Diltiazem and verapamil inhibit norepinephrine-stimulated 45Ca uptake in rabbit aorta.
The effects of two Ca antagonists, diltiazem (DZ) and verapamil (VP), on norepinephrine (NE)-stimulated 45Ca uptake in vascular smooth muscle from New Zealand White rabbit aortas were studied. Data were collected before, at 10, 30, and 60 min after drug addition, and during a simultaneous control period without drug addition. NE alone (6 X 10(-6) M) significantly increased 45Ca uptake from the extracellular space presumably by activating the receptor-operated Ca channel during excitation-contraction coupling. This effect was maximal by 10 min after NE addition and stable through the 60-min time point. Both VP (5 X 10(-5) M) and DZ (2.2 X 10(-7) M) inhibited the NE-stimulated 45Ca uptake at the 10- and 60-min time points, respectively. These data demonstrate that both DZ and VP inhibit 45Ca uptake from the extracellular space during activation of the receptor-operated Ca channel with NE. The effects of DZ and VP to inhibit NE-stimulated 45Ca uptake are demonstrated at concentrations which have been previously shown to cause dilation of vascular smooth muscle.
D000818:Animals; D001011:Aorta / Q000187:drug effects; D001552:Benzazepines / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D004110:Diltiazem / Q000494:pharmacology*; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000378:metabolism; D009638:Norepinephrine / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D011817:Rabbits; D014700:Verapamil / Q000494:pharmacology*
D001552:Benzazepines; D014700:Verapamil; D004110:Diltiazem; D002118:Calcium; D009638:Norepinephrine