The new NO donor Terpy induces similar relaxation in mesenteric resistance arteries of renal hypertensive and normotensive rats.

The present work aimed to investigate the cellular mechanisms involved on the vasorelaxation induced by the new nitric oxide donor [Ru(terpy)(bdq)NO](3+) (Terpy) in isolated mesenteric resistance artery and to compare the vascular responses in isolated vessels from 2K and 2K-1C hypertensive rats. We have used this artery because it is important to the control of vascular resistance and consequently to the blood pressure control. The NO donor Terpy induced relaxation in a concentration-dependent way in mesenteric resistance arteries. There were no differences between renal hypertensive (2K-1C) and normotensive (2K) in Terpy-induced relaxation neither in NO released. The relaxation induced by Terpy was inhibited by the soluble guanylyl-cyclase (sGC) inhibitor ODQ both in 2K and in 2K-1C with similar amplitude. In agreement with these data, the protein expression of the subunits α1 and β1 of the enzyme sGC was not different between 2K-1C and 2K mesenteric bed. The relaxation induced by Terpy was inhibited by the cGMP-dependent protein kinase (G kinase) inhibitor or by the non-selective K(+) channel blocker tetraethylamonium (TEA), but with no difference between 2K-1C and 2K arteries. The relaxation induced by Terpy was also inhibited by the SERCA inhibitor thapsigargin in both groups. Taken together, these results show that the vascular relaxation induced by the NO donor [Ru(terpy)(bdq)NO](3+) involves the activation of NO/sGC/cGMP/GK pathway, activation of K(+) channels sensitive to TEA and SERCA in normotensive and renal hypertensive rat mesenteric resistance arteries. Surprisingly, Terpy-induced vasorelaxation is similar in mesenteric resistance arteries of renal hypertensive and normotensive rats.

Araújo AV ，Pereira AC ，Grando MD ，da Silva RS ，Bendhack LM ... -  《-》

NO donors induce vascular relaxation by different cellular mechanisms in hypertensive and normotensive rats.

This study investigated the intracellular mechanisms involved in the vasodilatation induced by the classic NO donor SNP and the non-classic NO donor cis-[Ru(bpy)2(py)(NO2)](PF6) (or RuBPY) in mesenteric resistance arteries obtained from renal hypertensive (2K-1C) and normotensive (2K) rats. On the basis of fluorimetric assays in cultured vascular smooth muscle cells (VSMCs) isolated from 2K-1C and 2K rats, we measured NO release from SNP and RuBPY, cytosolic Ca2+ concentration ([Ca2+]c), and reactive oxygen species (ROS) with the selective probes DAF-2DA, Fluo-3AM and the more selective probe for peroxynitrite (7-CBA), respectively. We determined isometric tension in mesenteric arteries to assess SNP- and RuBPY-induced relaxation. SNP and RuBPY released NO in comparable amounts in cultured aortic VSMCs from hypertensive 2K-1C and normotensive 2K rats. The NO0 scavenger hydroxocobalamin blunted NO release. Sarco/endoplasmic reticulum Ca2+ ATPase (SERCA) inhibition with thapsigargin reduced [Ca2+]c in normotensive 2K rat VSMCs only. ROS amounts were greater in hypertensive 2K-1C than in normotensive 2K rat VSMCs, but neither SNP nor RuBPY altered ROS concentrations in any of the groups. SNP and RuBPY induced similar relaxation in hypertensive 2K-1C and normotensive 2K rat mesenteric resistance arteries. The SNP and RuBPY-induced relaxation involves sGC and PKG activation. On the other hand, SNP but not RuBPY activates K+ channels. Interestingly, SERCA inhibition reduces SNP induced relaxation only in normotensive 2K rat mesenteric arteries whereas RuBPY-induced relaxation does not involve SERCA activation in both normotensive and hypertensive arteries. Our results indicate that SNP and RuBPY-induced mesenteric resistance artery relaxation involves NO/sGC/cGMP/PKG pathway activation. K+ channels and SERCA activation is required to SNP but not for RuBPY-induced relaxation. Moreover, SERCA seems to be impaired in hypertensive 2K-1C rat mesenteric resistance arteries although it does not impact SNP- or RuBPY-induced relaxation.

Araújo AV ，Andrade FA ，Paulo M ，de Paula TD ，Potje SR ，Pereira AC ，Bendhack LM ... -  《-》

NO donors-relaxation is impaired in aorta from hypertensive rats due to a reduced involvement of K(+) channels and sarcoplasmic reticulum Ca(2+)-ATPase.

To examine the vasodilatation induce by the NO donors, [Ru(terpy)(bdq)NO](3+) (TERPY) and sodium nitroprusside (SNP), and to compare their effects in aortic rings from hypertensive 2K-1C and normotensive 2K rats. Vascular reactivity was performed in aortic rings pre-contracted with phenylephrine (Phe 100nM). We have analyzed the maximal relaxation (Emax) and potency (pD(2)) of NO donors. Potency of SNP was greater than TERPY in both arterial groups. The vasodilatation induced by TERPY was greater in 2K than in 2K-1C, and it was inhibited by sGC inhibitor ODQ in 2K and in 2K-1C aortic rings. ODQ did not alter the efficacy to SNP, but it reduced its potency in 2K and 2K-1C. The blockade of K(+) channels reduced the potency of TERPY only in aortic rings of 2K. On the other hand, the potency of SNP was reduced in both 2K and 2K-1C. The combination of ODQ and TEA reduced the relaxation induced by TERPY and SNP in 2K and reduced the efficacy to SNP in 2K-1C aortic rings but it had no additional effect on the TERPY relaxation in 2K-1C aortas. The production of cGMP induced by TERPY was greater than that produced by SNP, which was similarly increased in 2K and 2K-1C. Sarcoplasmic reticulum Ca-ATPase inhibition only impaired the relaxation induced by SNP in 2K aortic rings. Taken together, our results provide evidences that in this model of hypertension, impaired K(+) channels activation by TERPY and SERCA activation by SNP may contribute to decreased vasodilatation.

Bonaventura D ，de Lima RG ，da Silva RS ，Bendhack LM ... -  《-》

Endothelial modulation of a nitric oxide donor complex-induced relaxation in normotensive and spontaneously hypertensive rats.

We hypothesized that endothelium modulates relaxation induced by a nitric oxide (NO) donor ruthenium complex (TERPY, [Ru(terpy)(bdq)NO]3+) in mesenteric arteries of normotensive and spontaneously hypertensive (SHR) rats in different ways. We analyzed the mechanism involved in TERPY-induced relaxation in the second and third branches of mesenteric arteries and investigated how endothelium contributes to the TERPY vasodilator effect on SHR blood vessels. TERPY induced concentration-dependent relaxation in endothelium-denuded (E-) and endothelium-intact (E+) mesenteric arteries of normotensive rats and SHR. Pretreatment with ODQ (which inhibits soluble guanylyl cyclase) or TEA (tetraethylammonium, which blocks potassium channels) significantly reduced the TERPY vasodilator effect on E- mesenteric arteries of normotensive rats and SHR. The presence of endothelium shifted the concentration-effect curves for TERPY in E+ mesenteric arteries of normotensive rats to the right. Conversely, the presence of endothelium shifted the concentration-effect curves for TERPY in the case of SHR E+ mesenteric arteries to the left, which suggested increased potency. L-NNA, a more selective endothelial NO synthase (eNOS) inhibitor, reduced TERPY potency in SHR. The presence of endothelium and notably of NOS contributed to the TERPY vasodilator action in SHR: TERPY promoted eNOS Ser1177 phosphorylation with consequent NO production and increased soluble guanylyl cyclase activity, which may have directly activated potassium channels.

Potje SR ，Troiano JA ，Grando MD ，Graton ME ，da Silva RS ，Bendhack LM ，Antoniali C ... -  《-》

C-type natriuretic peptide-induced relaxation through cGMP-dependent protein kinase and SERCA activation is impaired in two kidney-one clip rat aorta.

Hypertension underlies endothelial dysfunction, and activation of vasorelaxation signaling with low dependence on nitric oxide (NO) represents a good alternative for vascular modulation. C-type natriuretic peptide (CNP) causes relaxation by increasing cyclic guanosine 3',5'-monophosphate (cGMP) or Gi-protein activation through its natriuretic peptide receptor-B or -C, respectively. We have hypothesized that CNP could exerts its effects and could overcome endothelial dysfunction in two kidney-one clip (2K-1C) hypertensive rat aorta. Here, we investigate the intracellular signaling involved in CNP effects in hypertension. The 2K-1C hypertension was induced in male Wistar rats (200 g). CNP-induced vascular relaxation and cGMP production were investigated in rat thoracic aortas. The natriuretic peptide receptor-B and -C localization was evaluated by immunofluorescence. Calcium mobilization was assessed in endothelial cells from rat aortas. CNP induced similar relaxation in normotensive and 2K-1C hypertensive rat aortas, which increased after endothelium removal. CNP-induced relaxation involved natriuretic peptide receptor-B and -C activation in 2K-1C rats. Nitric oxide synthase (NOS) and soluble guanylyl cyclase (sGC) counter-regulated CNP-particulate GC (pGC) activation in aortas. CNP reduced endothelial calcium and increased cGMP production, which was lower in 2K-1C. CNP-induced cGMP-dependent protein kinase (PKG) and sarcoplasmic/endoplasmic reticulum Ca2+-ATPase (SERCA) activation was impaired in 2K-1C rat aorta. Our results indicated CNP triggered relaxation through its natriuretic peptide receptor-B and -C in 2K-1C rat aortas, and that CNP-induced relaxation overcomes endothelial dysfunction in hypertension. In addition, NOS and sGC activities counter-regulate CNP-pGC activation to induce vascular relaxation.

Pernomian L ，do Prado AF ，Silva BR ，de Paula TD ，Grando MD ，Bendhack LM ... -  《-》