title: The underlying bases of pharmacological results in agreement or disagreement with the law of initial value.
abstract: Dose-response studies in vitro and in vivo revealed four types of alterations of dose-response curves along with changes in the baseline, two of them in accordance and two in disagreement with Wilder's law of initial value (LIV). The following conclusions have been drawn: The magnitude of drug-induced changes is in agreement with the LIV under conditions where the ED50 of a compound studied is not affected by changes in the baseline. Disagreement with the LIV is due to factors which potentiate the action of a compound at higher initial values. Not the initial value or activity by itself determines the response to drugs or stimuli; the response is dependent on the factor(s) changing the initial value.
mesh_terms: D000818:Animals; D002217:Carbachol / Q000494:pharmacology; D002417:Cattle; D004305:Dose-Response Relationship, Drug; D006339:Heart Rate / Q000187:drug effects*; D006632:Histamine / Q000494:pharmacology; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects*; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D012016:Reference Values; D012701:Serotonin / Q000494:pharmacology; D014132:Trachea
chemical_list: D012701:Serotonin; D011189:Potassium Chloride; D006632:Histamine; D002217:Carbachol; D007545:Isoproterenol