M. Quevedo et al., Isobolographic analysis of the interaction between fenoldopam and levodopaon arterial blood pressure of the rat, J CARDIO PH, 36(3), 2000, pp. 413-415
Citations number
15
Categorie Soggetti
Cardiovascular & Respiratory Systems","Cardiovascular & Hematology Research
Fenoldopam (PD) and levodopa (LD) injected intravenously in rats in a noncu
mulative schedule induced dose-dependent reductions in mean arterial blood
pressure. The doses that induced a 50% reduction in the initial control mea
n arterial pressure (referred as ED50) were calculated by linear regression
analysis of the corresponding parallel dose-response curves and were 0.88
and 0.068 mg/kg, respectively. The interaction between the effects of FD an
d LD on pressure reduction was evaluated by simultaneous administration of
different fixed ratios of FD and LD (16:1) and obtaining a dose-response cu
rve. An isobolographic analysis was then performed, which showed that the e
xperimental point for the effect of the simultaneous administration of FD a
nd LD was significantly different from the theoretically calculated additiv
e point, denoting supradditivity. It was concluded that the effect of the c
ombination of FD and LD on mean blood pressure reduction was synergic and w
as probably due to an activation of D-1 vascular receptors by both drugs, i
n conjunction with an activation of beta(2) adrenoceptors by LD and a block
ing action of FD on postsynaptic alpha(1)-adrenoceptors.