Cardiovascular and Renal Effects of Isoproterenol Infusions in Young Swine

Buckley, N. M.; Brazeau, Paul; Charney, Alan N.; Cabili, S; Feldman, George M.; Garvey, M. B.; Frasier, I. D.

doi:10.1159/000241779

Cited by 7 publications

(3 citation statements)

References 23 publications

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“…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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confidence: 99%

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

1993

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“…Little is known about the ontogeny of sympathoadrenal stimulated renal vasodilation. Buckley et al (6,7) have examined the postnatal development of renal vasodilatory mechanisms in anesthetized piglets (6, 7). Their studies have shown that the Padrenergic vasodilatory mechanism in the renal vascular bed of swine is absent at birth and appears postnatally at 2 wk.…”

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confidence: 99%

Ontogeny of Renal β-Adrenoceptor-Mediated Vasodilation in Sheep: Comparison between Endogenous Catecholamines

et al. 1987

Pediatr Res

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ABSTRACT. The renal hemodynamic response to renal arterial infusions of norepinephrine was compared to epinephrine infusions during renal a-adrenoceptor blockade in chronically instrumented and unanesthetized fetal (127-141 days gestation; term 145 days), newborn (6-10 days old), and nonpregnant adult sheep. Infusions of either catecholamines produced renal vasodilation which was of greater magnitude in fetal compared to newborn and adult sheep. Maximal increases in renal blood flow velocity during norepinephrine infusion were 64 f 5% in fetal, 23 f 4% in newborn, and 24 f 7% in adult sheep ( p < 0.001). Extremely high catecholamine levels are observed during fetal stress (1) and during birth (2,3), with the predominant circulating catecholamine being norepinephrine. In contrast, the sympathoadrenal response to stress in adults is associated with significantly lower plasma catecholamine values where epinephrine is the major circulating catecholamine (4). Because the sympathoadrenal system plays an important role in modulating renal hemodynamics ( 3 , knowledge about differences in sympathoadrenal activity during development and its functional role in determining RBF is of interest in perinatal medicine. Little is known about the ontogeny of sympathoadrenal stimulated renal vasodilation. Buckley et al. (6,7) have examined the postnatal development of renal vasodilatory mechanisms in anesthetized piglets (6, 7). Their studies have shown that the Padrenergic vasodilatory mechanism in the renal vascular bed of swine is absent at birth and appears postnatally at 2 wk. However, in chronically instrumented sheep, we have demonstrated during a-adrenoceptor blockade, enhanced renal P-adrenoceptor mediated vasodilator response to renal nerve stimulation (8) and to intrarenal infusions of epinephrine (unpublished observations) in fetal compared to newborn and adult sheep. In contrast, these results differ from dopamine-mediated vasodilator responses which are of considerably smaller magnitude in fetal, newborn, and adult sheep (9).Since levels of plasma catecholamines and of norepinephrine, the predominant circulating catecholamine found during stress, are age dependent, and because norepinephrine and epinephrine differ in their ability to stimulate the vascular P-adrenergic receptor (lo), the present protocol was designed to compare the renal hemodynamic response to renal arterial norepinephrine and epinephrine infusions during renal a-adrenoceptor blockade in chronically instrumented fetal, newborn, and adult sheep. METHODSAnimal preparation and surgical procedures. Fetuses of seven pregnant sheep of Dorset and Suffolk mixed breeding were studied between 127 and 141 days gestation (term was 145 days). Gestational ages were based on the induced ovulation technique as previously described (I 1).Ewes were fasted for 48 h prior to surgery. General anesthesia of the ewe and fetal surgery were performed as previously described (1 1). Briefly, when the ewe was receiving a mixture of 1% halothane. 33% oxvgen. and 66% nitrous oxi...

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“…The ontogeny of adrenergic receptors is still ill-defined in newborn mammals. In piglets studied at birth and subsequently at different postnatal ages [3,4], a vasoconstrictor tonus mediated by a-adrenergic innervation was present since birth. However, the response to nerve electric stimulation intensified with postnatal age and animals of less than 4 days only responded to high frequency stimulation.…”

Section: Discussionmentioning

confidence: 99%

Renal Effects of Tolazoline in Newborn and Adult Rabbits

Duarte-Silva¹,

S²,

Guignard³

1987

Dev Pharmacol Ther

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The effect of tolazoline on renal function was studied in normoxemic newborn and adult anesthetized rabbits. Adult animals responded to 1 mg/kg + 1 mg/kg/h of tolazoline with a marked increase in systemic blood pressure and renal vascular resistance along with a decrease in urine flow rate, glomerular filtration rate and renal blood flow. Blood pressure also increased in newborn rabbits given a similar dose of tolazoline, but the same renal parameters remained remarkably stable. The renal effect of tolazoline in adult animals probably corresponds to a partial a-agonist action of tolazoline. It is suggested that a relative adrenergic renal immaturity present in the newborn rabbit protects him from the deleterious effect of tolazoline.

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Cardiovascular and Renal Effects of Isoproterenol Infusions in Young Swine

Cited by 7 publications

References 23 publications

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

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

Ontogeny of Renal β-Adrenoceptor-Mediated Vasodilation in Sheep: Comparison between Endogenous Catecholamines

Renal Effects of Tolazoline in Newborn and Adult Rabbits

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