Interaction between nitric oxide and renal myogenic autoregulation in normotensive and hypertensive rats

2001 ◽  
Vol 79 (3) ◽  
pp. 238-245 ◽  
Author(s):  
Xuemei Wang ◽  
William A Cupples
Keyword(s):  
Nitric Oxide ◽  
Blood Pressure ◽  
Blood Flow ◽  
Renal Blood Flow ◽  
Wistar Rats ◽  
Fundamental Property ◽  
Brown Norway ◽  
Sprague Dawley ◽  
Spontaneously Hypertensive ◽  
Long Evans

Blood pressure fluctuates continuously throughout life and autoregulation is the primary mechanism that isolates the kidney from this fluctuation. Compared with Wistar rats, Brown Norway (B-N) rats display impaired renal myogenic autoregulation when blood pressure fluctuation is increased. They also are very susceptible to hypertension-induced renal injury. Because blockade of nitric oxide augments myogenic autoregulation in Wistar rats, we compared the response of the myogenic system in B-N rats to nitric oxide blockade with that of other strains [Wistar, Sprague-Dawley, Long-Evans, spontaneously hypertensive (SHR)]. Renal blood flow dynamics were assessed in isoflurane anesthetized rats before and after inhibition of nitric oxide synthase by Lω-nitro-arginine methyl-ester (L-NAME, 10 mg/kg, iv). Under control conditions, myogenic autoregulation in the B-N rats was weaker than in the other strains. Myogenic autoregulation was not augmented after L-NAME administration in the SHR, but was augmented in all the normotensive rats. The enhancement was significantly greater in B-N rats so that after L-NAME the efficiency of autoregulation did not differ among the strains. The data suggest that nitric oxide is involved in the impaired myogenic autoregulation seen in B-N rats. Furthermore, the similarity of response in Wistar, Long-Evans, and Sprague-Dawley rats suggests that modulation by nitric oxide is a fundamental property of renal myogenic autoregulation.Key words: renal blood flow, transfer function, dynamics, SHR, Wistar, Long-Evans, Sprague-Dawley, Brown-Norway, L-NAME.

20-HETE-mediated vasoconstriction by hemoglobin-O2 carrier in Sprague-Dawley but not Wistar rats

2005 ◽  
Vol 98 (3) ◽  
pp. 772-779 ◽  
Author(s):  
Andrew D. Baines ◽  
Patrick Ho
Keyword(s):  
Nitric Oxide ◽  
Blood Pressure ◽  
Blood Flow ◽  
Wistar Rats ◽  
Filtration Rate ◽  
Blood Substitutes ◽  
Sprague Dawley ◽  
Ringer Lactate ◽  
Sd Rats ◽  
Renal Vascular

Hypothetically either decreased nitric oxide (NO) or increased O2 could initiate 20-HETE-mediated vasoconstriction associated with hemoglobin-based blood substitutes (HBOC). To test this hypothesis, we infused Tm-Hb, an HBOC with low O2 affinity, into isoflurane-anesthetized Wistar (W) and Sprague-Dawley (SD) rats after exchanging 20% of their blood with Ringer lactate. For comparison we infused an equal amount of BSA or BSA with NG-nitro-l-arginine methyl ester (BSA+NAME). Tm-Hb increased blood pressure (BP) and renal vascular resistance (RVR) equally in W and SD rats. Renal blood flow (RBF; Doppler ultrasound) decreased. BSA decreased RVR and raised glomerular filtration rate. BSA+NAME raised BP, RVR, and GFR. HET0016, an inhibitor of 20-HETE production, blunted BP and RVR responses to Tm-Hb and BSA+NAME in SD but not W rats. Arterial O2 content with BSA was lower than with Tm-Hb but O2 delivery was 60% higher with BSA because of higher RBF. BSA raised Po2 (Oxylite) in cortex and medulla and reduced RVR. Tm-Hb decreased Po2 and increased RVR. Switching rats from breathing air to 100% O2 raised intrarenal Po2 two- to threefold and increased BP and RVR. HET0016 did not alter hyperoxic responses. In conclusion, 20-HETE contributes to vasoconstriction by Tm-Hb in SD but not in W rats, and increased 20-HETE activity results primarily from decreased NO.

scholarly journals Blood pressure-renal blood flow relationships in conscious angiotensin II- and phenylephrine-infused rats

2013 ◽  
Vol 305 (7) ◽  
pp. F1074-F1084 ◽  
Author(s):  
Aaron J. Polichnowski ◽  
Karen A. Griffin ◽  
Jianrui Long ◽  
Geoffrey A. Williamson ◽  
Anil K. Bidani
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Renal Blood Flow ◽  
Function Analysis ◽  
Heart Beat ◽  
Ang Ii ◽  
Sprague Dawley ◽  
Renal Vasculature ◽  
Conscious Rats ◽  
Transfer Function Analysis

Chronic ANG II infusion in rodents is widely used as an experimental model of hypertension, yet very limited data are available describing the resulting blood pressure-renal blood flow (BP-RBF) relationships in conscious rats. Accordingly, male Sprague-Dawley rats ( n = 19) were instrumented for chronic measurements of BP (radiotelemetry) and RBF (Transonic Systems, Ithaca, NY). One week later, two or three separate 2-h recordings of BP and RBF were obtained in conscious rats at 24-h intervals, in addition to separate 24-h BP recordings. Rats were then administered either ANG II ( n = 11, 125 ng·kg−1·min−1) or phenylephrine (PE; n = 8, 50 mg·kg−1·day−1) as a control, ANG II-independent, pressor agent. Three days later the BP-RBF and 24-h BP recordings were repeated over several days. Despite similar increases in BP, PE led to significantly greater BP lability at the heart beat and very low frequency bandwidths. Conversely, ANG II, but not PE, caused significant renal vasoconstriction (a 62% increase in renal vascular resistance and a 21% decrease in RBF) and increased variability in BP-RBF relationships. Transfer function analysis of BP (input) and RBF (output) were consistent with a significant potentiation of the renal myogenic mechanism during ANG II administration, likely contributing, in part, to the exaggerated reductions in RBF during periods of BP elevations. We conclude that relatively equipressor doses of ANG II and PE lead to greatly different ambient BP profiles and effects on the renal vasculature when assessed in conscious rats. These data may have important implications regarding the pathogenesis of hypertension-induced injury in these models of hypertension.

Nitric oxide synthase and cGMP-mediated stimulation of renin secretion

2001 ◽  
Vol 281 (4) ◽  
pp. R1146-R1151 ◽  
Author(s):  
Cecilia M. Sayago ◽  
William H. Beierwaltes
Keyword(s):  
Nitric Oxide ◽  
Blood Pressure ◽  
Blood Flow ◽  
Nitric Oxide Synthase ◽  
Renal Blood Flow ◽  
No Synthase ◽  
Renin Secretion ◽  
Hemodynamic Changes ◽  
Oxide Synthase ◽  
Stimulation Of

The interaction between nitric oxide (NO) and renin is controversial. cAMP is a stimulating messenger for renin, which is degraded by phosphodiesterase (PDE)-3. PDE-3 is inhibited by cGMP, whereas PDE-5 degrades cGMP. We hypothesized that if endogenous cGMP was increased by inhibiting PDE-5, it could inhibit PDE-3, increasing endogenous cAMP, and thereby stimulate renin. We used the selective PDE-5 inhibitor zaprinast at 20 mg/kg body wt ip, which we determined would not change blood pressure (BP) or renal blood flow (RBF). In thiobutabarbital (Inactin)-anesthetized rats, renin secretion rate (RSR) was determined before and 75 min after administration of zaprinast or vehicle. Zaprinast increased cGMP excretion from 12.75 ± 1.57 to 18.67 ± 1.87 pmol/min ( P < 0.003), whereas vehicle had no effect. Zaprinast increased RSR sixfold (from 2.95 ± 1.74 to 17.62 ± 5.46 ng ANG I · h−1 · min−1, P< 0.024), while vehicle had no effect (from 4.08 ± 2.02 to 3.87 ± 1.53 ng ANG I · h−1 · min−1). There were no changes in BP or RBF. We then tested whether the increase in cGMP could be partially due to the activity of the neuronal isoform of NO synthase (nNOS). Pretreatment with the nNOS inhibitor 7-nitroindazole (7-NI; 50 mg/kg body wt) did not change BP or RBF but attenuated the renin-stimulating effect of zaprinast by 40% compared with vehicle. In 7-NI-treated animals, zaprinast-stimulated cGMP excretion was attenuated by 48%, from 9.17 ± 1.85 to 13.60 ± 2.15 pmol/min, compared with an increase from 10.94 ± 1.90 to 26.38 ± 3.61 pmol/min with zaprinast without 7-NI ( P < 0.04). This suggests that changes in endogenous cGMP production at levels not associated with renal hemodynamic changes are involved in a renin-stimulatory pathway. One source of this cGMP may be nNOS generation of NO in the kidney.

Effect of chronic renal medullary nitric oxide inhibition on blood pressure

1994 ◽  
Vol 266 (5) ◽  
pp. H1918-H1926 ◽  
Author(s):  
D. L. Mattson ◽  
S. Lu ◽  
K. Nakanishi ◽  
P. E. Papanek ◽  
A. W. Cowley
Keyword(s):  
Nitric Oxide ◽  
Blood Pressure ◽  
Blood Flow ◽  
Renal Medulla ◽  
Sodium Balance ◽  
Sprague Dawley ◽  
Nitric Oxide Inhibition ◽  
Medullary Blood Flow ◽  
Nitric Oxide Inhibitor ◽  
Oxide Inhibition

The effects of chronic nitric oxide inhibition in the renal medulla on renal cortical and medullary blood flow, sodium balance, and blood pressure were evaluated in conscious uninephrectomized Sprague-Dawley rats. During a 5-day renal medullary interstitial infusion of the nitric oxide inhibitor NG-nitro-L-arginine methyl ester (L-NAME, 120 micrograms/h) in saline (0.5 ml/min), renal medullary blood flow was selectively decreased by 30% after 2 h and was maintained at that level for the entire infusion. The decrease in medullary blood flow was associated with sodium retention and increased blood pressure. After the cessation of L-NAME infusion, medullary blood flow returned to control, and the sodium balance became negative as blood pressure returned to baseline. These data indicate that renal medullary nitric oxide plays an important role in the regulation of renal blood flow, sodium excretion, and blood pressure.

Responses of mesenteric and renal blood flow dynamics to acute denervation in anesthetized rats

1998 ◽  
Vol 275 (5) ◽  
pp. R1543-R1552 ◽  
Author(s):  
Isam Abu-Amarah ◽  
David O. Ajikobi ◽  
Hélène Bachelard ◽  
William A. Cupples ◽  
Fred C. Salevsky
Keyword(s):  
Blood Flow ◽  
Renal Blood Flow ◽  
Wistar Rats ◽  
Function Analysis ◽  
Renal Nerves ◽  
Dynamic Regulation ◽  
Spontaneously Hypertensive ◽  
Renal Autoregulation ◽  
Transfer Function Analysis ◽  
Blood Flow Dynamics

Previous studies have shown that renal autoregulation dynamically stabilizes renal blood flow (RBF). The role of renal nerves, particularly of a baroreflex component, in dynamic regulation of RBF remains unclear. The relative roles of autoregulation and mesenteric nerves in dynamic regulation of blood flow in the superior mesenteric artery (MBF) are similarly unclear. In this study, transfer function analysis was used to identify autoregulatory and baroreflex components in the dynamic regulation of RBF and MBF in Wistar rats and young spontaneously hypertensive rats (SHR) anesthetized with isoflurane or halothane. Wistar rats showed effective dynamic autoregulation of both MBF and RBF, as did SHR. Autoregulation was faster in the kidney (0.22 ± 0.01 Hz) than in the gut (0.13 ± 0.01 Hz). In the mesenteric, but not the renal bed, the admittance phase was significantly negative between 0.25 and 0.7 Hz, and the negative phase was abrogated by mesenteric denervation, indicating the presence of an arterial baroreflex. The baroreflex was faster than autoregulation in either bed. The presence of sympathetic effects unrelated to blood pressure was inferred in both vascular beds and appeared to be stronger in the SHR than in the Wistar rats. It is concluded that a physiologically significant baroreflex operates on the mesenteric, but not the renal circulation and that blood flow in both beds is effectively stabilized by autoregulation.

Ultrastructural Investigation of Spontaneous Pituitary Adenomas in Aging Sprague-Dawley Rats

1982 ◽  
Vol 40 ◽  
pp. 216-217
Author(s):  
D. J. McComb ◽  
J. Beri ◽  
F. Zak ◽  
K. Kovacs
Keyword(s):  
Microscopic Study ◽  
Pituitary Adenomas ◽  
Wistar Rats ◽  
Microscopic Level ◽  
Sprague Dawley ◽  
Prolactin Cells ◽  
Light Microscopic Level ◽  
Ultrastructural Investigation ◽  
Sprague Dawley Rats ◽  
Long Evans

Investigation of the spontaneous pituitary adenomas in rat have been limited mainly to light microscopic study. Furth et al. (1973) described them as chromophobic, secreting prolactin. Kovacs et al. (1977) in an ul trastructural investigation of adenomas of old female Long-Evans rats, found that they were composed of prolactin cells. Berkvens et al. (1980) using immunocytochemistry at the light microscopic level, demonstrated that some spontaneous tumors of old Wistar rats could contain GH, TSH or ACTH as well as PRL.

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