Effects of antagonists

FIGURE 6.1 Effects of antagonists on agonist dose-response curves, (a) Surmountable antagonism with no diminution of maxima and no limiting antagonism (competitive antagonists). 

Negus SS, Henriksen SJ, Mattox A, Pasternak GW, Portoghese PS, Takemori AE, Weinger MB, Koob GF. (1993). Effect of antagonists selective for mu, delta, and kappa opioid receptors on the reinforcing effects of heroin in rats. J Pharmacol Exp Ther. 265(3) 1245-52. 

The effect of antagonists and allosteric modulators can also be characterized at LGIG receptors expressed in Xenopus oocytes. The potency of an antagonist (IG50) can be determined by testing a range of... 

Ravdin JI, Murphy CF, Guerrant RL, Long-Krug SA Effect of antagonists of calcium and phospholipase A on the cytopathogenicity of Entamoeba histolytica. J Infect Dis 1985 152 542-549. 

Thompson, D.C., Altiere, R.J. and Diamond, L. (1988). The effects of antagonists of vasoactive intestinal peptide on nonadrenergic noncholineigic inhibitory responses in feline airways. Peptides 9, 443-447. 

The equation describing agonist-receptor occupancy under conditions of noncompetitive antagonism is given by Equation 6.8. The effect of antagonist on the maximal agonist-receptor occupancy (i.e., as [A] > oo) and compar-... 

Determine mode of antagonism Determine direct effects of antagonist... 

Determine effects of antagonist on full agonist DR Curves... 

Effect of Antagonist on Agonist Effect of Antagonist on Response... 

Figure 2.8 Effect of antagonists on the action of agonist drugs.

C. J. Fimmel, A. Etienne, T. Cilluffo, C. von Ritter, and T. Gasser. Long-term ambulatory gastric pH monitoring validation of a new method and effect of -antagonists. Gastroenterology 55 1842-1851 (1985). 

D Silva L et al (2005) Monitoring the effects of antagonists on protein-protein interactions with NMR spectroscopy. J Am Chem Soc 127(38) 13220-13226... 

Gaddum, J. H. (1936). The quantitiative effects of antagonistic drugs. The Journal of Physiology, 89, 79. 

The rabbit head-drop technique has proved to be a rapid, accurate method for determining intensity of paralyzing effects. One procedure (14, 15) involves slow intravenous injection in the ear with the dose being adjusted so that the neck muscles fail to lift the chin in 2)/ -3 min. The end-point is very clear and reproducible. Modifications have been made in the procedure so that one-shot median head-drop doses as well as mean head-drop doses by timed infusion can be obtained, and cross-over techniques have improved the accuracy (16-19, 19a). This method lends itself to determination of cumulative effects and of effectiveness of antagonists. Head-drop techniques have also been used with mice, dogs, and humans (20-22). 

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