Critical contribution of Na ⁺ ‐Ca ²⁺ exchanger to the Ca ²⁺ ‐mediated vasodilation activated in endothelial cells of resistance arteries

Abstract

Na-Ca exchanger (NCX) contributes to control the intracellular free Ca concentration ([Ca]), but the functional activation of NCX reverse mode (NCXrm) in endothelial cells is controversial. We evaluated the participation of NCXrm-mediated Ca uptake in the endothelium-dependent vasodilation of rat isolated mesenteric arterial beds. In phenylephrine-contracted mesenteries, the acetylcholine (ACh)-induced vasodilation was abolished by treatment with the NCXrm blockers SEA0400, KB-R7943, or SN-6. Consistent with that, the ACh-induced hyperpolarization observed in primary cultures of mesenteric endothelial cells and in smooth muscle of isolated mesenteric resistance arteries was attenuated by KB-R7943 and SEA0400, respectively. In addition, both blockers abolished the NO production activated by ACh in intact mesenteric arteries. In contrast, the inhibition of NCXrm did not affect the vasodilator responses induced by the Ca ionophore, ionomycin, and the NO donor, S-nitroso- N-acetylpenicillamine. Furthermore, SEA0400, KB-R7943, and a small interference RNA directed against NCX1 blunted the increase in [Ca] induced by ACh or ATP in cultured endothelial cells. The analysis by proximity ligation assay showed that the NO-synthesizing enzyme, eNOS, and NCX1 were associated in endothelial cell caveolae of intact mesenteric resistance arteries. These results indicate that the activation of NCXrm has a central role in Ca-mediated vasodilation initiated by ACh in endothelial cells of resistance arteries.-Lillo, M. A., Gaete, P. S., Puebla, M., Ardiles, N. M., Poblete, I., Becerra, A., Simon, F., Figueroa, X. F. Critical contribution of Na-Ca exchanger to the Ca-mediated vasodilation activated in endothelial cells of resistance arteries.

Type 2 Diabetes Alters Intracellular Ca2+ Handling in Native Endothelium of Excised Rat Aorta

“…However, there was no significant change in the initial Ca 2+ peak ( Figure 9F), in the plateau amplitude ( Figure 9F), or in the AUC ( Figure 9H). The same findings were obtained when the Ca 2+ signal induced by 300 µM ATP was measured in the presence of SEA0400 (SEA) (3 µM), which blocks both the forward and reverse mode of NCX [45] (Figure 10). Overall, these results demonstrate that NCX negatively regulates intracellular Ca 2+ clearing when rat aortic endothelium is stimulated with low (i.e., 20 µM) ATP concentration, although this effect significantly reduces the AUC only in LZDF rats.…”

Novel Pannexin‐1‐Coupled Signaling Cascade Involved in the Control of Endothelial Cell Function and NO‐Dependent Relaxation

“…Perfusion of the Isolated Mesenteric Arterial Bed. Rats were anesthetized with xylazine and ketamine (10 and 90 mg/kg, i.p., respectively), and the mesenteric arterial bed was isolated as described by Lillo et al [18]. Briefly, the superior mesenteric artery was cannulated and the mesentery was perfused at 2 mL/min with a warmed (37°C) Tyrode buffer solution (in mM: 118 NaCl, 5.4 KCl, 2.5 CaCl 2 , 1.2 KH 2 PO 4 , 1.2 MgSO 4 , 23.8 NaHCO 3 , and 11.1 glucose) that was bubbled with 95% O 2 -5% CO 2 to yield pH 7.35-7.45.…”

Crosstalk Between Vascular Redox and Calcium Signaling in Hypertension Involves TRPM2 (Transient Receptor Potential Melastatin 2) Cation Channel

“…These findings demonstrate tight coupling between VSMC Na + and Ca 2+ homeostasis. Mechanisms linking these processes may involve NCX, an antiporter that can operate in forward or reverse mode, depending on the combined effects of Na + and Ca 2+ gradients 17,18 . Increased [Na + ]i activates the reverse mode of NCX, allowing Ca 2+ entry via the exchanger into the VSMCs 41,42 .…”

“…Of these the plasmalemmal NCX is particularly important because its activity may be bimodal. In the forward mode NCX activation promotes Na + influx and Ca 2+ extrusion, however positive membrane potential and increased intracellular Na + favor reverse mode NCX activation causing Ca 2+ influx and increased [Ca 2+ ]i 17,18 . Although reverse mode NCX has been demonstrated in endothelial cells 19 , there has been debate regarding the influence of NCX operating in reverse mode in VSMCs and its role in vascular function is unclear 20,21 .…”