Involvement of calcium in the cardiac depressant actions of a garlic dialysate.
In order to elucidate a possible role for calcium on the negative cardiotropic effects of a garlic (Allium sativum L., Liliaceae) dialysate in rat atria we studied: (a) the effects of our extract 15 min after preincubation with high and low concentrations of extracellular calcium ([Ca2+]o) on left and right activity of rat atria. The negative inotropism of garlic dialysate increased with calcium 0.75 mM; in contrast, high level of calcium (4.5 mM) induced a significant reduction of this depressant effect. None of these treatments modified the negative chronotropism of garlic; (b) nifedipine (10(-9) to 10(-7) M, verapamil (10(-9) to 10(-7) M) and diltiazem (10(-9) to 10(-7) M) induced a concentration-dependent synergism of the log concentration-effect of garlic dialysate on left atria. Verapamil and diltiazem (10(-7)M), but not nifedipine increased the inhibitory chronotropism of garlic in right atria; (c) negative inotropic and chronotropic effects demonstrated by nifedipine (1 x 10(-10) to 1.1 x 10(-6) M) were antagonized as expected by preincubation with Bay K-8644. Depressant actions of garlic were not modified with this pretreatment. These results suggest that the negative inotropic effect of our garlic dialysate is related to [Ca2+]o availability. It is possible that a restriction of intracellular calcium contributes to this effect. However, the negative chronotropic effect of garlic is scarcely affected by these modifications.
Martín
N
N
Departamento de Farmacología, Facultad de Ciencias Biológicas, Universidad de Concepción, Chile.
Bardisa
L
L
Pantoja
C
C
Barra
E
E
Demetrio
C
C
Valenzuela
J
J
Barrios
M
M
Sepúlveda
M J
MJ
D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000633:toxicity; D000818:Animals; D002118:Calcium / Q000378:metabolism* / Q000633:toxicity; D002120:Calcium Channel Agonists / Q000633:toxicity; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D003956:Dialysis; D004110:Diltiazem / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004357:Drug Synergism; D005737:Garlic / Q000378:metabolism*; D006325:Heart Atria / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects*; D009543:Nifedipine / Q000494:pharmacology; D010936:Plant Extracts / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology / Q000627:therapeutic use; D010946:Plants, Medicinal; D051381:Rats; D014700:Verapamil / Q000494:pharmacology
D002120:Calcium Channel Agonists; D002121:Calcium Channel Blockers; D010936:Plant Extracts; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D014700:Verapamil; D004110:Diltiazem; D009543:Nifedipine; D002118:Calcium