Chiravat SadavongvivadJutamaad SatayavivadVirapong PrachayasittikulLadda Mo-SuwunMahidol University2018-03-222018-03-221977-01-01General Pharmacology. Vol.8, No.4 (1977), 263-267030636232-s2.0-49349132222https://repository.li.mahidol.ac.th/handle/20.500.14594/103331. 1. Lowering temperature reduced maximal effects of all four common adrenoceptor agonists without any change in their potencies. 2. 2. Quinidine reduced their potencies slightly and lowered maximal effects only at high concentrations. 3. 3. Adenosine caused a large decrease in potency of isoprenaline but hardly affected that of phenylephrine. 4. 4. These and our previous results indicate that some endogeneous negative chronotropic agents can alter relative potencies of the agonists as well as characteristics of blockers. © 1977.Mahidol UniversityPharmacology, Toxicology and PharmaceuticsArticleSCOPUS10.1016/0306-3623(77)90024-6