Endothelial vasodilator production by uterine and systemic arteries. I. Effects of ANG II on PGI2 and NO in pregnancy

1996 ◽  
Vol 270 (6) ◽  
pp. H1914-H1923 ◽  
Author(s):  
R. R. Magness ◽  
C. R. Rosenfeld ◽  
A. Hassan ◽  
P. W. Shaul

Uterine vasculature is less responsive than systemic vasculature to angiotensin II (ANG II)-induced vasoconstriction. We hypothesized that pregnancy augments basal and ANG II-stimulated endothelial prostacyclin (PGI2) and/or nitric oxide (NO) production, which locally increase vascular smooth muscle (VSM) adenosine 3',5'-cyclic monophosphate (cAMP) and guanosine 3',5'-cyclic monophosphate (cGMP), respectively. Uterine (UA) and systemic arteries (SA) from pregnant (P) and nonpregnant (NP) sheep were incubated with isobutylmethylxanthine. Basal PGI2, cAMP, and cGMP production was 2.4-, 1.6-, and 5.9-fold greater (P < 0.01) in UA from P vs. NP sheep; endothelium removal lowered (P < 0.05) values 69, 44, and 88%. Basal SA PGI2 and cAMP, but not cGMP, also were elevated by pregnancy. Indomethacin (Indo; 100 microM) decreased PGI2 and cAMP, but not cGMP production; N omega-nitro-L-arginine methyl ester (L-NAME; 10 microM) and methylene blue (MB, 10 microM) only decreased cGMP. Basal UA, but not SA, NO synthase activity (conversion of [3H]arginine to [3H]citrulline), was 1.8-fold higher in pregnancy and decreased (P < 0.01) after endothelium removal and with L-NAME. ANG II (50 nM) increased PGI2 (86%) and cAMP (56%) production only in UA from P sheep (P < 0.05); this was abolished by endothelium removal or Indo. ANG II also increased (P < 0.01) cGMP production by UA from both groups but only by SA from P ewes; this was absent in denuded, L-NAME-, or MB-treated vessels. Stimulation of VSM cGMP production with sodium nitroprusside (50 microM) was inhibited by MB, but not L-NAME or endothelium removal. In pregnancy, endothelial PGI2 and NO production are enhanced and may contribute to attenuated ANG II vasoconstriction via VSM cAMP and cGMP.

1997 ◽  
Vol 272 (4) ◽  
pp. H1730-H1740 ◽  
Author(s):  
R. R. Magness ◽  
C. E. Shaw ◽  
T. M. Phernetton ◽  
J. Zheng ◽  
I. M. Bird

Pregnancy is characterized by elevations in uterine but not omental artery nitric oxide synthase (NOS)-specific activity. We hypothesized that increases in NO production during pregnancy are associated with elevations in protein expression of the constitutive isoform, endothelial cell NOS (ecNOS), in uterine but not systemic arteries. Arterial NOS-specific activity and guanosine 3',5'-cyclic monophosphate (cGMP) production were tested in pregnant sheep in the presence or absence [+5 mM ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid] of Ca2+. With the use of Western analysis, ecNOS and neuronal NOS (nNOS) constitutive isoform expressions were evaluated in intact and denuded [vascular smooth muscle (VSM)] uterine and systemic (omental and renal) arteries as well as in isolated endothelium-derived proteins from nonpregnant and pregnant sheep. Uterine and omental artery NOS activity and cGMP production were inhibited 75-85% by Ca2+ removal. ecNOS was localized only in uterine and systemic artery endothelium (not VSM) by immunohistochemistry and Western analysis; nNOS was not detected. Compared with nonpregnant ewes, pregnancy increased expression of ecNOS in uterine [2.1- to 4.2-fold (P < 0.0001)] and omental [1.3- to 2.2-fold (P = 0.032)] but not renal (P = 0.1367) artery endothelium. Increases in uterine were greater than in omental artery endothelium. Levels of plasma and urinary cGMP were elevated (P < 0.01) proportionally (1.8- to 2.0-fold) in pregnant versus nonpregnant ewes. During pregnancy, expression of uterine artery endothelium-derived (not VSM) ecNOS constitutive isoform is increased, whereas expression in systemic vessels shows little or no change.


1991 ◽  
Vol 261 (4) ◽  
pp. C642-C649 ◽  
Author(s):  
A. K. Ho ◽  
M. Girard ◽  
I. Young ◽  
C. L. Chik

In rat pinealocytes, activation of alpha 1-adrenergic receptors leads to increases in intracellular pH (pHi). In this study, the role of pHi on adrenergic regulation of cyclic nucleotide accumulation was investigated using ammonium chloride, which increased pHi, and sodium propionate, which reduced pHi. Ammonium chloride significantly enhanced the norepinephrine-stimulated adenosine 3',5'-cyclic monophosphate (cAMP) and guanosine 3',5'-cyclic monophosphate (cGMP) responses, while it selectively potentiated the isoproterenol (ISO)-stimulated cGMP response. Reduction of pHi by sodium propionate reduced the norepinephrine-stimulated cGMP accumulation by 70%, and its effect on the ISO-stimulated cGMP response was stimulatory. Treatment with sodium propionate effectively neutralized the enhancing effects of ammonium chloride on the adrenergic-stimulated cAMP and cGMP responses. These effects of sodium propionate and ammonium chloride on cyclic nucleotides appeared to reflect altered rate of synthesis, and they were also in part secondary to changes in intracellular Ca2+. Our findings indicate that the receptor-mediated changes in pHi may play an integral part in the adrenergic regulation of cAMP and cGMP production in rat pinealocytes.


1994 ◽  
Vol 267 (1) ◽  
pp. C236-C244 ◽  
Author(s):  
J. Geiger ◽  
C. Nolte ◽  
U. Walter

Stimulation of Ca2+ mobilization and entry by agonists such as ADP, thrombin, and thromboxane is an early step of platelet activation. Here, we compared the effects of adenosine 3',5'-cyclic monophosphate (cAMP)-elevating prostaglandins, guanosine 3',5'-cyclic monophosphate (cGMP)-elevating nitrovasodilators, membrane-permeant selective activators of cAMP- or cGMP-dependent protein kinases, and physiological endothelium-derived factors on the agonist-evoked Ca2+ mobilization and entry in human platelets. Prostaglandin E1, the prostacyclin analogue Iloprost, the nitric oxide (NO) donor 3-morpholinosydnonimine hydrochloride, and selective activators of cGMP- or cAMP-dependent protein kinase strongly inhibited the agonist-evoked Ca2+ mobilization from intracellular stores and associated late Ca2+ entry but had little effects on the rapid (1st) phase of ADP-evoked Ca2+ entry. During coincubation of platelets with endothelial cells, endothelium-derived factors that were released strongly inhibited platelet agonist-evoked Ca2+ mobilization and only moderately affected the rapid phase of ADP-evoked Ca2+ entry. These effects were partially prevented when endothelial cells were preincubated with cyclooxygenase and/or NO synthase inhibitors. Endothelial cells therefore produce sufficient quantities of labile platelet inhibitors whose effects on the platelet Ca2+ response resemble those observed with selective cAMP- and cGMP-dependent protein kinase activators.


1995 ◽  
Vol 269 (6) ◽  
pp. R1321-R1326 ◽  
Author(s):  
S. A. Davies ◽  
G. R. Huesmann ◽  
S. H. Maddrell ◽  
M. J. O'Donnell ◽  
N. J. Skaer ◽  
...  

A cardioacceleratory peptide, CAP2b, identified originally in the lepidopteran Manduca sexta, stimulates fluid secretion by Malpighian tubules of the dipteran Drosophila melanogaster. High-performance liquid chromatography analyses of adult D. melanogaster reveal the presence of a CAP2b-like peptide, that coelutes with M. sexta CAP2b and synthetic CAP2b and that has CAP2b-like effects on the M. sexta heart. CAP2b accelerates fluid secretion in tubules stimulated by adenosine 3',5'-cyclic monophosphate (cAMP) but has no effect on tubules stimulated by guanosine 3',5'-cyclic monophosphate (cGMP), implying that it acts through the latter pathway. By contrast, the action of leucokinin is additive to both cAMP and cGMP but not to thapsigargin, suggesting that leucokinin acts by the elevation of intracellular calcium. CAP2b stimulation elevates tubule cGMP levels but not those of cAMP. By contrast, leucokinin has no effect on levels of either cyclic nucleotide. Both CAP2b and cGMP increase transepithelial potential difference, suggesting that stimulation of vacuolar-adenosinetriphosphatase action underlies the corresponding increases in fluid secretion. Overall, the results show that a Drosophila CAP2b-related peptide acts to stimulate fluid secretion by Malpighian tubules through the cGMP-signaling pathway.


2008 ◽  
Vol 294 (1) ◽  
pp. C295-C305 ◽  
Author(s):  
James White ◽  
Theresa Guerin ◽  
Hollie Swanson ◽  
Steven Post ◽  
Haining Zhu ◽  
...  

In the current study, we examined whether diabetes affected the ability of HDL to stimulate nitric oxide (NO) production. Using HDL isolated from both diabetic humans and diabetic mouse models, we found that female HDL no longer induced NO synthesis, despite containing equivalent amounts of estrogen as nondiabetic controls. Furthermore, HDL isolated from diabetic females and males prevented acetylcholine-induced stimulation of NO generation. Analyses of both the human and mouse diabetic HDL particles showed that the HDLs contained increased levels of myristic acid. To determine whether myristic acid associated with HDL particles was responsible for the decrease in NO generation, myristic acid was added to HDL isolated from nondiabetic humans and mice. Myristic acid-associated HDL inhibited the generation of NO in a dose-dependent manner. Importantly, diabetic HDL did not alter the levels of endothelial NO synthase or acetylcholine receptors associated with the cells. Surprisingly, diabetic HDL inhibited ionomycin-induced stimulation of NO production without affecting ionomycin-induced increases in intracellular calcium. Further analysis indicated that diabetic HDL prevented calmodulin from interacting with endothelial NO synthase (eNOS) but did not affect the activation of calmodulin kinase or calcium-independent mechanisms for stimulating eNOS. These studies are the first to show that a specific fatty acid associated with HDL inhibits the stimulation of NO generation. These findings have important implications regarding cardiovascular disease in diabetic patients.


1998 ◽  
Vol 274 (1) ◽  
pp. C214-C220 ◽  
Author(s):  
Maria E. Pueyo ◽  
Jean-François Arnal ◽  
Jacques Rami ◽  
Jean-Baptiste Michel

Angiotensin II (ANG II) produces vasoconstriction by a direct action on smooth muscle cells via AT1 receptors. These receptors are also present in the endothelium, but their function is poorly understood. This study was therefore undertaken to determine whether ANG II elicits the release of nitric oxide (NO) from cultured rat aortic endothelial cells. NO production, measured by the accumulation of nitrite and nitrate, was enhanced by 10−7 M ANG II. The biological activity of the NO released by ANG II action was evaluated by measuring its guanylate cyclase-stimulating activity in smooth muscle cells. The guanosine 3′,5′-cyclic monophosphate (cGMP) content of smooth muscle cells was significantly increased by exposure of supernatant from ANG II-stimulated endothelial cells. These effects resulted from the activation of NO synthase, as they were inhibited by the l-arginine analogs. These ANG II actions were mediated by the AT1 receptor, as shown by their inhibition by the AT1 antagonist losartan. The cGMP production by reporter cells was inhibited by the calmodulin antagonist W-7, suggesting that ANG II activates endothelial calmodulin-dependent NO synthase. This hypothesis is also supported by the increase of intracellular free calcium induced by ANG II in endothelial cells. ANG II also stimulated luminol-enhanced chemiluminescence in endothelial cells. This effect was inhibited by N ω-monomethyl-l-arginine and superoxide dismutase, suggesting that this luminol-enhanced chemiluminescence reflected an increase in peroxynitrite production. Thus ANG II stimulates NO release from macrovascular endothelium, which may modulate the direct vasoconstrictor effect of ANG II on smooth muscle cells. However, this beneficial effect may be counteracted by the simultaneous production of peroxynitrite, which could contribute to several pathological processes in the vascular wall.


1980 ◽  
Vol 58 (3) ◽  
pp. 243-248 ◽  
Author(s):  
N. Schlageter ◽  
R. A. Janis ◽  
R. T. Gualtieri ◽  
O. Hechter

The effects of oxytocin and methacholine on cyclic nucleotide levels in estrogen-primed rabbit myometrium were studied in the presence and absence of 1-methyl-3-isobutyl xanthine (MIX), a phosphodiesterase inhibitor. In the absence of MIX, methacholine increased guanosine 3′,5′-cyclic monophosphate (cGMP) levels at a time when contraction was decreasing, but had no influence on adenosine 3′,5′-cyclic monophosphate (cAMP) levels. In contrast, oxytocin did not elevate cGMP, but rapidly increased cAMP levels. MIX (1 mM) increased both cAMP and cGMP levels. Oxytocin or methacholine further increased cGMP, indicating activation of guanylate cyclase. Oxytocin- but not methacholine-induced stimulation of guanylate cyclase was abolished in Ca2+-free solution. Oxytocin increased cAMP over the levels produced by MIX alone, whereas methacholine decreased cAMP below the MIX control values; these effects were insensitive to indomethacin. Tissue levels of cGMP and cAMP did not directly correlate with isometric tension. The results also indicate that both oxytocin and methacholine stimulate guanylate cyclase but have opposing effects on adenylate cyclase of rabbit myometrium.


1992 ◽  
Vol 262 (4) ◽  
pp. G774-G778 ◽  
Author(s):  
J. R. Grider ◽  
K. S. Murthy ◽  
J. G. Jin ◽  
G. M. Makhlouf

The source of nitric oxide (NO) and its role in neurally induced relaxation was examined in smooth muscle of the stomach and tenia coli. Field stimulation of gastric muscle strips was accompanied by frequency-dependent relaxation, vasoactive intestinal peptide (VIP) release, and NO production: the NO synthase inhibitor, NG-nitro-L-arginine (L-NNA) completely inhibited NO production and partly inhibited VIP release (52-54%) and relaxation (58-88%); inhibition of all three functions was reversed by L-arginine but not by D-arginine. In isolated gastric muscle cells, VIP caused relaxation and stimulated NO production: L-NNA completely inhibited NO production and partly inhibited relaxation; the inhibition was reversed by L-arginine but not by D-arginine. Abolition of NO production with only partial inhibition of relaxation implied that NO production from muscle cells induced by the action of VIP was partly responsible for relaxation. By contrast, field stimulation of tenia coli was accompanied by relaxation and VIP release but not by NO production. Neither VIP release nor relaxation was affected by L-NNA. In isolated muscle cells of tenia coli, VIP caused relaxation but did not stimulate NO production; relaxation in these cells was not affected by L-NNA. We conclude that 1) VIP is the primary relaxant transmitter in both gastric muscle and tenia coli, 2) the release of VIP in gastric muscle but not in tenia coli stimulates NO production from target muscle cells, and 3) NO amplifies the relaxant effect of VIP in muscle cells and acts presynaptically to enhance the release of VIP.


1993 ◽  
Vol 264 (3) ◽  
pp. G470-G477 ◽  
Author(s):  
J. G. Jin ◽  
K. S. Murthy ◽  
J. R. Grider ◽  
G. M. Makhlouf

The mechanism of action of vasoactive intestinal peptide (VIP) was examined in isolated gastric and taenia coli muscle cells and compared with that of nitric oxide (NO), sodium nitroprusside (SNP), and isoproterenol. In gastric muscle cells, VIP stimulated NO production, increased adenosine 3',5'-cyclic monophosphate (cAMP) and guanosine 3',5'-cyclic monophosphate (cGMP) levels, and induced relaxation in a concentration-dependent fashion. The NO synthase inhibitor NG-nitro-L-arginine abolished NO and cGMP production and partly inhibited relaxation. The soluble guanylate cyclase inhibitor LY 83583 abolished cGMP production and partly inhibited relaxation. (R)-p-adenosine 3',5'-cyclic phosphorothioate [(R)-p-cAMPS], a preferential inhibitor of cAMP-dependent protein kinase (cAK), and KT5823, a preferential inhibitor of cGMP-dependent protein kinase (cGK), partly inhibited relaxation separately and abolished relaxation in combination. The pattern implied that VIP induced relaxation by activation of cAK and by NO-mediated stimulation of cGMP and activation of cGK. In taenia coli muscle cells, VIP did not increase NO production or cGMP levels: relaxation was accompanied by an increase in cAMP and was partly inhibited by (R)-p-cAMPS and KT5823 and abolished by a combination of both inhibitors. Isoproterenol increased only cAMP levels in both cell types, which induced relaxation by activating cAK at low concentrations of agonist and both cAK and cGK at high concentrations in a pattern identical to that observed with VIP in taenia coli muscle cells. SNP and NO increased only cGMP levels in both cell types, which induced relaxation by activating cGK only. We conclude that cAK and cGK can be activated separately and mediate relaxation independently.(ABSTRACT TRUNCATED AT 250 WORDS)


2016 ◽  
Vol 310 (8) ◽  
pp. F748-F754 ◽  
Author(s):  
Vanesa D. Ramseyer ◽  
Pablo A. Ortiz ◽  
Oscar A. Carretero ◽  
Jeffrey L. Garvin

In thick ascending limbs (THALs), nitric oxide (NO) decreases NaCl reabsorption via cGMP-mediated inhibition of Na-K-2Cl cotransporter (NKCC2). In angiotensin (ANG II)-induced hypertension, endothelin-1 (ET-1)-induced NO production by THALs is impaired. However, whether this alters NO's natriuretic effects and the mechanisms involved are unknown. In other cell types, ANG II augments phosphodiesterase 5 (PDE5)-mediated cGMP degradation. We hypothesized that NO-mediated inhibition of NKCC2 activity and stimulation of cGMP synthesis are blunted via PDE5 in ANG II-induced hypertension. Sprague-Dawley rats were infused with vehicle or ANG II (200 ng·kg−1·min−1) for 5 days. ET-1 reduced NKCC2 activity by 38 ± 13% ( P < 0.05) in THALs from vehicle-treated rats but not from ANG II-hypertensive rats (Δ: −9 ± 13%). A NO donor yielded similar results as ET-1. In contrast, dibutyryl-cGMP significantly decreased NKCC2 activity in both vehicle-treated and ANG II-hypertensive rats (control: Δ−44 ± 15% vs. ANG II: Δ−41 ± 10%). NO increased cGMP by 2.08 ± 0.36 fmol/μg protein in THALs from vehicle-treated rats but only 1.06 ± 0.25 fmol/μg protein in ANG II-hypertensive rats ( P < 0.04). Vardenafil (25 nM), a PDE5 inhibitor, restored NO's ability to inhibit NKCC2 activity in THALs from ANG II-hypertensive rats (Δ: −60 ± 9%, P < 0.003). Similarly, NO's stimulation of cGMP was also restored by vardenafil (vehicle-treated: 1.89 ± 0.71 vs. ANG II-hypertensive: 2.02 ± 0.32 fmol/μg protein). PDE5 expression did not differ between vehicle-treated and ANG II-hypertensive rats. We conclude that NO-induced inhibition of NKCC2 and increases in cGMP are blunted in ANG II-hypertensive rats due to PDE5 activation. Defects in the response of THALs to NO may enhance NaCl retention in ANG II-induced hypertension.


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