Interaction between noradrenaline and diltiazem in rat isolated atria.
1. The present study describes the effects of diltiazem (DIL) on noradrenaline (NA) activity in the isolated right atria of the rat. 2. Interactions between DIL and NA showed that DIL significantly shifted the concentration-response curve of NA to the right in a concentration-dependent manner. 3. The antagonist between DIL and NA is not consistent with a competitive antagonist since the slope is significantly lower than the unity. 4. A high calcium solution (4.5 mM) significantly increased the chronotropic effects of noradrenaline. 5. These results suggest that influx of calcium through calcium antagonist sensitive channels may be involved in linking of chronotropic responses to activation of alpha 1-adrenoceptors.
Gonzalez-Sicilia
L
L
Department of Pharmacology, Faculty of Medicine, Murcia, Spain.
Laorden
M L
ML
Hernández
J
J
Ruiz
F
F
Perez
D
D
D000818:Animals; D002118:Calcium / Q000494:pharmacology; D004110:Diltiazem / Q000494:pharmacology*; D006321:Heart / Q000187:drug effects*; D006339:Heart Rate / Q000187:drug effects; D066298:In Vitro Techniques; D008297:Male; D009206:Myocardium / Q000378:metabolism; D009638:Norepinephrine / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
D004110:Diltiazem; D002118:Calcium; D009638:Norepinephrine