The vascular resistance of the foetal and newly ventilated lung of the lamb

Cassin, S.; Dawes, G. S.; Mott, Joan C.; Roß, Bernhard; Strang, L. B.

doi:10.1113/jphysiol.1964.sp007361

Cited by 264 publications

(130 citation statements)

References 11 publications

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“…Coincident with this role there is an increase in both pulmonary and renal blood flow, although these occur at different rates. Measurements of pulmonary vascular resistance in both humans [8] and experimental animals [5] demonstrate age-related decreases. The present studies demonstrated a similar decrease in renal vascular resistance.…”

Section: Fetal and Neonatal Changes In Rbf And Pulmonary Blood Flowmentioning

confidence: 99%

Maturational Changes in Renal Blood Flow in Piglets

1970

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ExtractCardiac output, renal blood flow, and intrinsic renal vascular resistance were measured in piglets ranging in age from 6 h to 45 days. During this period of time the mean cardiac output increased from 0.9 to 6.5 liters/min/m . These data demonstrate that the large increase in renal blood flow in the pig during the first 6 weeks of life was due to both an increase in cardiac output as well as a decrease in renal vascular resistance. By 6 weeks of age, cardiac output was at adult levels. Since in the adult pig the kidney receives 20 % of the cardiac output, increases in renal blood flow beyond 6 weeks of age must result from further decreases in renal vascular resistance. SpeculationIn the human infant, cardiac index is comparable to values observed in the adult. It appears, therefore, that the entire increase in renal blood flow observed during year 1 of life is due to steadily decreasing renal vascular resistance. Since glomerular filtration rate is modified by the relative resistances in the glomerular afferent and efferent arterioles, the parallel increases in filtration rate during infancy may be related to the same mechanism.Introduction mates renal plasma flow by not more than 30-40%. Rates of flow reach mature levels (1,200 ml/min/1.73 Numerous studies have shown that renal blood flow m

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Section: Fetal and Neonatal Changes In Rbf And Pulmonary Blood Flowmentioning

confidence: 99%

Maturational Changes in Renal Blood Flow in Piglets

1970

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“…After birth, with initiation of ventilation by the lungs, and the subsequent increase in pulmonary and systemic arterial blood oxygen tensions, pulmonary vascular resistance decreases and pulmonary blood flow increases by 8-10-fold to match systemic blood flow (1)(2)(3)(4). This process is regulated by a complex and incompletely understood interplay between mechanical and metabolic factors (5).…”

Section: Introductionmentioning

confidence: 99%

“…The increase in alveolar or pulmonary and systemic arterial blood oxygen tensions decreases pulmonary vascular resistance either directly by dilating the small pulmonary arteries, or indirectly by stimulating the production of vasodilator substances such as nitric oxide (NO) 1 (8)(9)(10). Endothelial cells synthesize NO and l -citrulline from l -arginine by the action of the enzyme endothelial nitric oxide synthase (eNOS) (11,12).…”

Section: Introductionmentioning

confidence: 99%

Ventilation and oxygenation induce endothelial nitric oxide synthase gene expression in the lungs of fetal lambs.

Black¹,

Johengen²,

Dong³

et al. 1997

J. Clin. Invest.

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At birth, ventilation and oxygenation immediately decrease pulmonary vascular resistance (PVR) and increase pulmonary blood flow (PBF); more gradual changes occur over the next several hours. Nitric oxide, produced by endothelial nitric oxide synthase (eNOS), mediates these gradual changes. To determine how ventilation and oxygenation affect eNOS gene expression, 12 fetal lambs were ventilated for 8 h without changing fetal descending aortic blood gases or pH (rhythmic distension) or with 100% oxygen (O 2 ventilation). Vascular pressures and PBF were measured. Total RNA, protein, and tissue sections were prepared from lung tissue for RNase protection assays, Western blotting, and in situ hybridization. O 2 ventilation increased PBF and decreased PVR more than rhythmic distension ( P Ͻ 0.05). Rhythmic distension increased eNOS mRNA expression; O 2 ventilation increased eNOS mRNA expression more and increased eNOS protein expression ( P Ͻ 0.05). To define the mechanisms responsible for these changes, ovine fetal pulmonary arterial endothelial cells were exposed to 1, 21, or 95% O 2 or to shear stress. 95% O 2 increased eNOS mRNA and protein expression ( P Ͻ 0.05). Shear stress increased eNOS mRNA and protein expression ( P Ͻ 0.05). Increased oxygenation but more importantly increased PBF with increased shear stress induce eNOS gene expression and contribute to pulmonary vasodilation after birth. (

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“…Otra de las razones del aumento de la luz arteriolar pulmonar se debe a que el flujo sanguíneo a través de los pulmones al nacimiento es del 100%, en comparación a la circulación pulmonar fetal donde el pulmón úni-camente recibe menos del 20% del gasto ventricular derecho, siendo el resto derivado a través del conducto arterioso persistente (CAP) hacia la aorta descendente y la circulación placentaria (Cassin et al, 1964). Además, los vasos sanguíneos pulmonares se vuelven más reactivos al efecto vasodilatador del oxígeno a medida que el feto se va acercando al nacimiento, pues la baja presión parcial de oxígeno presente durante la vida fetal y la liberación de los vasoconstrictores endógenos endotelina-1 y tromboxano facilitan el mantenimiento de una alta resistencia vascular pulmonar (RVP) (Lakshminrusimha y Steinhorn, 1999).…”

Section: Resultados Y Discusiónunclassified

Evaluación Posnatal De Las Arteriolas Pulmonares en Crías De Alpaca

Manrique

Lira

Vásquez

et al. 2013

Rev. investig. vet. Perú

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RESUMENEn la etapa posnatal de mamíferos es de vital importancia la vasodilatación de las arteriolas pulmonares, pues de estas dependerá la cantidad de sangre que pase por los alveolos para ser oxigenada. El presente estudio tuvo por objetivo evaluar el diámetro, el grosor de la capa muscular y la relación capa muscular/diámetro arteriolar (CM/DA) para evaluar los cambios de la luz vascular en la etapa posnatal de crías de alpaca. Se utilizaron pulmones de 36 alpacas de 1 a 45 días de edad, distribuidos en nueve grupos etarios (un grupo por cada cinco días de edad). Los cortes histológicos de pulmón fueron coloreados con hematoxilina fosfotúngstica de Mallory. El diámetro arteriolar pulmonar mostró un incremento significativo (p<0.05) entre los grupos etarios 1 y 2 versus 7, 8 y 9. El grosor de la capa muscular no evidenció cambios significativos entre grupos, mientras que los valores de la relación CM/DA se incrementaron con la edad, habiendo diferencias estadísticas entre grupos etarios 1 y 2 versus 6, 7, 8 y 9 (p<0.05). Se concluye que la relación CM/DA disminuye y el lumen de las arteriolas pulmonares aumenta a medida que la edad de los animales se incrementa, debido al aumento del diámetro arteriolar pulmonar (p<0.05), mas no del grosor del músculo liso. Palabras clave: arteriolas pulmonares, posnatal, crías de alpaca ABSTRACTIn the postnatal phase in mammalians, the vasodilatation of the pulmonary arterioles is critical, since this will affect the amount of blood passing through the alveoli for oxygenation. The aim of the study was to evaluate the diameter, the thickness of the muscle layer and the relationship muscle layer/arteriolar diameter (CM/DA) as indication of changes in the vascular lumen in the postnatal period of baby alpacas. Lungs of 36 alpacas between 1 to 45 days of age were obtained according to nine age groups (one group each 5 days of age). The lung histological sections were stained with Mallory's phosphotungstic acid hematoxylin. The arteriolar diameter showed a significant increase

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The vascular resistance of the foetal and newly ventilated lung of the lamb

Cited by 264 publications

References 11 publications

Maturational Changes in Renal Blood Flow in Piglets

Maturational Changes in Renal Blood Flow in Piglets

Ventilation and oxygenation induce endothelial nitric oxide synthase gene expression in the lungs of fetal lambs.

Evaluación Posnatal De Las Arteriolas Pulmonares en Crías De Alpaca

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