scholarly journals Shear-induced modulation of vasoconstriction in the hepatic artery and portal vein by nitric oxide

1998 ◽  
Vol 274 (2) ◽  
pp. G253-G260 ◽  
Author(s):  
M. Paula Macedo ◽  
W. Wayne Lautt
Keyword(s):  
Nitric Oxide ◽  
Blood Pressure ◽  
Shear Stress ◽  
Methyl Ester ◽  
Portal Vein ◽  
Hepatic Artery ◽  
Nerve Stimulation ◽  
Perfusion Pressure ◽  
No Synthase

The effect of shear stress on nitric oxide (NO)-mediated suppression of sympathetic nerve (2–6 Hz)- and norepinephrine (0.5 μg ⋅ kg−1 ⋅ min−1)-induced vasoconstriction in the hepatic artery (HA) and portal vein (PV) was studied using a perfusion circuit to regulate blood pressure and flow in the cat liver in situ. Holding flow constant resulted in increased shear stress during constriction; holding pressure steady prevented changes in shear stress. When shear stress was allowed to rise, the vasoconstriction (indicated by elevation in perfusion pressure) in response to nerve stimulation and norepinephrine was significantly potentiated after NO synthase blockade using N G-nitro-l-arginine methyl ester (l-NAME, 2.5 mg/kg iv) in both the HA and PV (response to nerves: HA control 28.8 ± 6.5 mmHg,l-NAME 62.7 ± 14.6 mmHg; PV control 1.5 ± 0.5 mmHg,l-NAME 3.3 ± 0.5 mmHg; response to norepinephrine: HA control 32.4 ± 9.0 mmHg, l-NAME 60.3 ± 8.0 mmHg; PV control 1.3 ± 0.3 mmHg,l-NAME 3.4 ± 0.7 mmHg). The potentiation was reversed byl-arginine (75 mg/kg). When shear stress was held constant by maintaining constant perfusion pressure, l-NAME did not cause potentiation of vasoconstriction. The data are consistent with the hypothesis that elevated shear stress in the hepatic blood vessels leads to NO-dependent postjunctional modulation of vasoconstriction.

Nitric oxide mediates hepatic arterial vascular escape from norepinephrine-induced constriction

1999 ◽  
Vol 277 (6) ◽  
pp. G1200-G1206 ◽  
Author(s):  
Zhi Ming ◽  
Chao Han ◽  
W. Wayne Lautt
Keyword(s):  
Nitric Oxide ◽  
Blood Flow ◽  
Methyl Ester ◽  
Portal Vein ◽  
Hepatic Artery ◽  
Maximum Point ◽  
Constant Flow ◽  
No Formation ◽  
Perfusion Model ◽  
Flow Perfusion

The involvement of nitric oxide (NO) in the vascular escape from norepinephrine (NE)-induced vasoconstriction was investigated in the hepatic arterial vasculature of anesthetized cats. The hepatic artery was perfused by free blood flow or pump-controlled constant-flow, and NE (0.15 and 0.3 μg ⋅ kg−1 ⋅ min−1, respectively) was infused through the portal vein. In the free-flow perfusion model, the NE-induced hepatic vasoconstriction recovered from the maximum point of the constriction, resulting in 36.6 ± 5.9% vascular escape. Blockade of NO formation with N ω-nitro-l-arginine methyl ester (l-NAME, 2.5 mg/kg ipv) potentiated NE-induced maximum vasoconstriction, and the potentiation was reversed byl-arginine (75 mg/kg ipv). Furthermore, NE-induced vasoconstriction became more stable after l-NAME, resulting in an inhibition of vascular escape (7.5 ± 3.3%), and the inhibition was reversed by l-arginine (23.0 ± 6.4%). Similar potentiation of NE-induced vasoconstriction and inhibition of hepatic vascular escape by l-NAME (40.4 ± 4.3% control vs. 10.2 ± 3.7% post-l-NAME escape) and the reversal byl-arginine were also observed in the constant-flow perfusion model. The data suggest that NO is the major endogenous mediator involved in the hepatic vascular escape from NE-induced vasoconstriction.

Selective neuronal nitric oxide synthase inhibition blocks furosemide-stimulated renin secretion in vivo

1995 ◽  
Vol 269 (1) ◽  
pp. F134-F139 ◽  
Author(s):  
W. H. Beierwaltes
Keyword(s):  
Nitric Oxide ◽  
Blood Pressure ◽  
Nitric Oxide Synthase ◽  
Perfusion Pressure ◽  
Renal Perfusion ◽  
Macula Densa ◽  
Renin Secretion ◽  
Renal Perfusion Pressure ◽  
Neuronal Nos ◽  
Oxide Synthase

The macula densa is a regulatory site for renin. It contains exclusively the neuronal isoform of nitric oxide synthase (NOS), suggesting NO could stimulate renin secretion through the macula densa pathway. To test whether neuronal NOS mediates renin secretion, renin was stimulated by either the renal baroreceptor or the diuretic furosemide (acting through the macula densa pathway). Renin secretion rate (RSR) was measured in 12 Inactin-anesthetized rats at normal (104 +/- 3 mmHg) and reduced renal perfusion pressure (65 +/- 1 mmHg), before and after selective blockade of the neuronal NOS with 7-nitroindazole (7-NI, 50 mg/kg ip). 7-NI had no effect on basal blood pressure (102 +/- 2 mmHg) or renal blood flow (RBF). Decreasing renal perfusion pressure doubled RSR from 11.8 +/- 3.3 to 22.9 +/- 5.7 ng ANG I.h-1.min-1 (P < 0.01) (ANG I is angiotensin I). Similarly, in 7-NI-treated rats, reduced perfusion doubled RSR from 8.5 +/- 1.8 to 20.5 +/- 6.2 ng ANG I.h-1.min-1 (P < 0.01). Renal hemodynamics and RSR were measured in response to 5 mg/kg iv furosemide in 12 control rats and 11 rats treated with 7-NI. Blocking neuronal NOS did not alter blood pressure (102 +/- 2 mmHg), RBF (5.8 +/- 0.4 ml.min-1.g kidney wt-1), or renal vascular resistance (18.7 +/- 1.4 mmHg.ml-1.min.g kidney wt).(ABSTRACT TRUNCATED AT 250 WORDS)

Systemic and regional hemodynamics after nitric oxide synthase inhibition: role of a neurogenic mechanism

1994 ◽  
Vol 267 (1) ◽  
pp. R84-R88 ◽  
Author(s):  
M. Huang ◽  
M. L. Leblanc ◽  
R. L. Hester
Keyword(s):  
Nitric Oxide ◽  
Blood Pressure ◽  
Cardiac Output ◽  
No Synthase ◽  
Before And After ◽  
Regional Hemodynamics ◽  
Autonomic Blockade ◽  
Infusion Of Norepinephrine ◽  
Oxide Synthase

The study tested the hypothesis that the increase in blood pressure and decrease in cardiac output after nitric oxide (NO) synthase inhibition with N omega-nitro-L-arginine methyl ester (L-NAME) was partially mediated by a neurogenic mechanism. Rats were anesthetized with Inactin (thiobutabarbital), and a control blood pressure was measured for 30 min. Cardiac output and tissue flows were measured with radioactive microspheres. All measurements of pressure and flows were made before and after NO synthase inhibition (20 mg/kg L-NAME) in a group of control animals and in a second group of animals in which the autonomic nervous system was blocked by 20 mg/kg hexamethonium. In this group of animals, an intravenous infusion of norepinephrine (20-140 ng/min) was used to maintain normal blood pressure. L-NAME treatment resulted in a significant increase in mean arterial pressure in both groups. L-NAME treatment decreased cardiac output approximately 50% in both the intact and autonomic blocked animals (P < 0.05). Autonomic blockade alone had no effect on tissue flows. L-NAME treatment caused a significant decrease in renal, hepatic artery, stomach, intestinal, and testicular blood flow in both groups. These results demonstrate that the increase in blood pressure and decreases in cardiac output and tissue flows after L-NAME treatment are not dependent on a neurogenic mechanism.

Effects of NG-nitro-L-arginine methyl ester on renal function and blood pressure

1991 ◽  
Vol 261 (6) ◽  
pp. F1033-F1037 ◽  
Author(s):  
V. Lahera ◽  
M. G. Salom ◽  
F. Miranda-Guardiola ◽  
S. Moncada ◽  
J. C. Romero
Keyword(s):  
Nitric Oxide ◽  
Blood Pressure ◽  
Renal Function ◽  
Methyl Ester ◽  
Renal Plasma Flow ◽  
Urinary Sodium Excretion ◽  
Systemic Blood Pressure ◽  
Synthesis Inhibitor ◽  
Renal Changes ◽  
Dose Dependent

The dose-dependent effects of intravenous infusions of nitric oxide (NO) synthesis inhibitor, NG-nitro-L-arginine methyl ester (L-NAME; 0.1, 1, 10, and 50 micrograms.kg-1.min-1), were studied in anesthetized rats to determine whether the inhibitory actions of L-NAME are manifested primarily in alterations of renal function or whether they are the consequences of the increase in systemic blood pressure. Mean arterial pressure (MAP) was not altered by the intravenous L-NAME infusions of 0.1 and 1.0 microgram.kg-1.min-1. However, 0.1 microgram.kg-1.min-1 L-NAME induced a 30% decrease in urine flow rate (UV). The administration of 1.0 microgram.kg-1.min-1 L-NAME, in addition to decreasing UV, also decreased urinary sodium excretion (UNaV) and renal plasma flow (RPF). The intravenous L-NAME infusions of 10.0 and 50.0 microgram.kg-1.min-1 intravenous L-NAME infusions of 10.0 and 50.0 microgram.kg-1.min-1 produced significant increases in MAP that reversed the initial fall in UV and UNaV, despite decreasing RPF and glomerular filtration rate (GFR). The administration of L-arginine alone (10 micrograms.kg-1.min-1) did not modify any of the parameters measured, but it effectively prevented all the hemodynamic and renal changes induced by the infusion of 50 micrograms.kg-1.min-1 L-NAME. These results suggest that the decrease in nitric oxide production induced by the intravenous infusion of L-NAME affects renal excretion of sodium and water in the absence of any significant change in blood pressure. At larger doses, L-NAME also produces hypertension that overrides the initial antinatriuretic effect.

Contribution of Vascular Nitric Oxide to Basal Blood Pressure in Conscious Spontaneously Hypertensive Rats and Normotensive Wistar Kyoto Rats

1995 ◽  
Vol 89 (2) ◽  
pp. 177-182 ◽  
Author(s):  
Naoyoshi Minami ◽  
Yutaka Imai ◽  
Jun-Ichiro Hashimoto ◽  
Keishi Abe
Keyword(s):  
Nitric Oxide ◽  
Blood Pressure ◽  
Mean Arterial Pressure ◽  
Methyl Ester ◽  
Spontaneously Hypertensive Rats ◽  
Hypertensive Rats ◽  
Spontaneously Hypertensive ◽  
Wistar Kyoto Rats ◽  
Basal Blood Pressure ◽  
Wistar Kyoto

1. The aim of this study was to clarify the extent to which vascular nitric oxide contributes to basal blood pressure in conscious spontaneously hypertensive rats and normotensive Wistar Kyoto rats. 2. The contribution of vascular nitric oxide to maintenance of blood pressure was estimated by measuring the pressor response to an intravenous injection of nitric oxide synthase inhibitor, Nω-l-arginine methyl ester, given after serial injections of captopril, vasopressin V1-receptor antagonist (V1-antagonist) and ganglion blocker (pentolinium) in conscious spontaneously hypertensive and Wistar Kyoto rats aged 20–28 weeks. To estimate the ‘amplifier property’ of hypertrophied vasculature in spontaneously hypertensive rats, which is known to modulate pressor responses, the lower blood pressure plateau after serial injections of captopril, V1-antagonist and pentolinium and the maximum blood pressure elicited by subsequent injection of increasing doses of phenylephrine were also measured. 3. The serial injections of captopril, V1-antagonist and pentolinium decreased mean arterial pressure from 164 ± 9 mmHg to 67 ± 2 mmHg and from 117 ± 2 mmHg to 49 ± 1 mmHg in spontaneously hypertensive and Wistar Kyoto rats respectively. The subsequent injection of Nω-l-arginine methyl ester restored mean arterial pressure almost to its control levels in both spontaneously hypertensive and Wistar Kyoto rats. The absolute changes in mean arterial pressure elicited by Nω-l-arginine methyl ester were significantly greater in spontaneously hypertensive than in Wistar Kyoto rats (P < 0.01), but there was no significant difference in the responses to Nω-l-arginine methyl ester when they were expressed as percentages of either the lower blood pressure plateau or maximum blood pressure. 4. These results indicate that basal blood pressure in both spontaneous hypertensive and Wistar Kyoto rats is maintained by a balance between vascular nitric oxide and major pressor systems. They also suggest that the vasodilatory effect of vascular nitric oxide does not differ between spontaneously hypertensive and Wistar Kyoto rats, and that the increased pressor effect of Nω-l-arginine methyl ester in spontaneously hypertensive rats is due to a vascular amplifier mechanism.

Cellular Localization of Inducible Nitric Oxide Synthase in Experimental Endotoxic Shock in the Rat

1994 ◽  
Vol 87 (2) ◽  
pp. 179-186 ◽  
Author(s):  
H. Terence Cook ◽  
Alison J. Bune ◽  
Albertine S. Jansen ◽  
G. Michael Taylor ◽  
Rashpal K. Loi ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
In Situ Hybridization ◽  
Cellular Localization ◽  
Endotoxic Shock ◽  
No Synthase ◽  
Similar Distribution ◽  
Mouse Macrophage ◽  
Inducible No Synthase ◽  
Monocytes And Macrophages

1. Endotoxin induces a shock-like syndrome with increased nitric oxide synthesis. To clarify the cellular source of NO in endotoxic shock we used immunohistochemistry and in situ hybridization to localize inducible NO synthase in rats given lipopolysaccharide or Corynebacterium parvum and lipopolysaccharide. Immunohistochemistry was carried out with an antibody raised against a synthetic peptide of mouse macrophage NO synthase. In situ hybridization was performed with 35S-labelled oligonucleotide probes corresponding to cDNA sequences common to mouse macrophage inducible NO synthase and rat vascular smooth inducible NO synthase. Monocytes and macrophages were identified by immunohistochemistry with the mouse monoclonal antibody ED1. 2. After lipopolysaccharide alone, the major site of NO synthase induction was monocytes and macrophages in multiple organs, principally liver and spleen. Bronchial, bile duct, intestinal and bladder epithelium and some hepatocytes also expressed inducible NO synthase. Expression peaked at 5 h and had returned to normal by 12 h except in spleen. 3. After priming with C. parvum, lipopolysaccharide led to a similar distribution of inducible NO synthase as lipopolysaccharide alone, but in addition there was more prominent hepatocyte staining, staining in macrophage granulomas in the liver and inducible NO synthase was present in some endothelial cells in the aorta. 4. These findings provide a direct demonstration of the cellular localization of inducible NO synthase after lipopolysaccharide.

Release of nitric oxide and prostaglandin H2 to acetylcholine in skeletal muscle venules

1997 ◽  
Vol 272 (6) ◽  
pp. H2541-H2546 ◽  
Author(s):  
G. Dornyei ◽  
G. Kaley ◽  
A. Koller
Keyword(s):  
Nitric Oxide ◽  
Skeletal Muscle ◽  
Perfusion Pressure ◽  
Thromboxane A2 ◽  
No Synthase ◽  
Gracilis Muscle ◽  
Vasoactive Agents ◽  
Before And After ◽  
Higher Doses

The role of endothelium in regulating venular resistance is not well characterized. Thus we aimed to elucidate the endothelium-derived factors involved in the mediation of responses of rat gracilis muscle venules to acetylcholine (ACh) and other vasoactive agents. Changes in diameter of perfusion pressure (7.5 mmHg)- and norepinephrine (10(-6) M)-constricted venules (approximately 225 microns in diam) to cumulative doses of ACh (10(-9) to 10(-4) M) and sodium nitroprusside (SNP, 10(-9) to 10(-4) M), before and after endothelium removal or application of various inhibitors, were measured. Lower doses of ACh elicited dilations (up to 42.1 +/- 4.7%), whereas higher doses of ACh resulted in smaller dilations or even constrictions. Endothelium removal abolished both ACh-induced dilation and constriction. In the presence of indomethacin (2.8 x 10(-5) M), a cyclooxygenase blocker, or SQ-29548 (10(-6) M), a thromboxane A2-prostaglandin H2 (PGH2) receptor antagonist, higher doses of ACh caused further dilation (up to 72.7 +/- 7%) instead of constriction. Similarly, lower doses of arachidonic acid (10(-9) to 10(-6) M) elicited dilations that were diminished at higher doses. These reduced responses were, however, reversed to substantial dilation by SQ-29548. The nitric oxide (NO) synthase blocker, N omega-nitro-L-arginine (L-NNA, 10(-4) M), significantly reduced the dilation to ACh (from 30.6 +/- 5.5 to 5.4 +/- 1.4% at 10(-6) M ACh). In contrast, L-NNA did not affect dilation to SNP. Thus ACh elicits the release of both NO and PGH2 from the venular endothelium.

Capillary hydraulic conductivity is decreased by nitric oxide synthase inhibition

1995 ◽  
Vol 268 (5) ◽  
pp. H1856-H1861 ◽  
Author(s):  
R. E. Rumbaut ◽  
M. K. McKay ◽  
V. H. Huxley
Keyword(s):  
Nitric Oxide ◽  
Hydraulic Conductivity ◽  
Guanylate Cyclase ◽  
Soluble Guanylate Cyclase ◽  
No Synthase ◽  
Capillary Water ◽  
Cell Monolayers ◽  
Study Support ◽  
Oxide Synthase

Nitric oxide (NO) has been reported to modulate microvascular permeability to solutes in whole organs, venules, and cultured endothelial cell monolayers. NO derived from L-arginine via NO synthase activates soluble guanylate cyclase in vascular smooth muscle and endothelial cells. While the effects of NO on capillary water permeability have not been characterized, other activators of guanylate cyclase, such as sodium nitroprusside and atrial natriuretic peptide, increase capillary hydraulic conductivity (Lp). We hypothesized that inhibition of NO synthase with the arginine analogue, NG-monomethyl-L-arginine (L-NMMA), would decrease Lp from control levels. Lp was assessed in situ in single perfused frog mesenteric capillaries, first during control conditions (Lcontrolp) and then during superfusion (Ltestp) with either L-NMMA, NG-monomethyl-D-arginine (D-NMMA), a biologically inert enantiomer, or L-NMMA and L-arginine. Superfusion with 1 microM L-NMMA caused a decrease in Lp (Ltestp/Lcontrolp = 0.6 +/- 0.1, P < 0.001), whereas 1 microM D-NMMA was without effect on Lp (Ltestp/Lcontrolp = 1.0 +/- 0.2). The decrease in Lp by 1 microM L-NMMA was not only prevented by the presence of excess L-arginine (100 microM), but Lp increased from control (Ltestp/Lcontrolp = 1.4 +/- 0.2, P < 0.05). Furthermore, superfusion of L-arginine (100 microM) caused an increase in capillary Lp (Ltestp/Lcontrolp = 2.4 +/- 0.9, P < 0.05), whereas D-arginine had no effect on Lp (Ltestp/Lcontrolp = 1.2 +/- 0.3). The results of this study support our hypothesis that inhibition of NO synthase decreases capillary Lp in the intact circulation. In addition, L-arginine increases capillary Lp in our model.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of stimulation of hepatic nerves on hepatic O2 uptake and blood flow

1977 ◽  
Vol 232 (6) ◽  
pp. H652-H656
Author(s):  
W. W. Lautt
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Oxygen Uptake ◽  
Portal Vein ◽  
Hepatic Artery ◽  
Venous Blood ◽  
Neurogenic Vasoconstriction ◽  
Pressure Changes ◽  
Hepatic Nerves ◽  
Stimulation Of

Acute denervation of the liver did not result in changes of oxygen uptake or hemodynamics in the intact liver of the cat. Stimulation of the hepatic nerves resulted in a marked reduction of vascular conductance of the hepatic artery and portal vein (intrahepatic) resulting in almost complete cessation of arterial flow and increased portal blood pressure. The hepatic artery showed a more complete escape from the neurogenic vasoconstriction than did the portal vein. During the stable "escape phase" oxygen delivery was 86% of control, but hepatic extraction of oxygen increased so that oxygen uptake was not altered from control values. The return of oxygen consumption to normal during nerve stimulation suggests that redistribution of hepatic blood flow did not occur. In spite of arterial and portal venous blood pressure changes and changes in gut conductance, oxygen extraction of the gut did not change.

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