Endothelial cell calcium increases during flow-induced dilation in isolated arterioles.
The influence of flow on endothelial intracellular calcium concentration ([Ca2+]i) was determined in intact, isolated arterioles by selectively loading endothelial cells with the calcium-sensitive fluorescent dye fura-2. A fluorescence microscope coupled to a digital image processor was used to simultaneously measure fura-2 fluorescence and microvessel diameter. Flow through the arteriole significantly increased endothelial [Ca2+]i and dilated arterioles. Acetylcholine also increased in endothelial [Ca2+]i and caused vasodilation. In comparison, adenosine did not alter endothelial [Ca2+]i but dilated arterioles. Removal of the endothelium abolished the responses to flow and acetylcholine but not adenosine. These results provide strong support for the involvement of calcium in endothelium-dependent dilation of isolated arterioles by flow and agonists and emphasize the importance of studying endothelial function in intact vessels.
Falcone
J C
JC
Department of Medical Physiology, Texas A&M University Health Science Center, College Station 77843-1114.
Kuo
L
L
Meininger
G A
GA
D000109:Acetylcholine / Q000494:pharmacology; D000241:Adenosine / Q000494:pharmacology; D000818:Animals; D001160:Arterioles / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D002118:Calcium / Q000378:metabolism / Q000502:physiology*; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D005456:Fluorescent Dyes; D016257:Fura-2 / Q000031:analogs & derivatives; D066298:In Vitro Techniques; D008297:Male; D051381:Rats; D012039:Regional Blood Flow; D014664:Vasodilation
D005456:Fluorescent Dyes; C049925:fura-2-am; D000241:Adenosine; D000109:Acetylcholine; D002118:Calcium; D016257:Fura-2