Inhibitory, definition

It is clear that, at this point, the definitive chemical characterization of the inhibitory material has yet to be done. Much is known concerning the distribution and the source of the material, and work on the biological basis if the observed inhibition is promising. However, the potential for the use of the material as an hydrilla-control agent will depend upon the identification and purification of the bio-active components detected in HPLC chromatograms. 

Some of the depressant behavioral effects of hallucinogens may involve inhibitory postsynaptic 5-HT receptors. For example, depressant effects of hallucinogens on startle and locomotor activity may result from activation of these receptors, since 5-HT itself has similar effects. Studies on supersensitivity are lacking, however, and, again, the absence of selective antagonists prevents definitive conclusions. 

Studies on competitive inhibition of Bi2 activity show that certain substituted benzimidazoles, purines, and pteridines have weak inhibitory effects in bacterial systems (SlOa). Substituted amides of Bi2 (S9) inhibited the growth-promoting effects of vitamin B12 in protozoic and bacterial systems (B5, B6). The anilide of B12 shows a definite inhibitory effect on maturation and proliferation of blood-forming cells of the chick embryo an opposite effect is induced by vitamin Bi2 (E2). 

On the basis of their findings they contend that the effect of almost any compound -hydrocarbons, alcohols, aldehydes, acids, amines, nitro-compounds, H20, H2S, S02, NH3 - can be co-catalytic or inhibitory, according to its concentration [66]. They extend quite unnecessarily the concept of co-catalyst to cover any substance which enhances the DP, and they thereby confuse and debase the originally perfectly precise meaning of the term co-catalyst a substance the presence of which is essential for the functioning of the catalyst [22, 71]. It follows of course from this definition that evidence on co-catalytic activity can be obtained only from rate measurements, and never from studies of DP. 

Atropine, a tertiary amine, competitively antagonizes acetylcholine activity. Full therapeutic doses of atropine produce definite and prolonged inhibitory effects on the motor activity of the stomach, duodenum, jejunum, ileum, and colon, characterized by a decrease in tone and in amplitude and frequency of peristaltic contractions. 

In the mouse, whereas no evidence of H3 receptors was found in isolated gastric glands (Muller et al., 1993), in the whole stomach, (R)a-methylhistamine actually increased, and thioperamide decreased acid secretion, thus indicating a definite stimulatory role for H3 receptors in this species (Table 2). Apparently, this excitatory effect, which contrasts with the observations obtained in other models, was due to an inhibitory effect on somatostatin release from fundic D cells (Schubert et al., 1993 Vuyyuru and Schubert 1993). Also, an inhibitory effect on somatostatin secretion mediated by H3 agonists was observed in other species (rat and dog). However, contrarily to what might have been expected, in these species, the inhibitory effect on somatostatin is not followed by an increase in acid secretion, but it is instead followed by a decrease, owing to the predominant H3-mediated inhibition on the release of excitatory mediators (histamine, acetylcholine) from other sites (ECL, cholinergic nerve terminals)... 

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