Possible Interaction: Vasoconstrictor Agents and Calcium Supplement

“Conclusions— Our results identify a novel mechanism by which NO can increase the efficacy of calcium , rising vasoactive agonists in the microvascular endothelium.”

“Intracellular calcium is an inhibitory second messenger and is increased after exposure of the JG cells to vasoconstrictors such as angiotensin II, a1-adrenergic agonists or endothelin [1].”

“ Vasoconstrictor agents enhance the entry of Ca++ into vascular myocytes; vasodilators usually depress it.”

“BK Ca are expressed in human UA and modulate vascular function by attenuating vasoconstrictor responses and contributing to nitric oxide-induced vasorelaxation.”

“Studies have shown that extracellular calcium modulates renal blood flow and GFR during infusion of vasoconstrictor substances , and that in dogs calcium antagonists blunt the vasoconstriction associated with contrast administration (15).”

“Other vasoactive agents have been shown to cause elevation of intracellular adenosine 3',5'-cyclic monophosphate (cAMP), Ca , and diacylglycerol.”

“These results indicate that vasoconstrictors and vasodilators may modulate smooth muscle contraction by changing the cytosolic Ca++ concentrations and also by changing the sensitivity of contractile elements to Ca++.”

“Contractions induced by vasoconstrictors were more resistant to the change of the Ca concentration than by electrical stimulation.”

“Thus, calcium addition augmented the blunted vasopressor response in high-altitude rats lungs, possibly by an effect on lung arteries.”

“Moreover, excessive systemic upregulation of nitric oxide synthase, stimulation of prostaglandin synthesis, and activation of ATP-sensitive potassium channels followed by reduced vascular entry of calcium ions are putative mechanisms in the reduced responsiveness to vasopressors.”