Regulation of renal hemodynamics after protein feeding: effects of loop diuretics

Woods, L. L.; DeYoung, D. R.; Smith, Brendan E.

doi:10.1152/ajprenal.1991.261.5.f815

Cited by 16 publications

(17 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A similar value for P LL was revealed in intact rats after furosemide, suggesting that the SAD procedure did not alter the effect of furosemide on RBF autoregulation. An impairment of RBF autoregulation after furosemide has been previously reported in conscious dogs by using stepwise AP reductions from spontaneous AP (16,25,26). However, in these experiments, a new value for P LL could not be estimated, because an autoregulatory plateau could not be determined.…”

Section: Discussionmentioning

confidence: 87%

“…AUTOREGULATION OF TOTAL RENAL blood flow (RBF) is usually explored by measuring RBF responses to externally induced stepwise reductions of arterial pressure (AP) in both anesthetized (6,8,11,13,17,21,22) and conscious (2,4,16,18,(24)(25)(26) animals. Steady-state levels of RBF are plotted as a function of AP, which allows the drawing of autoregulation curves from which the plateau and lower pressure limit of RBF autoregulation (P LL ) are estimated.…”

mentioning

confidence: 99%

“…With the use of stepwise reductions of AP, it has been shown that blockade of tubuloglomerular feedback (TGF) activity results in a significant impairment of RBF autoregulation (8,16,25,26), suggesting that the autoregulatory efficiency is dependent on the TGF mechanism. However, using spectral analysis of AP and RBF in conscious dogs, it has also been reported that the TGF mechanism was not required for RBF autoregulation in response to spontaneously occurring AP changes (16).…”

mentioning

confidence: 99%

See 2 more Smart Citations

Spontaneous renal blood flow autoregulation curves in conscious sinoaortic baroreceptor-denervated rats

Pires

Julien

Chapuis

et al. 2002

American Journal of Physiology-Renal Physiology

View full text Add to dashboard Cite

Pires, Silene L. S., Claude Julien, Bruno Chapuis, Jean Sassard, and Christian Barrè s. Spontaneous renal blood flow autoregulation curves in conscious sinoaortic baroreceptor-denervated rats. Am J Physiol Renal Physiol 282: F51-F58, 2002. First published August 8, 2001 10.1152/ajprenal.00186.2001.-These experiments examined whether the conscious sinoaortic baroreceptor-denervated (SAD) rat, owing to its high spontaneous arterial pressure (AP) variability, might represent a model for renal blood flow (RBF) autoregulation studies. In eight SAD and six baroreceptor-intact rats, AP and RBF were recorded (1-h periods) before and after furosemide (10 mg/kg followed by 10 mg ⅐ kg Ϫ1 ⅐ h Ϫ1 iv) administration. In control conditions, AP variability was markedly enhanced in SAD rats (coefficient of variation: 16.0 Ϯ 1.2 vs. 5.4 Ϯ 0.5% in intact rats), whereas RBF variability was only slightly increased (8.7 Ϯ 0.6 vs. 6.1 Ϯ 0.5% in intact rats), suggesting buffering by autoregulatory mechanisms. In SAD rats, but not in intact rats, the AP-RBF relationships could be modeled with a four-parameter sigmoid Weibull equation (r 2 ϭ 0.24 Ϯ 0.07, 3,600 data pairs/rat), allowing for estimation of an autoregulatory plateau (10.1 Ϯ 0.7 ml/min) and a lower limit of RBF autoregulation (PLL ϭ 93 Ϯ 6 mmHg, defined as AP at RBF 5% below the plateau). After furosemide treatment, autoregulation curves (r 2 ϭ 0.49 Ϯ 0.07) in SAD rats were shifted downward (plateau ϭ 8.6 Ϯ 0.8 ml/min) and rightward (PLL ϭ 102 Ϯ 5 mmHg). In five of six intact rats, PLL became measurable (104 Ϯ 1 mmHg), albeit with limited accuracy (r 2 ϭ 0.09 Ϯ 0.03). In conclusion, the conscious SAD rat offers the possibility of describing RBF autoregulation curves under dynamic, unforced conditions. The tubuloglomerular feedback and myogenic mechanisms cooperate in setting PLL and thus in stabilizing RBF during spontaneous depressor episodes.arterial pressure variability; furosemide; modeling AUTOREGULATION OF TOTAL RENAL blood flow (RBF) is usually explored by measuring RBF responses to externally induced stepwise reductions of arterial pressure (AP) in both anesthetized (6,8,11,13,17,21,22) and conscious (2,4,16,18,(24)(25)(26) animals. Steady-state levels of RBF are plotted as a function of AP, which allows the drawing of autoregulation curves from which the plateau and lower pressure limit of RBF autoregulation (P LL ) are estimated. It is not known whether such information can be gained under spontaneous unforced conditions, i.e., using RBF responses to naturally occurring AP fluctuations.The conscious sinoaortic baroreceptor-denervated (SAD) rat is a well-recognized model of exaggerated AP variability, which is characterized by the spontaneous occurrence of pressor and depressor episodes of occasionally large amplitude (3,28). Recently, we have investigated in conscious SAD rats the relationships between AP variability and RBF variability (20). Although AP variability was markedly increased, RBF variability was only slightly increased, suggesting a powerful participa...

show abstract

Section: Discussionmentioning

confidence: 87%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Spontaneous renal blood flow autoregulation curves in conscious sinoaortic baroreceptor-denervated rats

Pires

Julien

Chapuis

et al. 2002

American Journal of Physiology-Renal Physiology

View full text Add to dashboard Cite

show abstract

“…Autoregulation was less complete after inhibition of MD-TGF by genetic deletion of adenosine A 1 receptors (583,751) or P 2 X 1 receptors (686) or Cx40 (756,1395), all of which impair MD-TGF responses. Glomerular autoregulation has been reported to be less efficient in the absence of MD-TGF in several species, including rats (1019,1022,1313,1444), dogs (351, 760,1064,1090,1091,1622), and mice (583). For example, the MD-TGF in the rat contributed ϳ50% to autoregulation of SNGFR when the RPP was reduced from 115 to 95 mmHg and 30% when it was reduced from 95 to 80 mmHg (1313).…”

Section: Conventional Macula Densa Tubuloglomerular Feedbackmentioning

confidence: 99%

Renal Autoregulation in Health and Disease

Carlström

Wilcox

Arendshorst

2015

Physiological Reviews

384

383

View full text Add to dashboard Cite

Intrarenal autoregulatory mechanisms maintain renal blood flow (RBF) and glomerular filtration rate (GFR) independent of renal perfusion pressure (RPP) over a defined range (80-180 mmHg). Such autoregulation is mediated largely by the myogenic and the macula densa-tubuloglomerular feedback (MD-TGF) responses that regulate preglomerular vasomotor tone primarily of the afferent arteriole. Differences in response times allow separation of these mechanisms in the time and frequency domains. Mechanotransduction initiating the myogenic response requires a sensing mechanism activated by stretch of vascular smooth muscle cells (VSMCs) and coupled to intracellular signaling pathways eliciting plasma membrane depolarization and a rise in cytosolic free calcium concentration ([Ca(2+)]i). Proposed mechanosensors include epithelial sodium channels (ENaC), integrins, and/or transient receptor potential (TRP) channels. Increased [Ca(2+)]i occurs predominantly by Ca(2+) influx through L-type voltage-operated Ca(2+) channels (VOCC). Increased [Ca(2+)]i activates inositol trisphosphate receptors (IP3R) and ryanodine receptors (RyR) to mobilize Ca(2+) from sarcoplasmic reticular stores. Myogenic vasoconstriction is sustained by increased Ca(2+) sensitivity, mediated by protein kinase C and Rho/Rho-kinase that favors a positive balance between myosin light-chain kinase and phosphatase. Increased RPP activates MD-TGF by transducing a signal of epithelial MD salt reabsorption to adjust afferent arteriolar vasoconstriction. A combination of vascular and tubular mechanisms, novel to the kidney, provides for high autoregulatory efficiency that maintains RBF and GFR, stabilizes sodium excretion, and buffers transmission of RPP to sensitive glomerular capillaries, thereby protecting against hypertensive barotrauma. A unique aspect of the myogenic response in the renal vasculature is modulation of its strength and speed by the MD-TGF and by a connecting tubule glomerular feedback (CT-GF) mechanism. Reactive oxygen species and nitric oxide are modulators of myogenic and MD-TGF mechanisms. Attenuated renal autoregulation contributes to renal damage in many, but not all, models of renal, diabetic, and hypertensive diseases. This review provides a summary of our current knowledge regarding underlying mechanisms enabling renal autoregulation in health and disease and methods used for its study.

show abstract

“…Some information concerning the mechanisms of autoregulation can be inferred by use of agents known to specifically affect one component of autoregulation, e.g., furosemide, which effectively blocks the TGF mechanism (168,217). Recently, a note of caution has been introduced by the demonstration that loop diuretics can also inhibit myogenic responsiveness directly (212) and, in general, the selectivity of inhibitors tends to decline with time.…”

Section: General Considerations When Renal Autoregulation Is Assessedmentioning

confidence: 99%

Assessment of renal autoregulation

Cupples¹,

Braam²

2007

American Journal of Physiology-Renal Physiology

170

188

View full text Add to dashboard Cite

The kidney displays highly efficient autoregulation so that under steady-state conditions renal blood flow (RBF) is independent of blood pressure over a wide range of pressure. Autoregulation occurs in the preglomerular microcirculation and is mediated by two, perhaps three, mechanisms. The faster myogenic mechanism and the slower tubuloglomerular feedback contribute both directly and interactively to autoregulation of RBF and of glomerular capillary pressure. Multiple experiments have been used to study autoregulation and can be considered as variants of two basic designs. The first measures RBF after multiple stepwise changes in renal perfusion pressure to assess how a biological condition or experimental maneuver affects the overall pressure-flow relationship. The second uses time-series analysis to better understand the operation of multiple controllers operating in parallel on the same vascular smooth muscle. There are conceptual and experimental limitations to all current experimental designs so that no one design adequately describes autoregulation. In particular, it is clear that the efficiency of autoregulation varies with time and that most current techniques do not adequately address this issue. Also, the time-varying and nonadditive interaction between the myogenic mechanism and tubuloglomerular feedback underscores the difficulty of dissecting their contributions to autoregulation. We consider the modulation of autoregulation by nitric oxide and use it to illustrate the necessity for multiple experimental designs, often applied iteratively.

show abstract

Regulation of renal hemodynamics after protein feeding: effects of loop diuretics

Cited by 16 publications

References 0 publications

Spontaneous renal blood flow autoregulation curves in conscious sinoaortic baroreceptor-denervated rats

Spontaneous renal blood flow autoregulation curves in conscious sinoaortic baroreceptor-denervated rats

Renal Autoregulation in Health and Disease

Assessment of renal autoregulation

Contact Info

Product

Resources

About