Emax and EC50 (half-maximal effective concentration) parameters are defined as the maximum response and the concentration level to reach 50% of the maximum response, and h is the hill coefficient which reflects the steepness of model structure.
Peak values were taken as the maximum response to the concentration of methacholine being tested, and were expressed as the percentage change relative to the saline control.
The maximum response and the concentration of drug causing 50% of the maximum response (EC50) were determined by fitting the Hill equation to the dose-response curves for each vessel.
Rmax (maximum response) and EC50 (concentration to produce 50% of maximum response) values for responses to 5-HT and ACh and all other data were compared by t-test or one-way anova followed by Student Newman Keul's multiple range test as appropriate.
The slopes of the regressions for the two halves of the data set were used to make inferences on the qualitative form of the dose-response relation: is there a maximum response at intermediate concentrations or not?
For comparative purposes, luminescence was normalized to DHT alone at coexposure concentration (maximum response, 100%) and solvent-only (ethanol) controls (minimum response, 0%).
The same effect is seen at the upper asymptote possibly due to the near infinite antibody concentration (maximum response) though not as pronounced as seen in the lower asymptote.
Concentration-response data were fitted with the equation Y = ((X) H · M /((X) H + (EC50) H ), where Y is response, X is agonist concentration, H is the Hill coefficient, M is maximum response, and EC50 is the concentration of agonist evoking 50% of the maximum response.
Concentration response curves were conventionally analyzed either by measuring maximum responses per agonist concentration or by averaging all data points per agonist concentration, taking into account differences in concentration time intervals (Myodata, DMT A/S, Aarhus, Denmark).
In contrast, acetylcholine- and bradykinin-induced relaxation (median effective concentration and maximum response) did not change with age.
