Responses of aortic smooth muscle studied in intact dogs

Pieper, H.P.; Paul, L. T.

doi:10.1152/ajplegacy.1969.217.1.154

Cited by 32 publications

(16 citation statements)

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“…The major fraction of prior work on aortic elastic properties has been performed on excised vessels or vessel strips (Bergel, 1972;McDonald, 1974;Roach and Burton, 1959;Learoyd and Taylor, 1966;Roach, 1970;Berry et al, 1975;Cox et al, 1976;Alexander, 1954;Vatner and Braunwald, 1975), or in anesthetized animals (Bergel, 1972;McDonald, 1974;Pieper and Paul, 1969;Aars, 1971;Nicolosi and Pieper, 1971;Pagani et al, 1975;Patel and Vaishnav, 1972;Gow, 1972;Gow and Taylor, 1968;Cox, 1975;Gow, 1970;Alexander, 1954;Wiggers and Wegria, 1938;Peterson et al, 1960;Patel et al, 1961;Remington, 1962;Gerova et al, 1973). In 1972, Gow noted that "new techniques are required to produce a continuous monitor of vascular dimensions in conscious animals, thus allowing the precise measurement of the normal physiological variations in vascular calibre and viscoelastic properties."…”

Section: Discussionmentioning

confidence: 99%

“…The instantaneous relationship between aortic pressure and diameter was analyzed on a beat-by-beat basis, using a storage oscilloscope, as shown in Figure 3. With this technique it became apparent that, at control, as well as with rising pressure and diameter, the hysteresis of the pressure-diameter loop (pressure leading diameter) was minimal (Pieper and Paul, 1969;Pagani et al, 1975;Gow, 1970), whereas it increased with the hypotension and tachycardia that follow nitroglycerin. In the newborn, this hysteresis tended to be more marked (Fig.…”

Section: Effects Of Nitroglycerin and Angiotensin Bolusesmentioning

confidence: 99%

“…The mechanical properties of the aortic wall play a major role in regulating the interrelationship between aortic pressure, flow, and dimensions (Bergel, 1972;McDonald, 1974) and, hence, in determining the coupling between the left ventricle and the systemic circulation (Bergel, 1972;McDonald, 1974;Urschel et al, 1968;Taylor, 1964). Moreover, anesthesia and acute manipulation of the vessel to be studied may, by themselves, affect elastic stiffness and smooth muscle tone (Pieper and Paul, 1969;Aars, 1971;Nicolosi and Pieper, 1971;Altura and Altura, 1975).…”

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confidence: 99%

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Effects of age on aortic pressure-diameter and elastic stiffness-stress relationships in unanesthetized sheep.

Pagani¹,

Mirsky²,

Baig³

et al. 1979

Circulation Research

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SUMMARY The effects of aging and smooth muscle activation on the elastic stiffness of the aortic wall were assessed in nine unanesthetized adult sheep, seven newborn (<1 week) lambs, and five near term fetal lambs in utero, previously instrumented with pressure gauges and ultrasonic dimension crystals for measurements of internal pressure and external diameter in the proximal third of the descending thoracic aorta. Angiotensin and nitroglycerin were administered as intravenous (iv) boluses to increase or decrease pressure and diameter. The midwall stress (u)-radius data were fitted to an exponential curve (r > 0.95) for each animal. The curves obtained in this way were similar to those obtained by inflating and deflating an implanted hydraulic occluder. Incremental elastic modulus (Einc) was derived as a linear function of stress. Compared at similar a levels, Eiac was significantly (P < 0.05) lower in the adults than in either the newborn or the fetuses. For example, at a -3.30 x 10* dynes/cm 1 , Ei«, was 1.41 ± 0.10 x 10* dynes/cm 1 in the adults, compared with 2.41 ± 0.35 in the lambs and 2.31 ± 0.15 in the fetuses. However, when Eim was calculated at the higher stress value corresponding to baseline mean arterial pressure, {a -6.90 ± 0.59 x 10* dynes/cm* in the adult, 3.36 ± 0.27 in the newborn, 3.62 ± 0.56 in the fetus), E&*. was only slightly higher in the adults (3.67 ± 0.50 x 10' dynes/ cm 1 ) than in the newborns (2.42 ± 0.38) or the fetuses (2.58 ± 0.58). a-Adrenergic activation of aortic smooth muscle, induced by methoxamine infusion, shifted pressure-diameter and stress-radius relationships toward higher pressure or stress for any given radius in the adult, whereas no alteration was observed in unanesthetized fetal or newborn lambs or in adults anesthetized with pentobarbitaL Thus the aortic elastic modulus at any given wall stress is lower in the unanesthetized adult sheep than in the newborn or the fetus. However, the responsiveness of aortic smooth muscle to a-adrenergic stimulation increases with age. Ore Res 44: 1979

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Section: Discussionmentioning

confidence: 99%

Section: Effects Of Nitroglycerin and Angiotensin Bolusesmentioning

confidence: 99%

mentioning

confidence: 99%

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Effects of age on aortic pressure-diameter and elastic stiffness-stress relationships in unanesthetized sheep.

Pagani¹,

Mirsky²,

Baig³

et al. 1979

Circulation Research

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“…infusion of noradrenaline. Pieper and Paul (1969) studied the aortic response to removal of up to 20 % of estimated blood volume in 40 dogs. Diastolic diameter of descending aorta was usually reduced at comparable pressures during hypovolemia, presumably due to increased muscular activity of the aorta.…”

Section: Discussionmentioning

confidence: 99%

“…It therefore became important to avoid thoracotomy and exposure of the vessel. Pieper and Paul ( 1969) studied the pressure/diameter relationship of thoracic aorta in dogs by means of a catheter-tip strain gauge inserted through the femoral artery. They found that, at comparable pressures, hemorrhage caused a reduction 134 H. AARS in aortic diameter, but minor or no changes in the modulus of elasticity or the calculated pulse-wave velocity.…”

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Diameter and Elasticity of the Ascending Aorta during Infusion of Noradrenaline

Aars

1971

Acta Physiologica Scandinavica

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h R S , H. Diameter and elasticity of the ascending aorta during infusion of noradrenaline. Acta physiol. scand. 1971. 83. 133-138.The effect of smooth muscle contraction on diameter and elasticity of the ascending aorta was examined in 18 anesthetized rabbits. Aortic diameter was measured with ultrasonic technique inside the intact thorax, and blood pressure was recorded from a catheter in the right common carotid artery. Control observations were obtained at various blood pressure levels by producing stepwise changes of the blood volume. At diastolic pressures from 40-90 mm Hg, i.v. infusion of noradrenaline (4-6 pglkg .min) caused a 6.6 70 average reduction in diastolic aortic diameter. Noradrenaline at low pressures increased the aortic pressure-strain elastic modulus (E,) and theoretical pulse-wave velocity (PWV) by 30-67 %. Control values of E, and PWV were slightly higher for rabbits than those usually found in dogs. It is concluded that at comparable pressures, contraction of aortic smooth muscle tissue, induced by infusion of noradrenaline, produces a small but significant constriction of the ascending aorta, and, at low pressures only, increases dynamic stiffness of the vessel.

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Hemodynamic correlates of arterial compliance

Ferguson

Randall

1986

Cathet. Cardiovasc. Diagn.

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There is at present no good understanding of the exact clinical correlates of arterial compliance. The purpose of this study was to establish which hemodynamic variables are most strongly associated with compliance. Hemodynamic measurements were performed on 41 patients undergoing diagnostic cardiac catheterization. Cardiac outputs were determined by thermodilution, and pressures were measured in the ascending aorta with a catheter-tip manometer. Compliance was calculated from a mono-exponential fit of diastolic decay pressures. Pulse pressure(PP), stroke volume(SV), age, systolic blood pressure(SBP), and cardiac output(CO) were significantly related to compliance. The quotient SV/PP was a good estimate of compliance, as was a first-order function of both SV and PP. There appear to be specific clinical correlates of arterial compliance, as well as ways to estimate arterial compliance on the basis of conventional hemodynamic measurements when direct calculations are not possible.

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Responses of aortic smooth muscle studied in intact dogs

Cited by 32 publications

References 0 publications

Effects of age on aortic pressure-diameter and elastic stiffness-stress relationships in unanesthetized sheep.

Effects of age on aortic pressure-diameter and elastic stiffness-stress relationships in unanesthetized sheep.

Diameter and Elasticity of the Ascending Aorta during Infusion of Noradrenaline

Hemodynamic correlates of arterial compliance

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