RESUMO
The routine procedure for analysing the drug action on isolated organs is the establishment of the dose-response relationship and its quantification. In the first part of the experiment, we established the dose-response relationship for acetylcholine, carbachol, betanechol and 5-hydroxytriptamine on isolated preparations of rat fundus. In the second part, we analyzed the development in time of the rat fundus response to a single concentration of each of the four agonists. The single concentrations used were slightly higher than the EC50 of the agonists eliciting an optimal response. Responses to betanechol and carbachol developed with essentially the same rate, while responses to acetylcholine and 5-hydroxytriptamine developed more rapidly and more slowly, respectively. Since the rate of response development is highly dependent on the type of the receptor the agonist activated, analysis of response development in time could be an useful adjunctive tool in the pharmacodynamic studies.