Association of Noise Annoyance with Measured Renal Hemodynamic Changes

<b><i>Background:</i></b> Chronic mental stress is recognized as a modifiable risk factor for cardiovascular disease. The aim of this study was to demonstrate that noise annoyance-induced stress is associated with changes in renal hemodynamics. <b><i>Methods:</i></b> Renal hemodynamic parameters were measured using steady-state input clearance with infusion of para-aminohippuric acid and inulin in individuals with normal, high normal, and elevated blood pressure. All individuals ranked subjective annoyance due to noise in everyday life on a 7-grade Likert scale. The median of all rankings was used as a cutoff point to divide the group into noise-annoyed and non-noise-annoyed individuals. Different renal hemodynamic parameters were calculated based on the Gomez equation. <b><i>Results:</i></b> Noise-annoyed individuals (<i>n</i> = 58) showed lower renal plasma flow (599 ± 106 vs. 663 ± 124 mL/min, <i>p</i> = 0.009), lower renal blood flow (1,068 ± 203 vs. 1,172 ± 225 mL/min, <i>p</i> = 0.047), higher filtration fraction (22.7 ± 3.3 vs. 21.3 ± 3.0, <i>p</i> = 0.012), higher renal vascular resistance (88.9 ± 25.6 vs. 75.8 ± 22.9 mm Hg/[mL/min], <i>p</i> = 0.002), and higher resistance of afferent arteriole (2,439.5 ± 1,253.4 vs. 1,849.9 ± 1,242.0 dyn s⁻¹ cm⁻⁵, <i>p</i> = 0.001) compared to non-noise-annoyed individuals (<i>n</i> = 55). There was no difference in measured glomerular filtration rate (133 ± 11.8 vs. 138 ± 15 mL/min, <i>p</i> = 0.181), resistance of efferent arteriole (2,419.4 ± 472.2 vs. 2,245.8 ± 370.3 dyn s⁻¹ cm⁻⁵, <i>p</i> = 0.060), and intraglomerular pressure (64.0 ± 3.1 vs. 64.6 ± 3.5 mm Hg, <i>p</i> = 0.298) between the groups. After adjusting for age, renal plasma flow, renal blood flow, and renal vascular resistance remained significantly different between the groups, with a trend in increased afferent arteriolar resistance and filtration fraction. <b><i>Conclusion:</i></b> In this study, noise annoyance was associated with reduced renal perfusion attributed to increased renal vascular resistance predominantly at the afferent site. Long-term consequences of this renal hemodynamic pattern due to noise annoyance need to be investigated.

Centrally acting cholecystokinin induces depressor circulatory effects in haemorrhage-shocked rats

WstępCholecystokinina (CCK) należy do hormonów peptydowych układu pokarmowego regulujących trawienie lipidów i białek, a ponadto jest ośrodkowym neurotransmiterem/neuromodulatorem. Po podaniu dożylnym wywołuje efekt resuscytacyjny u szczurów we wstrząsie krwotocznym. Ze względu na fakt, iż CCK może wpływać bezpośrednio i pośrednio na czynność ośrodka sercowo-naczyniowego, celem pracy było zbadanie działania pochodnej siarczanowej oktapeptydu CCK (CCK-8) podawanej do komory bocznej mózgu (<i>intracerebroventricularly</i> – icv) w fazie hamowania czynności układu współczulnego we wstrząsie krwotocznym.Materiał i metodyBadania przeprowadzono u samców szczurów szczepu Wistar w znieczuleniu ogólnym (ketamina [100 mg/kg]/ksylazyna [10 mg/kg]), u których wywołano nieodwracalny wstrząs krwotoczny (0% przeżycia 2 h) ze średnim ciśnieniem tętniczym (<i>mean arterial pressure</i> – MAP) 20–25 mmHg. W 5 min krytycznej hipotensji szczurom podawano icv CCK-8 (5, 15 nmol) lub 0,9% roztwór NaCl (5 μl).WynikiKrwotok prowadził do obniżenia ciśnienia tętna (<i>pulse pressu</i>re – PP), częstości rytmu serca (<i>heart rate</i> – HR) oraz wzrostu nerkowego (<i>renal vascular resistance</i> – RVR) i krezkowego oporu naczyniowego (<i>mesenteric vascular resistance</i> – MVR). W grupie kontrolnej nie stwierdzono wzrostu badanych parametrów układu krążenia, a średni czas przeżycia wynosił 32,5 ± 5,1 min. CCK-8 wywoływała zależne od dawki spadki MAP, PP i HR ze wzrostem RVR i MVR, a także skracała czas przeżycia w porównaniu ze zwierzętami kontrolnymi.WnioskiOśrodkowo działająca CCK-8 wywołuje działanie depresyjne na układ krążenia u szczurów we wstrząsie krwotocznym.

Abstract 12882: Renal Hemodynamics in Chronic Heart Failure With Preserved and Reduced Ejection Fraction

Introduction: Chronic heart failure (CHF) and impaired renal function are two co-existing medical conditions and known to be associated with adverse outcome. The cardiorenal interaction has not yet been analyzed thoroughly. The aim of this study was to assess renal and intraglomerular hemodynamics by constant infusion input clearance technique in subjects with CHF compared to healthy controls. Methods: This was a cross-sectional observational study including 85 subjects. The group of subjects with CHF consisted of 27 individuals with HFpEF and 27 individuals with HFrEF, who were compared to 31 controls. All subjects underwent renal clearance examination to determine measured -not estimated- glomerular filtration rate (GFR), renal blood and plasma flow (RBF, RPF) and to calculate renal hemodynamic parameters such as filtration fraction (FF), renal vascular resistance (RVR), intraglomerular pressure (P glom ) and resistances of the afferent (R A ) and efferent arterioles (R E ). Results: GFR was lower in subjects with CHF (88.6±13.1ml/min/1.73m 2 ) compared to controls (108.6±17. ml/min/1.73m 2 ) after adjustment for age and BP (p adj =0.037). There were no significant differences regarding RPF, RBF, FF, RVR, P glom , R A as well as R E after adjustment for age and BP. Similarly, there were no significant differences regarding renal hemodynamic parameters between HFpEF and HFrEF subjects. Bivariate correlation analysis in the group of subjects with CHF revealed an inverse association between NT-proBNP and RPF (R=-0.421, p=0.002), RBF (R=-0.414, p=0.002) and a positive association with FF (R=0.324, p=0.019), RVR (R=0.346, p=0.012) and R E (R=0.318, p=0.022). Conclusions: The findings of this study indicate that in CHF renal function is slightly reduced even though renal perfusion is preserved. With progressive severity of CHF as indicated by increasing NT-proBNP, renal vascular resistance in particular at the postglomerular side increases. Our data are in accordance with neuroendocrine activation in CHF since vasoconstriction at the postglomerular site points towards angiotensin II as mediator. The association between NT-proBNP and renal hemodynamics documents a close cardiorenal interaction in CHF.

Renal vascular resistance is increased in patients with kidney transplant

Background Despite improvement in short-term outcome of kidney transplants, the long-term survival of kidney transplants has not changed over past decades. Kidney biopsy is the gold standard of transplant pathology but it’s invasive. Quantification of transplant blood flow could provide a novel non-invasive method to evaluate transplant pathology. The aim of this retrospective cross-sectional pilot study was to evaluate positron emission tomography (PET) as a method to measure kidney transplant perfusion and find out if there is correlation between transplant perfusion and histopathology. Methods Renal cortical perfusion of 19 kidney transplantation patients [average time from transplantation 33 (17–54) months; eGFR 55 (47–69) ml/min] and 10 healthy controls were studied by [15 O]H2O PET. Perfusion and Doppler resistance index (RI) of transplants were compared with histology of one-year protocol transplant biopsy. Results Renal cortical perfusion of healthy control subjects and transplant patients were 2.7 (2.4–4.0) ml min− 1 g− 1 and 2.2 (2.0–3.0) ml min− 1 g− 1, respectively (p = 0.1). Renal vascular resistance (RVR) of the patients was 47.0 (36.7–51.4) mmHg mL− 1min− 1g− 1 and that of the healthy 32.4 (24.6–39.6) mmHg mL− 1min−1g−1 (p = 0.01). There was a statistically significant correlation between Doppler RI and perfusion of transplants (r = − 0.51, p = 0.026). Transplant Doppler RI of the group of mild fibrotic changes [0.73 (0.70–0.76)] and the group of no fibrotic changes [0.66 (0.61–0.72)] differed statistically significantly (p = 0.03). No statistically significant correlation was found between cortical perfusion and fibrosis of transplants (p = 0.56). Conclusions [15 O]H2O PET showed its capability as a method in measuring perfusion of kidney transplants. RVR of transplant patients with stage 2–3 chronic kidney disease was higher than that of the healthy, although kidney perfusion values didn’t differ between the groups. Doppler based RI correlated with perfusion and fibrosis of transplants.

Losartan does not decrease renal oxygenation and norepinephrine effects in rats after resuscitated hemorrhage

Renin-angiotensin-system blockers are thought to increase the risk of acute kidney injury after surgery and hemorrhage. We found that losartan does not cause renal cortical hypoxia after hemorrhage in rats because of decreased renal vascular resistance, but we did not evaluate resuscitation. We aimed to study losartan’s effect on renal cortical and medullary oxygenation, as well as norepinephrine’s vasopressor effect in a model of resuscitated hemorrhage. After 7 days of losartan (60 mg·kg−1·day−1) or control treatment, male Wistar rats were hemorrhaged 20% of their blood volume and resuscitated with Ringerʼs acetate. Mean arterial pressure, renal blood flow, and kidney tissue oxygenation were measured at baseline and after resuscitation. Finally, the effect of norepinephrine on mean arterial pressure and renal blood flow was investigated. As expected, losartan lowered mean arterial pressure but not renal blood flow. Losartan did not affect renal oxygen consumption and oxygen tension. Mean arterial pressure and renal blood flow were lower after resuscitated hemorrhage. A smaller increase of renal vascular resistance in the losartan group translated to a smaller decrease in cortical oxygen tension, but no significant difference was seen in medullary oxygen tension, either between groups or after hemorrhage. The effect of norepinephrine on mean arterial pressure and renal blood flow was similar in control- and losartan-treated rats. Losartan does not decrease renal oxygenation after resuscitated hemorrhage because of a smaller increase in renal vascular resistance. Further, losartan does not decrease the efficiency of norepinephrine as a vasopressor, indicating that blood pressure may be managed effectively during losartan treatment.

Inhibition of ROMK blocks macula densa tubuloglomerular feedback yet causes renal vasoconstriction in anesthetized rats

The Na+-K+-2Cl− cotransporter (NKCC2) on the loop of Henle is the site of action of furosemide. Because outer medullary potassium channel (ROMK) inhibitors prevent reabsorption by NKCC2, we tested the hypothesis that ROMK inhibition with a novel selective ROMK inhibitor (compound C) blocks tubuloglomerular feedback (TGF) and reduces vascular resistance. Loop perfusion of either ROMK inhibitor or furosemide caused dose-dependent blunting of TGF, but the response to furosemide was 10-fold more sensitive (IC50 = 10−6 M for furosemide and IC50 = 10−5 M for compound C). During systemic infusion, both diuretics inhibited TGF, but ROMK inhibitor was 10-fold more sensitive (compound C: 63% inhibition; furosemide: 32% inhibition). Despite blockade of TGF, 1 h of constant systemic infusion of both diuretics reduced the glomerular filtration rate (GFR) and renal blood flow (RBF) by 40–60% and increased renal vascular resistance (RVR) by 100–200%. Neither diuretic altered blood pressure or hematocrit. Proximal tubule hydrostatic pressures (PPT) increased transiently with both diuretics (compound C: 56% increase; furosemide: 70% increase) but returned to baseline. ROMK inhibitor caused more natriuresis (3,400 vs. 1,600% increase) and calciuresis (1,200 vs. 800% increase) but less kaliuresis (33 vs. 167% increase) than furosemide. In conclusion, blockade of ROMK or Na+-K+-2Cl− transport inhibits TGF yet increases renal vascular resistance. The renal vasoconstriction was independent of volume depletion, blood pressure, TGF, or PPT.