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Renal Circulation (renal + circulation)
Selected AbstractsIntrauterine growth restriction reduces nephron number and renal excretory function in newborn piglets,ACTA PHYSIOLOGICA, Issue 2 2002R. Bauer ABSTRACT To examine the effects of intrauterine growth restriction on nephron number, renal circulation, and renal excretory functions in newborns, studies were conducted on 1-day-old anaesthetized piglets, divided into normal weight (n = 6) and intrauterine growth restricted (n = 6) piglets. Renal blood flow was measured by coloured microspheres, glomerular filtration rate was measured by inulin clearance, and osmotic clearance and fractional sodium excretion were calculated. In addition, an estimation of the nephron number was performed by counting representative glomerular numbers in microscopic sections. Newborn intrauterine growth restricted piglets exhibited a reduced glomerular filtration rate and osmotic clearance (P < 0.05), whereas renal blood flow and the filtration fraction as well as fractional sodium excretion were similar in normal weight and intrauterine growth restricted piglets. The nephron number was markedly reduced in intrauterine growth restricted piglets even if the nephron number was related to body weight (P < 0.01). There was a positive correlation between nephron number and glomerular filtration rate (r = 0.69, P < 0.05). Reduced glomerular filtration rate of newborn intrauterine growth restricted piglets is associated with a reduced nephron number. Thus, at birth, compensatory response of renal function due to nephron deficit does not exist in intrauterine growth restricted piglets. [source] Assessment of renal circulation in small for gestational age and appropriate for gestational age term newborns: A prospective studyJOURNAL OF CLINICAL ULTRASOUND, Issue 4 2008Hana Kolarovszka Abstract Purpose To compare selected parameters of renal circulation between small for gestational age (SGA) and appropriate for gestational age (AGA) newborns. Methods Fifty-two SGA and 100 AGA term newborns were examined. The size of the kidneys were measured, and renal blood flow in the central and intraparenchymal renal arteries were assessed via Doppler sonography. Peak systolic velocity (PSV), end diastolic velocity (EDV), mean blood flow velocity (V mean), resistance index (RI), and pulsatility index (PI) were determined and compared between the groups. Results No statistically significant differences in the velocity parameters were found between SGA and AGA infants in central renal arteries. Slightly higher RIs and PIs were seen in AGA newborns (RI, 0.76 ± 0.13 versus 0.78 ± 0.06 [p < 0.05]; PI, 1.65 ± 0.54 versus 1.84 ± 0.46 [p < 0.05]). There were statistically significant differences between the groups in all measured parameters in intraparenchymal arteries (RI, 0.57 ± 0.11 versus 0.63 ± 0.05 [p < 0.001]; PI, 0.89 ± 0.26 versus 1.09 ± 0.16 [p < 0.001]) except PSV (7.11 ± 1.55 versus 7.14 ± 0.81 cm/s [p > 0.05]). Conclusion Based on our findings, we suggest that renal circulation is not negatively influenced by intrauterine growth restriction in SGA neonates compared with AGA newborns. © 2007 Wiley Periodicals, Inc. J Clin Ultrasound, 2008 [source] Doppler velocimetry of maternal renal circulation in pregnancy-induced hypertensionJOURNAL OF CLINICAL ULTRASOUND, Issue 8 2001Hidehiko Miyake MD Abstract Purpose The purpose of this study was to evaluate whether the Doppler waveforms of the maternal main renal, segmental, and interlobar arteries are altered in women with pregnancy-induced hypertension (PIH) compared with healthy pregnant women. Methods Flow waveforms of the maternal main renal, segmental, and interlobar arteries were obtained from 42 healthy pregnant women between 24 and 41 weeks of gestation and 21 women with PIH between 28 and 40 weeks of gestation using pulsed Doppler sonography. We used spectral analysis to measure the peak systolic and end-diastolic velocities and the acceleration time. The presence or absence of the normal early systolic compliance peak-reflective-wave complex (ESP) was assessed in only the main renal artery. Results The acceleration times of the segmental and interlobar arteries were significantly prolonged in the PIH group compared with those in the healthy pregnant women. Of the 21 women with PIH, 3 showed loss of the ESP in the renal artery, but these changes were not significant. Conclusions Decreased systolic acceleration and the absence of ESP, the hemodynamic indicators for significant proximal stenosis, suggest that severe stenosis or continuous vasospasm in the proximal arteries, such as the main renal or segmental artery, may be implicated in the pathogenesis of PIH. © 2001 John Wiley & Sons, Inc. J Clin Ultrasound 29:449,455, 2001. [source] The angiotensin II receptor blocker candesartan improves survival and mesenteric perfusion in an acute porcine endotoxin modelACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 2 2004M. Laesser Background:, Blockade of the angiotensin II type 1 (AT1) receptor has been demonstrated to ameliorate splanchnic hypoperfusion in acute experimental circulatory failure. This study focused on hemodynamic changes and survival in pigs treated with AT1 blockade prior to or during acute endotoxinemia. Methods:,Escherichia coli lipopolysaccharide endotoxin was infused in anesthetized and mechanically ventilated pigs. Systemic, renal, mesenteric and jejunal mucosal perfusion as well as systemic oxygen and acid-base balance were monitored. The selective AT1 receptor blocker candesartan was administered prior to as well as during endotoxinemia. Control animals received the saline vehicle. Results:, Pre-treatment with candesartan resulted in higher survival rate (83%, 10 out of 12 animals) compared with 50% (6 of 12) in control animals and 27% (3 of 11) in animals treated during endotoxinemia. Pre-treatment with candesartan resulted in higher cardiac output, mixed venous oxygen saturation, arterial standard base-excess, portal venous blood flow during endotoxin infusion compared with controls and animals treated during endotoxinemia. No adverse effects were found on neither systemic nor renal circulation. Conclusion:, The favorable results of AT1 receptor blockade prior to endotoxinemia are lost when blockade is established during endotoxinemia demonstrating the importance of the renin-angiotensin system and its dynamic involvement in acute endotoxinemic shock. [source] Electrophysiological effects of endothelin-1 and their relationship to contraction in rat renal arterial smooth muscleBRITISH JOURNAL OF PHARMACOLOGY, Issue 4 2000Luisa C Betts The electophysiological effects of endothelin-1 (ET-1) and their relationship to contraction remain unclear in the renal circulation. Using endotheliumdenuded arteries from the main branch of the renal artery proximal to the kidney of the rat, we have examined its effects on tension and conducted parallel patch-clamp measurements using freshly isolated smooth muscle cells from this tissue. Pharmacological experiments revealed that ET-1 produced constriction of renal arteries dependent on the influx of extracellular Ca2+, mediated solely through ETA receptor stimulation. Current-clamp experiments revealed that renal arterial myocytes had a resting membrane potential of ,32 mV, with the majority of cells exhibiting spontaneous transient hyperpolarizations (STHPs). Application of ET-1 produced depolarization and in those cells exhibiting STHPs, either caused their inhibition or made them occur regularly. Under voltage-clamp conditions cells were observed to exhibit spontaneous transient outward currents (STOCs) inhibited by iberiotoxin. Application of voltage-ramps revealed an outward current activated at ,,30 mV, sensitive to both 4-AP and TEA. Taken together these results suggest that renal arterial myocytes possess both delayed rectifying K+ (KV) and Ca2+ -activated K+ (BKCa) channels. Under voltage-clamp, ET-1 attenuated the outward current and reduced the magnitude and incidence of STOCs: effects mediated solely as a consequence of ETA receptor stimulation. Thus, in conclusion, activation of ETA receptors by ET-1 causes inhibition of KV and BKCa channel activity, which could promote and/or maintain membrane depolarization. This effect is likely to favour L-type Ca2+ channel activity providing an influx pathway for extracellular Ca2+ essential for contraction. British Journal of Pharmacology (2000) 130, 787,796; doi:10.1038/sj.bjp.0703377 [source] | ||||||||||