Acute Pulmonary Artery Hypertension Produced by Distention of the Main Pulmonary Artery in the Conscious Dog

Laks, Michael M.; Juratsch, Craig E.; Garner, Daniel; Beazell, James; Criley, J. Michael

doi:10.1378/chest.68.6.807

Cited by 36 publications

(16 citation statements)

References 23 publications

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“…Previous attempts to assess the role of pulmonary arterial baroreceptors have not satisfied the criteria set out for this study. For example, distension of balloons in and around the pulmonary bifurcation (Lewin et al 1961;Osorio & Russek, 1962;Laks et al 1975;Crisp et al 1988) do not apply a stimulus that is possible to relate to physiological events. There have been other studies of responses to changes in extrapulmonary pulmonary arterial pressures using blood perfusion of the isolated regions (Lewin et al 1961;Coleridge & Kidd, 1963;Ledsome & Kan, 1977).…”

Section: Discussionmentioning

confidence: 99%

“…However, although histological and electrophysiological evidence for the existence of functional baroreceptors within this region is convincing, the reflex cardiovascular responses to physiological stimulation of these receptors is less clear. Due to the complexity of applying discrete stimuli to the pulmonary artery and bifurcation, some investigators have distended this region by inflation of a balloon and this has resulted in variable responses of blood pressure and heart rate (Lewin et al 1961;Osorio & Russek, 1962;Laks et al 1975;Crisp et al 1988). It is difficult, however, to relate the responses to balloon distension with those to more normal physiological stimuli.…”

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confidence: 99%

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Reflex responses from the main pulmonary artery and bifurcation in anaesthetised dogs

et al. 2000

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

Reflex responses from the main pulmonary artery and bifurcation in anaesthetised dogs

et al. 2000

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“…Stretch of the main pulmonary artery in vivo by means of a nonocclusive balloon has been previously reported to increase pulmonary vascular resistance downstream in dogs, sheep, and human infants (15)(16)(17)(18)21). These results have been refuted on the basis that the increase in pulmonary vascular resistance was caused by the balloon obstruction of one of the main pulmonary artery branches (19,20).…”

Section: Discussionmentioning

confidence: 99%

“…Juratsch et al have shown that nonocclusive distension of the main pulmonary artery results in a significant increase in pulmonary vascular resistance in the dog (15)(16)(17) and sheep (18). Compared with the young and adult sheep, the increase in pulmonary vascular resistance was greatest in newborn sheep (18).…”

Section: Abbreviationsmentioning

confidence: 99%

Myogenic Response in Large Pulmonary Arteries and Its Ontogenesis

Belik

1994

Pediatr Res

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To evaluate the myogenic response and its ontogeny in large pulmonary arteries, we studied 45 newborn and 30 adult guinea pigs. Compared with the those of the adult, the newborn arterial vessels possessed a significantly @ < 0.01) smaller diameter (1153 ~t-34 versus 1656 5 65 km), static compliance (2.2 * 0.3 versus 4.6 * 0.7 pm/mN), and active stress (3.4 + 0.4 versus 5.8 ~t-0.7 mN/mm2). Stretchinduced contraction was obtained by quick stretch of the vessel segments to 120, 140, 160, 180, or 200% of their optimal length, and the myogenic response was measured as the change in force after muscle relaxation with papaverine. A myogenic response was observed in 94% of the newborn and 93% of adult vessel segments, and significant age differences in the response were present. The magnitude of the active force generated for any stretch over 120% was significantly greater in the newborn (p < 0.01), and as a percentage of K+ (127 mM) stimulation, a 2-fold Vessels respond to an increase in intraluminal pressure with vasoconstriction. This phenomenon, called the myogenic response or stretch-induced contraction, was originally described by Bayliss in 1902 (1). Previous data on in vitro vessel segments and in vivo organ perfusion studies of several animal species have confirmed its existence in a variety of systemic vessels (2-7). The phenomenon is most prevalent in small resistance units, and this has led to the current belief that the myogenic response plays an important role in organ autoregulation of blood flow after arterial pressure changes (2).Limited data are available on the myogenic response of lung vessels. In pulmonary allografts in the hamster, Davis et al. (8) were unable to observe any changes in arteriolar diameter after alterations in transmural pressure, whereas vasoconstriction was observed in systemic cheek pouch arterioles under similar conditions. T o the best of our knowledge, the only other study of the myogenic response in pulmonary vessels was reported by

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“…As the mechanism of action of prazosin involves competitive inhibition of a,-adrenergic receptors (5, 19), it appears that this type of receptor is not a major contributor to the elevated pulmonary arterial tone of lambs in the presence of a large left to right ventricular level shunt. It is possible that distension of the pulmonary arterial tree by the increased flow from the left to right shunt results in elevation of the pulmonary arteriolar vascular resistance in a manner described previously for ballooninduced distension of the pulmonary artery (16). This reflex has been shown to be unaffected by a-adrenergic antagonists (1 5).…”

Section: Discussionmentioning

confidence: 89%

Vasodilators and Ventricular Septal Defect: Comparison of Prazosin, Minoxidil, and Hydralazine in a Chronic Lamb Model

1984

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SummaryThe volume overloading of the left ventricle which results from left to right (L-R) shunting through a ventricular septal defect (VSD) may be reduced by pharmacologic agents which lower systemic vascular resistance (R,) in excess of pulmonary arteriolar vascular resistance (R,). To study agents capable of decreasing the L-R shunt through systemic vasodilatation, we created a chronic lamb model with VSD and administered three vasodilators, prazosin (0.05 mg/kg), hydralazine (0.75 mg/kg), and minoxidil (0.25 mg/kg). Prazosin increased the R, while lowering R,, resulting in an increase in R,/R by 43% ( p Q 0.005). Prazosin decreased the pulmonary flow (Q,) slightly, decreased L-R shunt by 16%, reduced the pulmonary to systemic flow ratio Received July 25, 1983; accepted February 7, 1984 (QP/QS) b c 2 % ( p Q 0.005), and lowered the left atrial mean pressure (LA) by 16% ( p s 0.005) with no effect on heart rate.Hydralazine lowered the R, and R, equally and thus did not change the R,/R, or the v o l s e of L-R shunt (7.6 versus 8.1 liters/min/m2). No change in LA was seen with hydralazine but heart rate increased from 162 to 200/min (p 4 0.01). Minoxidil did not change the L-R shunt (6.9 versus 6.8 liters/min/m2) and, in general, produced effects intermediate between prazosin and hydralazine. The data support a selective systemic vasodilation with prazosin, a property not shared by either minoxidil or hydralazine, which results in a reduction of shunting and left ventricular volume overloading in lambs with VSD. Furthermore, since prazosin did not decrease the pulmonary resistance, the data indicate that the elevation in pulmonary resistance in lambs with VSD is not mediated by the a,-adrenergic receptor. Abbreviations VSD, ventricular septal defect R, , pulmonary arteriolar vascular resistance

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Acute Pulmonary Artery Hypertension Produced by Distention of the Main Pulmonary Artery in the Conscious Dog

Cited by 36 publications

References 23 publications

Reflex responses from the main pulmonary artery and bifurcation in anaesthetised dogs

Reflex responses from the main pulmonary artery and bifurcation in anaesthetised dogs

Myogenic Response in Large Pulmonary Arteries and Its Ontogenesis

Vasodilators and Ventricular Septal Defect: Comparison of Prazosin, Minoxidil, and Hydralazine in a Chronic Lamb Model

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