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limit concentration 0.1 mM (the highest concentration,
which could be administered) of the tested compounds did
not reach the maximal effect, the parameter of efficacy rep-
resented a vasorelaxing response, expressed as a percentage
(%) of the contractile tone induced by KCl 20 mM, evoked by
this limit concentration. The parameter of potency was ex-
pressed as pIC50, calculated as the negative Logarithm of the
molar concentration of the tested compounds, evoking a half
reduction of the contractile tone induced by KCl 20 mM. The
pIC50 could not be calculated for those compounds showing
an efficacy parameter lower than 50%. The parameters of
efficacy and potency were expressed as mean standard
error, for 5-10 experiments. Student t test was selected as
statistical analysis, P < 0.05 was considered representative of
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