Ca2+ signaling in injured in situ endothelium of rat aorta.
The inner wall of excised rat aorta was scraped by a microelectrode and Ca2+ signals were investigated by fluorescence microscopy in endothelial cells (ECs) directly coupled with injured cells. The injury caused an immediate increase in the intracellular Ca2+ concentration ([Ca2+]i), followed by a long-lasting decay phase due to Ca2+ influx from extracellular space. The immediate response was mainly due to activation of purinergic receptors, as shown by the effect of P2X and P2Y receptors agonists and antagonists, such as suramin, alpha,beta-MeATP, MRS-2179 and 2-MeSAMP. Inhibition of store-operated Ca2+ influx did not affect either the peak response or the decay phase. Furthermore, the latter was: (i) insensitive to phospholipase C inhibition, (ii) sensitive to the gap junction blockers, palmitoleic acid, heptanol, octanol and oleamide, and (iii) sensitive to La3+ and Ni2+, but not to Gd3+. Finally, ethidium bromide or Lucifer Yellow did not enter ECs facing the scraped area. These results suggest that endothelium scraping: (i) causes a short-lasting stimulation of healthy ECs by extracellular nucleotides released from damaged cells and (ii) uncouples the hemichannels of the ECs facing the injury site; these hemichannels do not fully close and allow a long-lasting Ca2+ entry.
Berra-Romani
Roberto
R
Department of Physiological and Pharmacological Sciences, University of Pavia, V. Forlanini 6, 27100 Pavia, Italy.
Raqeeb
Abdul
A
Avelino-Cruz
José Everardo
JE
Moccia
Francesco
F
Oldani
Amanda
A
Speroni
Francisco
F
Taglietti
Vanni
V
Tanzi
Franco
F
D000244:Adenosine Diphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D001012:Aorta, Abdominal / Q000166:cytology; D001013:Aorta, Thoracic / Q000166:cytology; D020013:Calcium Signaling / Q000502:physiology*; D004730:Endothelium, Vascular / Q000187:drug effects / Q000293:injuries* / Q000378:metabolism*; D058910:Purinergic P2 Receptor Agonists; D058919:Purinergic P2 Receptor Antagonists; D051381:Rats; D018048:Receptors, Purinergic P2 / Q000378:metabolism; D013498:Suramin / Q000494:pharmacology
C111914:N(6)-methyl-2'-deoxyadenosine 3',5'-diphosphate; D058910:Purinergic P2 Receptor Agonists; D058919:Purinergic P2 Receptor Antagonists; D018048:Receptors, Purinergic P2; D013498:Suramin; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; C002630:alpha,beta-methyleneadenosine 5'-triphosphate