. Free phenytoin concentration in serum and phenytoin concentration in saliva increased during valproate administration. As a result, both the clearance and the apparent volume of distribution of free drug were reduced. There was an increase in the renal excretion of unchanged phenytoin during valproate administration, but the effect was too small to have an appreciable influence on the overall clearance of the drug. There were no consistent changes in the excretion of the major metabolite 5, p-hydroxyphenyl, 5-phenyl, hydantoin (pHPPH), in the urine. These results suggest that valproic acid may have two separate and opposing effects on phenytoin disposition: (1) displacing phenytoin from plasma protein binding sites, thereby enhancing the systemic clearance of total drug, and (2) inhibiting phenytoin metabolism, thereby increasing the concentration of free drug in the serum.

Adult↗
PubMed1980

Effects of metopimazine on gastro-intestinal and biliary tract smooth muscle in vitro.

The effects of the phenothiazine derivative metopimazine on the spontaneous or induced activities of guinea-pig isolated stomach and of the rabbit biliary and intestinal tracts were studied. A predominant inhibitory effect was observed except for the circular muscle layers of the duodenum and colon where activation appeared. Evidence from in vitro experiments suggest that metopimazine exerts an inhibitory action partly through a direct effect on smooth muscle cells and partly by reducing stimulated acetylcholine release (at least in the stomach). Finally the involvement of a non-adrenergic, non-cholinergic inhibitory system is postulated.

Acetylcholine↗
PubMed1979

Modification of phenytoin clearance by valproic acid in normal subjects.

1 The effect of valproic acid on the distribution and elimination kinetics of intravenously administered phenytoin has been investigated in eight normal volunteers. 2 In each of the subjects studied the volume of distribution of phenytoin increased significantly during treatment with sodium valproate (1200 mg daily for 7 days). 3 Phenytoin clearance was markedly increased in presence of valproic acid as compared to control values (0.52 +/- 0.17 v 0.38 +/- 0.11 ml min-1 kg-1 respectively, P less than 0.02). 4 It is suggested that the increase of the volume of distribution and of the serum clearance are secondary to displacement of phenytoin from plasma protein binding sites by valproic acid.

Adult↗
PubMed1977

Effects of pentazocine on the intestine and biliary tract of the rabbit in vitro.

Pentazocine impairs peristaltic activity and relaxes longitudinal muscle in the colon and in the ileum. The circular coat is excited in the colon, while in the ileum pentazocine exhibits both excitatory and inhibitory effects depending on the concentration employed. Pentazocine does not exert a spasmogenic effect in the smooth muscle of terminal bile duct but instead reduces the electrically-induced contraction. The effect of pentazocine does not seem to involve endogenous acetylcholine or catecholamine release.

Acetylcholine↗