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Results for “Narcotics”

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

Transport mechanisms for narcotics and narcotic antagonists in alimentary epithelia.

A study has been made of the transport of seven morphine analogs across short-circuited preparations of rat gastric mucosa, small intestine and colon in vitro. Net secretory transport of all of the compounds tested was observed in the experiments with stomach. In the intestine the weaker bases were not transported but the more ionized compounds were secreted; in the colon, the stronger bases were transported in the absorptive direction. These transport processes were not dependent on transmural gradients of pH and in some cases the pattern of transport was maintained in the presence of adverse pH gradients. Studies on the effects of concentration and of interactions between concurrently transported compounds provided no evidence for carrier-mediated mechanisms. It was suggested that these observations are explicable in terms of a double membrane system.

Animals↗
PubMed1997

Validation of Vibrio fisheri acute toxicity data: mechanism of action-based QSARs for non-polar narcotics and polar narcotic phenols.

Quantitative structure-activity relationships (QSARs) have been utilized to validate toxicity data to Vibrio fisheri (the acute Microtox test) at each of the 5-, 15- and 30-min endpoints. Statistically robust QSARs were found for chemicals acting by a non-polar narcosis mechanism of action (MOA). The baseline, non-polar narcosis QSARs were similar to those found in other aquatic organisms, thus indicating that for this MOA, the acute V. fisheri assay makes a suitable surrogate for higher test species. For the toxicity of phenols, previously modeled in other species with parameters describing membrane transport (i.e. hydrophobicity) and soft electrophilicity or ionization, no significant relationships were obtained. The use of acute V. fisheri toxicity data is not recommended for extrapolation to higher species for these compounds. Despite this recommendation, it was noted, however, that a 'minimal' phenolic toxicity was apparent that was analogous to polar narcosis in other species. This confirmed that a polar narcosis MOA does operate in the acute V. fisheri system analogous to other species. For all the compounds considered, there were highly significant correlations between the toxicities at each endpoint, indicating that data from different time endpoints were effectively interchangeable.

Narcotics↗