Survival in Hostile Environments: Strategies of Renal Medullary Cells

Physiology ◽  
2006 ◽  
Vol 21 (3) ◽  
pp. 171-180 ◽  
Author(s):  
Wolfgang Neuhofer ◽  
Franz-X. Beck
Keyword(s):  
Reactive Oxygen Species ◽  
Reactive Oxygen ◽  
Renal Medulla ◽  
Extreme Conditions ◽  
Oxygen Species ◽  
Low Oxygen ◽  
Oxygen Tensions ◽  
Hostile Environments ◽  
Medullary Cells

Cells in the renal medulla exist in a hostile milieu characterized by wide variations in extracellular solute concentrations, low oxygen tensions, and abundant reactive oxygen species. This article reviews the strategies adopted by these cells to allow them to survive and fulfill their functions under these extreme conditions.

scholarly journals Scavenging reactive oxygen species mimics the anoxic response in goldfish pyramidal neurons

2021 ◽  
Author(s):  
Varshinie Pillai ◽  
Leslie Buck ◽  
Ebrahim Lari
Keyword(s):  
Reactive Oxygen Species ◽  
Action Potential ◽  
Pyramidal Neurons ◽  
Reactive Oxygen ◽  
Severe Hypoxia ◽  
Oxygen Species ◽  
Low Oxygen ◽  
Ros Scavenging ◽  
Patch Clamp Recording ◽  
Whole Cell

Goldfish are one of a few species able to avoid cellular damage during month-long periods in severely hypoxic environments. By suppressing action potentials in excitatory glutamatergic neurons, the goldfish brain decreases its overall energy expenditure. Co-incident with reductions in O2 availability is a natural decrease in cellular reactive oxygen species (ROS) generation, which has been proposed to function as part of a low oxygen signal transduction pathway. Therefore, using live-tissue fluorescence microscopy, we found that ROS production decreased by 10% with the onset of anoxia in goldfish telencephalic brain slices. Employing whole-cell patch-clamp recording, we found that like severe hypoxia the ROS scavengers N-acetyl cysteine (NAC) and MitoTEMPO, added during normoxic periods, depolarized membrane potential (severe hypoxia -73.6 to – 61.4 mV; NAC -76.6 to -66.2 mV; and MitoTEMPO -71.5 mV to -62.5 mV) and increased whole-cell conductance (severe hypoxia 5.7 to 8.0 nS; NAC 6 nS to 7.5 nS; and MitoTEMPO 6.0 nS to 7.6 nS). Also, in a subset of active pyramidal neurons these treatments reduced action potential firing frequency (severe hypoxia 0.18 Hz to 0.03 Hz; NAC 0.27 Hz to 0.06 Hz and MitoTEMPO 0.35 Hz to 0.08 Hz ). Neither severe hypoxia nor ROS scavenging impacted action potential threshold. The addition of exogenous hydrogen peroxide could reverse the effects of the antioxidants. Taken together, this supports a role for a reduction in [ROS] as a low oxygen signal in goldfish brain.

scholarly journals Reactive oxygen species as important determinants of medullary flow, sodium excretion, and hypertension

2015 ◽  
Vol 308 (3) ◽  
pp. F179-F197 ◽  
Author(s):  
Allen W. Cowley ◽  
Michiaki Abe ◽  
Takefumi Mori ◽  
Paul M. O'Connor ◽  
Yusuke Ohsaki ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Reactive Oxygen Species ◽  
Hydrogen Peroxide ◽  
Blood Flow ◽  
Reactive Oxygen ◽  
Selective Reduction ◽  
Renal Medulla ◽  
Thick Ascending Limb ◽  
Oxygen Species ◽  
Medullary Blood Flow

The physiological evidence linking the production of superoxide, hydrogen peroxide, and nitric oxide in the renal medullary thick ascending limb of Henle (mTAL) to regulation of medullary blood flow, sodium homeostasis, and long-term control of blood pressure is summarized in this review. Data obtained largely from rats indicate that experimentally induced elevations of either superoxide or hydrogen peroxide in the renal medulla result in reduction of medullary blood flow, enhanced Na+ reabsorption, and hypertension. A shift in the redox balance between nitric oxide and reactive oxygen species (ROS) is found to occur naturally in the Dahl salt-sensitive (SS) rat model, where selective reduction of ROS production in the renal medulla reduces salt-induced hypertension. Excess medullary production of ROS in SS rats emanates from the medullary thick ascending limbs of Henle [from both the mitochondria and membrane NAD(P)H oxidases] in response to increased delivery and reabsorption of excess sodium and water. There is evidence that ROS and perhaps other mediators such as ATP diffuse from the mTAL to surrounding vasa recta capillaries, resulting in medullary ischemia, which thereby contributes to hypertension.

Effects of Low Oxygen Condition on the Generation of Reactive Oxygen Species and the Development in Mouse Embryos Culturedin vitro

1999 ◽  
Vol 25 (5) ◽  
pp. 359-366 ◽  
Author(s):  
Hyuck-Chan Kwon ◽  
Hyun-Won Yang ◽  
Kyung-Joo Hwang ◽  
Jung-Hyun Yoo ◽  
Myung-Sin Kim ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Reactive Oxygen ◽  
Mouse Embryos ◽  
Oxygen Species ◽  
Low Oxygen ◽  
Oxygen Condition

Induction ofPseudomonas aeruginosafhpandfhpRby reactive oxygen species

2009 ◽  
Vol 55 (6) ◽  
pp. 657-663 ◽  
Author(s):  
Taija S. Koskenkorva-Frank ◽  
Pauli T. Kallio
Keyword(s):  
Oxidative Stress ◽  
Reactive Oxygen Species ◽  
Hydrogen Peroxide ◽  
Promoter Activity ◽  
Reactive Oxygen ◽  
Oxygen Species ◽  
Low Oxygen ◽  
Butyl Hydroperoxide ◽  
Tert Butyl Hydroperoxide ◽  
Oxygen Conditions

In Pseudomonas aeruginosa , flavohemoglobin (Fhp) and its cognate regulator FhpR (PA2665) form a protective regulatory circuit, which responds to reactive nitrogen species and is also capable of protecting cells against nitrosative stress. Recently, it has been shown that the expression of the fhp promoter is regulated not only by FhpR, but also by two new regulators, PA0779 and PA3697. It has also been suggested that the bacterial flavohemoglobins (flavoHbs) could play a crucial role in the protection of cells against reactive oxygen species (ROS). Therefore, the role and function of the Fhp/FhpR system during oxidative stress were studied by assessing the viability and membrane integrity of P. aeruginosa cells and by analyzing the promoter activities of fhp and fhpR upon exposure to paraquat, hydrogen peroxide, and tert-butyl hydroperoxide, under both aerobic and low-oxygen conditions. The results showed that under aerobic conditions, both fhp and fhpR promoters are induced by ROS generated by the stressors. Thus, the Fhp/FhpR system is implicated in the oxidative stress response. ROS-induced fhp promoter activity was dependent on FhpR, PA0779, and PA3697 regulators. Tert-butyl hydroperoxide-induced fhpR promoter activity was found to be highly repressed by PA0779, and FhpR showed negative autoregulation of its own promoter. Under low-oxygen conditions, the activity of the fhp promoter was not inducible by ROS, but fhpR promoter activity was induced by paraquat, and hydrogen peroxide was repressed in both cases by the regulators PA0779 and PA3697.

High oxygen tension constricts epineurial arterioles of the rat sciatic nerve via reactive oxygen species

2007 ◽  
Vol 293 (3) ◽  
pp. H1498-H1507 ◽  
Author(s):  
Noriko Sakai ◽  
Risuke Mizuno ◽  
Nobuyuki Ono ◽  
Hiroyuki Kato ◽  
Toshio Ohhashi
Keyword(s):  
Reactive Oxygen Species ◽  
Sciatic Nerve ◽  
Reactive Oxygen ◽  
High Oxygen ◽  
Dependent Manner ◽  
Oxygen Species ◽  
Low Oxygen ◽  
Rat Sciatic Nerve ◽  
Sciatic Nerves

Microcirculation of the sheath of the rat sciatic nerve fiber was investigated by using an intravital microscope, and changes in the diameter of the epineurial arterioles in response to highly oxygenated Krebs-bicarbonate solution were evaluated. Superfusion of low-oxygen (0%) Krebs-bicarbonate solution (LKS) onto rat sciatic nerves did not affect changes in the diameter of the arterioles. Nifedipine, a Ca2+-channel blocker, caused a dose-dependent dilation of the epineurial arterioles in LKS. In contrast, superfusion of high-oxygen (21%) Krebs-bicarbonate solution (HKS) onto rat sciatic nerves significantly constricted the epineurial arterioles in a time-dependent manner. The HKS-induced constriction of the epineurial arterioles was significantly reduced by treatment with 120 U/ml superoxide dismutase (SOD) alone or 5,000 U/ml catalase alone. In the presence of 120 U/ml SOD plus 5,000 U/ml catalase, 10−4 M tempol, 10−6 M diphenyleneiodium, 2 × 10−4 M apocynin, or 10−6 M allopurinol, the HKS-induced constriction of the epineurial arterioles completely disappeared. These results suggest that superfusion of highly oxygenated solution onto rat sciatic nerves constricts the epineurial arterioles through reactive oxygen species (ROS), including superoxide and hydrogen peroxide, and that production of superoxide involves a NADPH oxidase- or xanthine oxidase-dependent pathway. In conclusion, ROS play significant roles in the regulation of microcirculation of rat sciatic nerves in vivo.

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