Experimental selective elevation of renal medullary blood flow in hypertensive rats: evidence against short‐term hypotensive effect

Bądzyńska, Bożena; Sadowski, Janusz

doi:10.1111/j.1748-1716.2012.02435.x

Cited by 14 publications

(16 citation statements)

References 26 publications

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“…It was not certain if prolonged administration of bradykinin (Bk) would induce sustained elevation of MBF, even though in our earlier study the short‐term effect was quite distinct (Bądzyńska & Sadowski, ). However, in the present acute studies with each of the three rat hypertension models prolonged intramedullary Bk infusion effectively increased renal medullary perfusion.…”

Section: Discussionmentioning

confidence: 91%

“…This procedure (HS/UNX) was previously shown to result in the development of hypertension (Carlström et al . ; Bądzyńska & Sadowski, ).…”

Section: Methodsmentioning

confidence: 99%

“…The details of experimental procedures were as described earlier (Bądzyńska & Sadowski, , ). Briefly, mean arterial blood pressure (MAP) and heart rate (HR) were measured via a right femoral artery catheter connected with a Stoelting blood pressure meter (Stoelting, Wood Dale, IL, USA).…”

Section: Methodsmentioning

confidence: 99%

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Evidence against a crucial role of renal medullary perfusion in blood pressure control of hypertensive rats

Bądzyńska

Baranowska

Gawryś

et al. 2018

The Journal of Physiology

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Key points The development of new effective methods of treating arterial hypertension is hindered by uncertainty regarding its causes. According to one widespread concept hypertension is caused by abnormal blood circulation in the kidney, specifically by reduction of blood flow through the kidney medulla; however, this causal relationship has never been rigorously verified. We investigated whether in rats with three different forms of experimental hypertension prolonged selective elevation of renal medullary blood flow using local infusion of the vasodilator bradykinin would lower arterial pressure. We found that increasing medullary blood flow by almost 50% did not result in alleviation of hypertension, which argues against a causal role of such changes in the control of arterial pressure and suggests that attempts at improving renal medullary circulation are not likely to be a promising approach to combating hypertension. Abstract The crucial role of renal medullary blood flow (MBF) in the control of arterial pressure (MAP) has been widely accepted but not rigorously verified. We examined the effects of experimental selective MBF elevation on MAP, medullary tissue hypertonicity and renal excretion in hypertensive rats. We used three hypertensive rat models: (1) rats with hypertension induced by chronic angiotensin II infusions (AngII model), (2) rats with hypertension induced by unilateral nephrectomy followed by high salt diet (HS/UNX), and (3) spontaneously hypertensive rats (SHR). In acute experiments, MBF (laser‐Doppler measurement) was selectively increased with an intramedullary infusion of bradykinin (Bk) at 0.27 mg h−1 kg−1 BW over 4 h. MAP, renal artery blood flow (Transonic probe) and renal excretion parameters were measured simultaneously. In chronic studies with AngII and HS/UNX rats, Bk was infused over 2 weeks and MAP (telemetry probe) and renal excretion were repeatedly determined. In acute studies, with AngII, SHR and HS/UNX groups, Bk infusion caused a 47% increase in MBF (P < 0.01–0.001), whereas solvent infusion was without effect. During the experiments MAP decreased slightly and to the same extent with Bk and solvent infusion. Medullary tissue osmolality and [Na+] were lower in Bk‐ than in solvent‐infused AngII rats and in SHR. Two weeks of intramedullary Bk infusion tested in AngII and HS/UNX rats did not alter MAP or renal excretion; though in the latter group a significant MBF increase and medullary hypertonicity decrease was observed. Since no decrease in MAP in hypertensive rats was seen with Bk‐induced major renal medullary hyperperfusion or with a wash‐out of medullary solutes, our data argue against a crucial role of MBF in the pathogenesis of arterial hypertension.

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Section: Discussionmentioning

confidence: 91%

“…This procedure (HS/UNX) was previously shown to result in the development of hypertension (Carlström et al . ; Bądzyńska & Sadowski, ).…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Evidence against a crucial role of renal medullary perfusion in blood pressure control of hypertensive rats

Bądzyńska

Baranowska

Gawryś

et al. 2018

The Journal of Physiology

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“…, Dobrowolski & Sadowski , Seeliger et al . , Badzynska & Sadowski , , Jensen et al . , Warner et al .…”

Section: Renal Perfusion and Oxygenationunclassified

Linking non‐invasive parametric MRI with invasive physiological measurements (MR‐PHYSIOL): towards a hybrid and integrated approach for investigation of acute kidney injury in rats

et al. 2013

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Acute kidney injury of various origins shares a common link in the pathophysiological chain of events: imbalance between renal medullary oxygen delivery and oxygen demand. For in vivo assessment of kidney haemodynamics and oxygenation in animals, quantitative but invasive physiological methods are established. A very limited number of studies attempted to link these invasive methods with parametric Magnetic Resonance Imaging (MRI) of the kidney. Moreover, the validity of parametric MRI (pMRI) as a surrogate marker for renal tissue perfusion and renal oxygenation has not been systematically examined yet. For this reason, we set out to combine invasive techniques and non-invasive MRI in an integrated hybrid setup (MR-PHYSIOL) with the ultimate goal to calibrate, monitor and interpret parametric MR and physiological parameters by means of standardized interventions. Here we present a first report on the current status of this multi-modality approach. For this purpose, we first highlight key characteristics of renal perfusion and oxygenation. Second, concepts for in vivo characterization of renal perfusion and oxygenation are surveyed together with the capabilities of MRI for probing blood oxygenation-dependent tissue stages. Practical concerns evoked by the use of strong magnetic fields in MRI and interferences between MRI and invasive physiological probes are discussed. Technical solutions that balance the needs of in vivo physiological measurements together with the constraints dictated by small bore MR scanners are presented. An early implementation of the integrated MR-PHYSIOL approach is demonstrated including brief interventions of hypoxia and hyperoxia.

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“…, Zou & Cowley ). At any rate, however important NO may be for keeping an adequate medullary blood flow, forcefully increasing the medullary perfusion does not acutely normalize blood pressure levels in hypertensive animals (Bądzyńska & Sadowski ).…”

mentioning

confidence: 99%

Nitric oxide and reactive oxygen species in renal medulla pathophysiology – so small yet so special: the renal medulla

2013

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Experimental selective elevation of renal medullary blood flow in hypertensive rats: evidence against short‐term hypotensive effect

Cited by 14 publications

References 26 publications

Evidence against a crucial role of renal medullary perfusion in blood pressure control of hypertensive rats

Evidence against a crucial role of renal medullary perfusion in blood pressure control of hypertensive rats

Linking non‐invasive parametric MRI with invasive physiological measurements (MR‐PHYSIOL): towards a hybrid and integrated approach for investigation of acute kidney injury in rats

Nitric oxide and reactive oxygen species in renal medulla pathophysiology – so small yet so special: the renal medulla

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