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Biomedical subjects

G Bertaccini

Publications and source records attributed to G Bertaccini.

At least 145 records · Page 8Linked to original sources
PubMed1982

[Pharmacological effects of the combination of a spasmolytic (otilonium) with a benzodiazepine (diazepam)].

The pharmacological effects of an association represented by a myolitic agent (otilonium bromide) and a benzodiazepine (diazepam) were investigated on different in vitro preparations and on one in vivo test. In the isolated preparations both drugs administered alone showed a remarkable inhibitory effect on the motility of different areas of the digestive system both spontaneous and evoked by different stimulatory agents. Association of the two compounds gave rise to additive effects or actually to a potentiating effect according to the different tissues and animal species. Negative interference was never observed. The same was true also in the in vivo preparation ("in situ" rat pylorus). The significance and the importance of these observations are discussed also in the light of the relevant clinical implications.

Acetylcholine↗
PubMed1981

Effect of some new Histamine H2-receptor antagonists on the guinea-pig papillary muscle.

Several histamine H2-receptor antagonists (cimetidine, ranitidine, oxmetadine and tiotidine) were tested for their activity on the papillary muscle of the guinea pig stimulated by histamine. All of the compounds exerted a competitive antagonism against histamine the order of potency being tiotidine greater than oxmetidine greater than ranitidine greater than cimetidine. Oxmetidine was the only drug which at high concentrations (10-6 M) decreased in maximum response of histamine probably because of non specific effects of the molecule already described in the literature. As it was expected, the H1-receptor antagonist, mepyramine, exerted a non-competitive antagonism.

Animals↗
PubMed1981

The effect of bombesin on gastric emptying of solids in man.

Intravenous infusion of bombesin (5 ng.kg(-1). min(-1) significantly delayed gastric emptying of solids in man. The gastrin response to meal increased following administration of the peptide; however no correlation was found between the difference in gastrin response (to meal alone and to meal plus bombesin) and the degree of delay in emptying. In addition the behavior of intragastric pH after eating was not modified by bombesin infusion. All of these data suggest a direct effect of the peptide on gastric emptying, which was probably connected with the strong contraction of the antrum and pylorus observed in this and in previous investigations.

Adult↗
PubMed1981

Effect of impromidine (SK&F 92676) on the isolated papillary muscle of the guinea-pig.

Impromidine was found to have a positive inotropic effect on the isolated papillary muscle from the guinea-pig. The dose-response curve to impromidine was shifted to the right by cimetidine and ranitidine. Impromidine was 35 times more potent than histamine but with a maximal response of only 81% that obtained with histamine. This difference, which was statistically significant (P < 0.005), suggested that impromidine acts as a partial agonist at the histamine H2-receptors of the papillary muscle as has been observed in other tissues.

Animals↗
PubMed1981

Effect of substance P and its natural analogues on gastric emptying of the conscious rat.

1 Substance P and its natural analogues were tested for their effect on gastric emptying in the rat. 2 Substance P and kassinin were virtually inactive even at the maximum dose tests. 3 The other tachykinins significantly delayed gastric emptying their effect being quite remarkable with 100 micrograms/kg. The lowest doses (30 microgram/kg) caused a slight and non-significant increase in emptying rate. 4 The effect on gastric emptying was most probably correlated with a spasmogenic effect on the gastroduodenal junction, as pointed out in previous work.

Animals↗
PubMed1981

Histamine receptors in the guinea-pig duodenum.

Guinea-pig duodenum contracted by histamine or by acetylcholine was relaxed dose-dependently by a series of H2-receptor selective agonists namely dimaprit, impromidine, clonidine and tolazoline. This relaxation was not neurally mediated since it was not modified by tetrodotoxin nor was it exerted through sympathetic receptors because it was not modified by pretreatment with propranolol or phentolamine. Apparently it was connected with the H2-receptor stimulation more than to peculiarities of the single compounds. However a series of H2-blocker (metiamide, cimetidine, ranitidine or oxmetidine) were unable to counteract the effect of the H2-agonists or the relaxant effect of histamine in the presence of chlorpheniramine. This peculiar situation seems to indicate the existence of anomalous H2-receptors, susceptible to the action of the agonists by not to that of the antagonists.

Acetylcholine↗
PubMed1981

Effects of alkyl analogues of histamine and metiamide on the isolated guinea pig heart.

The effects of some substitutions in position 5(4) of the imidazole ring in the histamine and metiamide molecule were studied by means of isolated heart preparations from the guinea pig (atria and papillary muscle). Among the histamine analogues 5-methyl and 5-ethyl histamine were found to possess approximately the same intrinsic activity as histamine whereas 5-isopropylhistamine was shown to be absolutely inactive. Among the metiamide analogues the 5-ethyl derivative (etiamide) was found less effective than the parent substance but showed the same kind of competitive antagonism; the isopropyl derivative (isopropiamide) was found to be inactive up to a concentration of 3 X 10(-5) mol/l and to exert a non-competitive antagonism with 3 X 10(-4) mol/l. On the whole the atria and the papillary muscle preparations behaved quite similarly in regard to both the agonistic and the antagonistic compounds.

Animals↗
PubMed1981

Evidence for and against heterogeneity in the histamine H2-receptor population.

Evidence for and against heterogeneity in the histamine H2-receptor population is reported: it was based on different degrees of potency and also of efficacy among the H2-receptor-selective agonists; less striking but still evident differences in the potency of H2-antagonists; atypical interactions between H2-agonists and antagonists in particular experimental conditions and finally inability of H1- and H2-receptor antagonists to block some of the effects of histamine. Binding studies gave equivocal results. All the data reported in this review suggest that, although it is premature to speak about H2-receptor subtypes, further investigations are needed to check whether or not H2- and perhaps also H1-receptors represent homogeneous populations of histamine receptors.

Animals↗
PubMed1981

Effect of histamine and related compounds on gastric emptying of the conscious rat.

In conscious rats, histamine given intraperitoneally produced a delay in gastric emptying. A dose-dependent relationship was observed. The threshold dose was about 1 mg/kg, the calculated maximum dose 35 mg/kg. The inhibitory effect of histamine on gastric emptying was abolished by pretreatment with H1-receptor antagonists and mimicked by 2-aminoethylthiazole; on the contrary, an H2-receptor agonist (dimaprit) and H2 antagonists were completely ineffective. This suggested that receptors involved in delay of gastric emptying are of the H1 type. The inhibitory effect of histamine on gastric emptying was not modified by pretreatment with the well-known inhibitors of gastric secretion, metiamide and cimetidine. This is consistent with the idea that the delay in gastric emptying observed with histamine may not be related to the gastric properties of this compound.

Animals↗
PubMed1981

Effect of acute and chronic cimetidine administration on glucose tolerance and insulin secretion in man.

The effect of acute and chronic cimetidine administration on glucose tolerance and insulin secretion was studied in healthy male volunteers. Cimetidine was administered intravenously (4 mg X kg-1 followed by 0.7 mg X kg-1 X h-1) in acute studies and by oral route (1 g/die for 4 weeks) in long-term studies. Oral (100 g) or intravenous (0.5 g X kg-1) glucose was used as a stimulus for insulin secretion in both studies. Neither acute nor chronic cimetidine administration modified insulin secretion and glucose tolerance. These data are consistent with the idea that H2-receptors are not involved in the insulinogenic effect of glucose.

Administration, Oral↗
PubMed1981

Bombesin delays gastric emptying in the rat.

Bombesin, administered by the intraperitoneal route, delayed gastric emptying in conscious rats in a dose-dependent fashion (1--16 microgram/kg). This effect is unlikely to depend on systemic effects of the peptide and is most probably connected with the direct spasmogenic action on the gastroduodenal junction already pinpointed in previous investigations.

Animals↗
PubMed1981

Failure of drugs acting on H2-receptors to modify plasma prolactin levels in pituitary adenomas: evidence for a suprapituitary locus of action.

Cimetidine, which strongly stimulates prolactin release in healthy man, was unable to modify prolactin levels in prolactin-secreting pituitary adenomas. Furthermore, the infusion of 5-methylhistamine, an H2-receptor selective agonist, was equally ineffective. The results of these experiments together with the data reported in the literature suggest that H2-receptors modulate prolactin secretion at a hypothalamic level.

Adenoma↗
PubMed1981

[Effect of H2 histamine receptor blocking agents on the isolated lower esophageal sphincter (LES) of the rat].

A series of histamine H2-receptor antagonists were tested for their activity on the isolated lower esophageal sphincter (LES) of the rat. Burimamide, methiamide and cimetidine were found to be virtually inactive since they caused very weak contractions only with extremely high concentrations (up to 300 microgram/ml). Ranitidine exerted a contraction at each concentration tested (from 1 to 100 microgram/ml). Oxmetidine, the newest member of the family, caused a modest contraction in low concentrations (0.3 to 3 microgram/ml) but a remarkable relaxation in high concentrations (10 to 300 microgram/ml). A series of observations suggested that H2 receptors do not occur in the rat LES: a) the lack of interference on histamine-induced contractions by the H2-blockers; b) the effect of histamine was mimiced by 2-aminoethylthiazole (a selective H1-receptor agonist) and inhibited by chlorpheniramine (a H1-receptor antagonist); c) dimaprit (a selective H2-receptor agonist) failed to modify the LES tension even at the maximum doses tested. All of these observations are consistent with the idea that the effects of the H2-receptor antagonists showed in the present investigation are independent of H2-receptor blockade. The contracting effect of ranitidine which was inhibited by tetrodotoxin and abolished by atropine is probably connected with a stimulating of the cholinergic system so far never described in the literature. The relaxant effect of oxmetidine is apparently a myolitic effect independent of stimulation of specific receptors.

Animals↗
PubMed1981

Effect of TRH on pentagastrin-induced gastric acid secretion.

Thyrotrophin-releasing hormone (TRH) 20 and 30 micrograms . kg-1 i.v. exerted a moderate inhibition on pentagastrin stimulated gastric secretion in dogs provided with gastric fistula and Heidenhain pouch. The effect was more evident in the main stomach than in the denervated pouch. The inhibitory action of the tripeptide was observed, though to a lesser extent, also in gastric fistula cats, whereas it was completely absent in the anaesthetized rat. Our results showing poor and erratic effects of TRH obtained only with rather high intravenous doses, paralleled those obtained by other authors on gastrointestinal motility and support the suggestion that, if there is a physiological role for TRH in the gastrointestinal tract this is more likely connected with paracrine rather than with endocrine effects of the peptide.

Anesthesia↗
PubMed1981

Caerulein delays gastric emptying of solids in man.

Intravenous administration of caerulein (40 ng/kg) delayed gastric emptying of solids in man. Radiological examinations demonstrated that the peptide causes a marked contraction of the pyloric sphincter and a relaxation of the gastric corpus and fundus. Therefore the effect of caerulein on gastric emptying may be considered as the result of different actions on the distal and proximal stomach. Furthermore pretreatment of the subjects with cimetidine did not modify the effect of caerulein indicating an action independent of the gastric hypersecretory effect of the peptide. The action of caerulein on gastric emptying must be kept in mind when the peptide is employed in the treatment of some pathological conditions.

Adult↗