Effect of Ca2+ modulators on acetylcholine-induced phasic and tonic contractions and A23187-induced contractions in ileal longitudinal muscle and IP3 production.
The influence of different sources of Ca2+ on the Emax and ED50 values of acetylcholine (ACh)-induced phasic and tonic contractions and on A23187-induced contractions was studied using different extracellular Ca2+ concentrations ([Ca2+]o) and the Ca2+ modulators TMB-8 and D600. IP3 production induced by both stimulants was also studied. The results are compatible with: (a) the mobilization of Ca2+ from an intracellular source as a primary event in the phasic response. (b) The primary involvement of a D600-sensitive inward Ca2+ current in the ACh-tonic response. (c) An inward D600-sensitive Ca2+ current associated with the ionophore transported ion. (d) The involvement of an IP3 independent, TMB-8 sensitive mechanism of Ca2+ mobilization involved in the A23187-induced responses.
Macara
B
B
Laboratório de Farmacologia, Faculdade de Farmácia, Lisboa, Portugal.
Rico
J M
JM
D000109:Acetylcholine / Q000494:pharmacology*; D000818:Animals; D000001:Calcimycin / Q000494:pharmacology*; D002118:Calcium / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D005707:Gallic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D005711:Gallopamil / Q000494:pharmacology; D006168:Guinea Pigs; D007082:Ileum / Q000187:drug effects / Q000502:physiology; D066298:In Vitro Techniques; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism*; D009119:Muscle Contraction / Q000187:drug effects*
D000001:Calcimycin; D005711:Gallopamil; C006014:8-(N,N-diethylamino)octyl-3,4,5-trimethoxybenzoate; D005707:Gallic Acid; D015544:Inositol 1,4,5-Trisphosphate; D000109:Acetylcholine; D002118:Calcium