Cardiac microvascular endothelial cells express a functional Ca+ -sensing receptor.
The mechanism whereby extracellular Ca(2+) exerts the endothelium-dependent control of vascular tone is still unclear. In this study, we assessed whether cardiac microvascular endothelial cells (CMEC) express a functional extracellular Ca(2+)-sensing receptor (CaSR) using a variety of techniques. CaSR mRNA was detected using RT-PCR, and CaSR protein was identified by immunocytochemical analysis. In order to assess the functionality of the receptor, CMEC were loaded with the Ca(2+)-sensitive fluorochrome, Fura-2/AM. A number of CaSR agonists, such as spermine, Gd(3+), La(3+) and neomycin, elicited a heterogeneous intracellular Ca(2+) signal, which was abolished by disruption of inositol 1,4,5-trisphosphate (InsP(3)) signaling and by depletion of intracellular stores with cyclopiazonic acid. The inhibition of the Na(+)/Ca(2+) exchanger upon substitution of extracellular Na(+) unmasked the Ca(2+) signal triggered by an increase in extracellular Ca(2+) levels. Finally, aromatic amino acids, which function as allosteric activators of CaSR, potentiated the Ca(2+) response to the CaSR agonist La(3+). These data provide evidence that CMEC express CaSR, which is able to respond to physiological agonists by mobilizing Ca(2+) from intracellular InsP(3)-sensitive stores.
Berra Romani
Roberto
R
Department of Biomedicine, School of Medicine, Benemèrita Universidad Autònoma de Puebla, Puebla, Mexico.
Raqeeb
Abdul
A
Laforenza
Umberto
U
Scaffino
Manuela Federica
MF
Moccia
Francesco
F
Avelino-Cruz
Josè Everardo
JE
Oldani
Amanda
A
Coltrini
Daniela
D
Milesi
Veronica
V
Taglietti
Vanni
V
Tanzi
Franco
F
D000818:Animals; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism*; D004963:Estrenes / Q000494:pharmacology; D005682:Gadolinium / Q000494:pharmacology; D007211:Indoles / Q000494:pharmacology; D007811:Lanthanum / Q000494:pharmacology; D008536:Meglumine / Q000494:pharmacology; D032383:Myocytes, Cardiac / Q000378:metabolism*; D009355:Neomycin / Q000494:pharmacology; D010649:Phenylalanine / Q000494:pharmacology; D011760:Pyrrolidinones / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D044169:Receptors, Calcium-Sensing / Q000819:agonists / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012964:Sodium / Q000502:physiology; D013096:Spermine / Q000494:pharmacology; D014364:Tryptophan / Q000494:pharmacology; D010738:Type C Phospholipases / Q000502:physiology
D004963:Estrenes; D007211:Indoles; D011760:Pyrrolidinones; D012333:RNA, Messenger; D044169:Receptors, Calcium-Sensing; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; D013096:Spermine; D010649:Phenylalanine; D008536:Meglumine; D007811:Lanthanum; D014364:Tryptophan; D012964:Sodium; D005682:Gadolinium; D010738:Type C Phospholipases; D009355:Neomycin; C000543:cyclopiazonic acid