Autoregulation of renal blood flow in the puppy

Pa, Jose; Slotkoff, LM; Montgomery, S B; Pl, Calcagno; Eisner, GM

doi:10.1152/ajplegacy.1975.229.4.983

Cited by 63 publications

(20 citation statements)

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“…As previously shown in newborn rabbits (4,(7)(8)(9)(10)(11)19), as well as lambs and puppies (33)(34)(35), acute normocapnic hypoxemia in the present study was associated with a significant drop in GFR, together with a concomitant decrease in RBF, MAP, and diuresis, and a significant increase in RVR. Administration of the specific A 1 antagonist DPCPX totally prevented the well-documented hypoxemia-induced fall in GFR and diuresis; both parameters were not modified from the control period to the experimental hypoxemia plus DPCPX periods, although MAP remained significantly decreased.…”

Section: Map Heart Rate (Hr) Hematocrit (Htc) Plasma Protein Levsupporting

confidence: 88%

Renal Effects of Adenosine A1-Receptor Blockade with 8-Cyclopentyl-1,3-Dipropylxanthine in Hypoxemic Newborn Rabbits

et al. 2003

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The key role of intrarenal adenosine in mediating the hypoxemic acute renal insufficiency in newborn rabbits has been well demonstrated using the nonspecific adenosine antagonist theophylline. The present study was designed to define the role of adenosine A 1 receptors during systemic hypoxemia by using the specific A 1 -receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX). Renal function parameters were assessed in 31 anesthetized and mechanically ventilated newborn rabbits. In normoxia, DPCPX infusion induced a significant increase in diuresis (ϩ44%) and GFR (ϩ19%), despite a significant decrease in renal blood flow (RBF) (Ϫ22%) and an increase in renal vascular resistance (RVR) (ϩ37%). In hypoxemic conditions, diuresis (Ϫ19%), GFR (Ϫ26%), and RBF (Ϫ35%) were decreased, whereas RVR increased (ϩ33%). DPCPX administration hindered the hypoxemia-induced decrease in GFR and diuresis. However, RBF was still significantly decreased (Ϫ27%), whereas RVR increased (ϩ22%). In all groups, the filtration fraction increased significantly. The overall results support the hypothesis that, in physiologic conditions, intrarenal adenosine plays a key role in regulating glomerular filtration in the neonatal period through preferential A 1 -mediated afferent vasoconstriction. During a hypoxemic stress, the A 1 -specific antagonist DPCPX only partially prevented the hypoxemiainduced changes, as illustrated by the elevated RVR and drop in RBF. These findings imply that the contribution of intrarenal adenosine to the acute adverse effects of hypoxemia might not be solely mediated via the A 1 receptor. Adenosine is ubiquitous in the kidney. Intrarenal adenosine vasoconstricts the preglomerular vessels via the A 1 receptors, while dilating the efferent arterioles via the A 2 receptors. It thus affects GFR as well as RBF and its distribution within the kidney. In addition to its vascular actions, intrarenal adenosine modulates renal mechanisms, including TGF, renin release, and the tubular handling of electrolytes and water. Intrarenal adenosine also appears to be an important hemodynamic mediator in some models of vasomotor nephropathy, such as those induced by intramuscular glycerol injection (1), contrast media (2), cisplatin (3), or hypoxemia (4).In animal models as in humans, hypoxemia can lead to functional renal insufficiency (5-7). In the newborn rabbit, acute normocapnic hypoxemia induces renal hypoperfusion with decreased GFR and RBF (4, 7-9). The underlying mechanism of this hypoxemia-induced vasomotor nephropathy still remains controversial. The chemoreceptor-mediated reflex and/or the activation of vasoactive factors such as angiotensin II (AII) (9), endothelin (10), nitric oxide (8), or bradykinin (11) have been suggested to play a role.We previously demonstrated that the administration of theophylline, a nonspecific antagonist to adenosine receptors, ameliorates the hypoxemia-induced renal hemodynamic changes seen in the newborn rabbit model (4). Moreover, in neonates with respiratory distress syndrome (12)

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Section: Map Heart Rate (Hr) Hematocrit (Htc) Plasma Protein Levsupporting

confidence: 88%

Renal Effects of Adenosine A1-Receptor Blockade with 8-Cyclopentyl-1,3-Dipropylxanthine in Hypoxemic Newborn Rabbits

et al. 2003

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“…The renin angiotensin system is highly activated at birth and during the maturation of renal hemodynamics (43-45). However, the contribution of angiotensin I1 as a vasoconstrictor in maintaining immature renal hemodynamics has not been demonstrated (14)(15)(16). The participation of vasodilators in the maturation of renal hemodynamics has received limited examination.…”

Section: 'mentioning

confidence: 99%

“…facilitates the matu---, rational increase in renal blood flow, remain largely unexplained. Previous investigations to explain the developmental phenomenon of renal hernodynamics have focused o n vasoconstrictor mechanisms such as an increased sympathoadrenergic response (8)(9)(10)(11)(12)(13), the highly activated renin angiotensin system (14)(15)(16), or activation of the prostanoid thromboxane ( 17). Prostaglandins, the only vasodilators examined, may participate in fetal renal hemodynamics (18) but have not been proven to regulate basal renal hemodynamics in the developing animal (1 5).…”

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confidence: 99%

Endothelium-Derived Nitric Oxide Modulates Renal Hemodynamics in the Developing Piglet

1993

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ABSTRACT. The developing mammal exhibits lower renal blood flow (RBF) and higher renal vascular resistance (RVR) than its adult counterpart. The maturational pattern of renal hemodynamics involves the synchronous increase in RBF and decrease in RVR with age. In spite of considerable investigation, the mechanisms involved in the regulation of renal hemodynamics in the developing animal remain largely unexplained. Specifically, the role of the vasodilator endotheliumderived nitric oxide (EDNO) in the regulation of developing renal hemodynamics is not known. These experiments examined the intrarenal effect on the renal hemodynamics of the developing piglet and adult pig of the EDNO competitive inhibitor N-nitro-Larginine methylester (L-NAME) at three doses (50,5, and 3 pg/kg/min). During basal conditions, the developing piglet exhibited lower RBF and higher RVR than the adult pig. All doses of intrarenal L-NAME produced significant decreases in RBF and increases in RVR in both groups. The 3-pg/kg/min L-NAME dose did not change mean arterial pressure. The developing piglet exhibited significantly greater changes at all doses. After the 50-pg/kg/min infusion, piglet RBF decreased 45% and adult pig RBF decreased 29%; piglet RVR increased 128% and adult pig RVR increased 51%. After a 5-pg/kg/min infusion, RBF

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“…Two blood samples were obtained from each infant, one at a mean 23 h (range [19][20][21][22][23][24][25][26][27] and the other at a mean 47 h (range 43-53) after birth. These samples were collected to coincide as closely as possible to the midpoint of each 24-h urine collection.…”

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confidence: 99%

The Effect of Assisted Ventilation on Creatinine Clearance and Hormonal Control of Electrolyte Balance in Very Low Birth Weight Infants

et al. 1986

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ABSTRACT. Because renal function and electrolyte balance are commonly altered in premature infants, particularly those requiring ventilatory support, we studied the influence of assisted ventilation on renal electrolyte and water excretion in infants with birth weights less than 1501 g during the 2 days after birth. Twenty-two infants receiving assisted ventilation, either as intermittent mandatory ventilation or nasal continuous positive airway pressure, were compared with 21 spontaneously ventilating infants of similar birthweight and gestational age. Mean (and SEM) creatinine clearance was lower ( p < 0.05) in the assisted ventilation group on day 1 (2.9 f 0.4 versus 4.1 f 0.4 ml/min/1.73 m2) and on day 2 (4.1 2 1.0 versus 6.8 + 0.8 ml/min/1.73 mZ, p = 0.05), and there was a correlation between creatinine clearance and mean blood pressure in both groups. Mean urine vasopressin was higher in the assisted ventilation group on the first day (360 f 86 versus 123 ? 30 pg/mg creatinine; p < 0.02) and correlated with higher urine osmolality. There were no differences in urine volume, in osmolar or free water clearances, or in the intake and urine excretion of sodium, potassium, and chloride. Plasma renin activity, urine aldosterone, and urine prostaglandin E2 were similar in both groups on both days. Neither the mode of assisted ventilation nor the cause of respiratory failure appeared to affect these results. (Pediatr Res 20: 447-452, 1986) Abbreviations PEEP. ~ositive end-ex~ired Dressure , -

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Autoregulation of renal blood flow in the puppy

Cited by 63 publications

References 0 publications

Renal Effects of Adenosine A1-Receptor Blockade with 8-Cyclopentyl-1,3-Dipropylxanthine in Hypoxemic Newborn Rabbits

Renal Effects of Adenosine A1-Receptor Blockade with 8-Cyclopentyl-1,3-Dipropylxanthine in Hypoxemic Newborn Rabbits

Endothelium-Derived Nitric Oxide Modulates Renal Hemodynamics in the Developing Piglet

The Effect of Assisted Ventilation on Creatinine Clearance and Hormonal Control of Electrolyte Balance in Very Low Birth Weight Infants

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