Role of Na+/Ca2+ Exchanger–Mediated Ca2+ Entry in Pressure-Induced Myogenic Constriction in Rat Posterior Cerebral Arteries

Abstract

Abstract. The involvement of Ca2+ entry via the Na + /Ca 2+ exchanger (NCX) in myogenic constriction of rat posterior cerebral arteries was investigated. RT-PCR identified mRNA for NCX1, 2, and 3 in the arteries. Na] i , which was reduced by the NCX inhibitor SEA0400. SEA0400 inhibited the development, but not the steady-state, of pressureinduced myogenic constriction, whereas it decreased both the initial and sustained phases of [Ca 2+ ] i elevation. These results suggest that Ca 2+ entry via NCX is involved in the development, but not the steady-state, of pressure-induced myogenic constriction.

Attenuated renal vascular responses to acute angiotensin II infusion in smooth muscle-specific Na+/Ca2+exchanger knockout mice

“…Our results suggest that in an in vivo setting, ANG II stimulates NCX in renal vascular smooth muscle cells to increase Ca 2ϩ entry, thus contributing to ANG II-mediated constriction and that this effect is attenuated or absent in the NCX1 smϪ/Ϫ mice. Our results are consistent with several other reports that indicate that NCX1 normally mediates Ca 2ϩ entry in arteries with tone (14,15,35).…”

“…Several reports reveal that Ca 2ϩ entry via vascular NCX1 is involved in pressure-induced myogenic constriction (14,15,24,35). Furthermore, arteries from smooth muscle-specific NCX1 knockout (NCX1 smϪ/Ϫ ) mice exhibit reduced Ca 2ϩ entry into vascular smooth muscle cells and reduced myogenic tone (25,35).…”

Increased arterial smooth muscle Ca2+ signaling, vasoconstriction, and myogenic reactivity in Milan hypertensive rats

“…This augmentes MR (Fig. 1) and arterial tone (36,40,75) and, thus, increases peripheral vascular resistance and BP in MHS rats. It is especially noteworthy that ouabain-induced hypertension (59) and human idiopathic pulmonary hypertension also are associated with a marked upregulation of both NCX1 (77) and TRPC6 (73).…”

“…We cannot, however, exclude the possibility that other Na ϩ -selective channels (6,21) might also contribute to the Na ϩ entry that promotes NCX-mediated Ca 2ϩ entry. In contrast with the heart, where NCX1 primarily mediates Ca 2ϩ extrusion (18), in ASMCs, which are partially depolarized in arteries with tone, NCX1 primarily mediates Ca 2ϩ entry (36,40,76). The implication is that the upregulated TRPC6 and NCX1 (79) contribute to the enhanced Ca 2ϩ entry and elevated [Ca 2ϩ ] cyt (79).…”

Arterial α2-Na+pump expression influences blood pressure: lessons from novel, genetically engineered smooth muscle-specific α2mice

“…Some of these factors, for example, the greatly reduced expression of NCX1, which mainly mediates Ca 2ϩ entry in ASMCs (18,53,58), and SERCA2 (Fig. 3), may contribute to the delayed generation of MT (22,46) in ␣ 2 SM-DN mouse arteries. …”