The anti-oestrogen tamoxifen is a calcium antagonist in perfused rat mesentery.
The anti-oestrogen tamoxifen in the range 10(-7)-10(-5) M induced concentration-related inhibition of potassium-stimulated vasospasm in the isolated perfused rat mesentery vascular bed. In contrast, responses to noradrenaline did not fall below control levels until the tamoxifen concentration exceeded 4 X 10(-6) M. Recovery of the potassium-stimulated responses was also concentration-related. The most likely explanation is that while tamoxifen can obstruct the entry of extracellular calcium, it is unable to prevent the intracellular release of the ion by noradrenaline.
Lipton
A
A
Efamol Research Institute, Nova Scotia, Canada.
D000818:Animals; D002118:Calcium / Q000037:antagonists & inhibitors* / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005260:Female; D008638:Mesenteric Arteries / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D009638:Norepinephrine / Q000494:pharmacology; D010477:Perfusion; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013629:Tamoxifen / Q000494:pharmacology*; D014655:Vascular Resistance / Q000187:drug effects; D014661:Vasoconstriction / Q000187:drug effects
D013629:Tamoxifen; D011188:Potassium; D002118:Calcium; D009638:Norepinephrine