Losartan increases renal blood flow during isoflurane anesthesia in sheep

Ullman, Johan; Eriksson, Sven V.; Rundgren, Mats

doi:10.1034/j.1399-6576.2001.450919.x

Cited by 15 publications

(9 citation statements)

References 36 publications

(50 reference statements)

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“…Indeed, RBF is reduced under anesthesia in rabbits and humans (5,23), and in sheep, we find that isoflurane anesthesia reduces RBF by 30 -50% (10). Anesthesia might also be expected to enhance the workload of the loop of Henle, through activation of renal sympathetic nerve activity and the renin-angiotensin system (34,36,37,40). Together, these factors may account for the low medullary tPO 2 measured in some studies.…”

Section: Discussionmentioning

confidence: 83%

Long-term measurement of renal cortical and medullary tissue oxygenation and perfusion in unanesthetized sheep

Calzavacca

Evans

Bailey

et al. 2015

American Journal of Physiology-Regulatory, Integrative and Comp

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Calzavacca P, Evans RG, Bailey M, Lankadeva YR, Bellomo R, May CN. Long-term measurement of renal cortical and medullary tissue oxygenation and perfusion in unanesthetized sheep. Am J Physiol Regul Integr Comp Physiol 308: R832-R839, 2015. First published March 11, 2015 doi:10.1152/ajpregu.00515.2014.-The role of renal cortical and medullary hypoxia in the development of acute kidney injury is controversial, partly due to a lack of techniques for the long-term measurement of intrarenal oxygenation and perfusion in conscious animals. We have, therefore, developed a methodology to chronically implant combination probes to chronically measure renal cortical and medullary tissue perfusion and oxygen tension (tPO2) in conscious sheep and evaluated their responsiveness and reliability. A transit-time flow probe and a vascular occluder were surgically implanted on the left renal artery. At the same operation, dual fiber-optic probes, comprising a fluorescence optode to measure tPO2 and a laser-Doppler probe to assess tissue perfusion, were inserted into the renal cortex and medulla. In recovered conscious sheep (n ϭ 8) breathing room air, mean 24-h cortical and medullary tPO 2 were similar (31.4 Ϯ 0.6 and 29.7 Ϯ 0.7 mmHg, respectively). In the renal cortex and medulla, a 20% reduction in renal blood flow (RBF) decreased perfusion (14.6 Ϯ 8.6 and 41.2 Ϯ 8.5%, respectively) and oxygenation (48.1 Ϯ 8.5 and 72.4 Ϯ 8.5%, respectively), with greater decreases during a 50% reduction in RBF. At autopsy, minimal fibrosis was observed around the probes. In summary, we have developed a technique to chronically implant fiber-optic probes in the renal cortex and medulla for recording tissue perfusion and oxygenation over many days. In normal resting conscious sheep, cortical and medullary tPO 2 were similar. The responses to and recovery from renal artery occlusion, together with the consistent measurements over a 24-h period, demonstrate the responsiveness and stability of the probes. renal blood flow; kidney oxygenation; renal artery occlusion; perfusion; tissue oxygen tension.THE ETIOLOGY OF RENAL FAILURE is highly dependent on the setting in which it occurs. Nevertheless, considerable interest has focused on the potential for renal tissue hypoxia to provide a common pathway in multiple forms of acute and chronic kidney disease (18). Oxygen supply to the kidney via the renal artery far exceeds the kidney's metabolic requirements, yet the renal medulla, in particular, appears susceptible to the development of hypoxia (8).Many studies in which medullary tissue PO 2 (tPO 2 ) has been measured by polarographic electrodes in experimental animals and humans, breathing air or gas mixtures enriched in oxygen, have provided values of 10 -20 mmHg (4,8,9,11,25), close to the critical tPO 2 for isolated tubular cells (5 to 15 mmHg) (2, 3, 13, 14). These observations have led to the concept that the medulla normally operates on the brink of hypoxia and so is highly susceptible to factors that might reduce oxygen delivery or increase oxygen...

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Section: Discussionmentioning

confidence: 83%

Long-term measurement of renal cortical and medullary tissue oxygenation and perfusion in unanesthetized sheep

Calzavacca

Evans

Bailey

et al. 2015

American Journal of Physiology-Regulatory, Integrative and Comp

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“…In addition, the protective role of vitamin E supplementation against CP-induced peripheral neuropathy in patients was evaluated, and its neuroprotective role was reported [36, 37]. Although vitamins C and E and losartan have antioxidant effects [22, 23, 38, 39], losartan itself acts as a blocker of angiotensin II receptor 1 (ATR1), which facilitates renal circulation [40, 41]. The protective effect of losartan against CP-induced nephrotoxicity was reported before [5, 6], and it has no effect on CP uptake by the kidney [6].…”

Section: Introductionmentioning

confidence: 99%

Vitamin E, Vitamin C, or Losartan Is Not Nephroprotectant against Cisplatin-Induced Nephrotoxicity in Presence of Estrogen in Ovariectomized Rat Model

Nematbakhsh

Pezeshki

Eshraghi-Jazi

et al. 2012

International Journal of Nephrology

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Background. The nephroprotective effect of vitamins E and C or losartan against cisplatin (CP)- induced nephrotoxicity when they are accompanied by estrogen was investigated. Methods. The ovariectomized rats received estradiol valerate for two weeks. At the end of the first week, a single dose of CP (7 mg/kg, IP) was also administered, and they received placebo (group 1), vitamin E (group 2), vitamin C (group 3), or losartan (group 4) every day during the second week, and they were compared with another three control groups. Results. CP alone increased the serum levels of blood urea nitrogen (BUN), creatinine (Cr), and kidney tissue damage score (KTDS), significantly (P < 0.05), however at the presence of estradiol and CP, vitamin C, vitamin E, or losartan not only did not decrease these parameters, but also increased them significantly (P < 0.05). The serum level of superoxidase dismutase (SOD) was reduced by CP (P < 0.05), but it was increased when estradiol or estradiol plus vitamin C or losartan were added (P < 0.05). Conclusion. The particular pharmacological dose of estrogen used in this study abolish the nephroprotective effects vitamins C and E or losartan against CP-induced nephrotoxicity.

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“…In view of these data, volatile anesthetics may be postulated to have a role in counteracting septic AKI development. However, these agents also reduce urine output, glomerular filtration and renal blood flow (RBF), 13,14 which instead suggests that volatile anesthetics may reinforce the development of AKI during sepsis.…”

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confidence: 99%

The effects of isoflurane anesthesia and mechanical ventilation on renal function during endotoxemia

Frithiof

Soehnlein

Eriksson

et al. 2011

Acta Anaesthesiologica Scandinavica

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Losartan increases renal blood flow during isoflurane anesthesia in sheep

Cited by 15 publications

References 36 publications

Long-term measurement of renal cortical and medullary tissue oxygenation and perfusion in unanesthetized sheep

Long-term measurement of renal cortical and medullary tissue oxygenation and perfusion in unanesthetized sheep

Vitamin E, Vitamin C, or Losartan Is Not Nephroprotectant against Cisplatin-Induced Nephrotoxicity in Presence of Estrogen in Ovariectomized Rat Model

The effects of isoflurane anesthesia and mechanical ventilation on renal function during endotoxemia

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