Blood Pressure and Flow in the Ascending Aorta of Conscious Dogs

Noble, Mark I. M.; Gabe, I. T.; Trenchard, D; Guz, A.

doi:10.1093/cvr/1.1.9

Cited by 76 publications

(22 citation statements)

References 17 publications

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“…39 Our result, however, demonstrated no significant correlation and is in agreement with other previous studies. [40][41][42] There was also a contradictory study showing reduced aortic stiffness and increased distensibility during incremental pacing. 43 Therefore, in order to clarify the relationship between arterial distensibility and heart rate, and its pathophysiology, further specific studies are necessary.…”

Section: Discussionmentioning

confidence: 99%

Relationship between blood pressure parameters and pulse wave velocity in normotensive and hypertensive subjects: invasive study

et al. 2006

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Blood pressure (BP) is one of the most important contributing factors to pulse wave velocity (PWV), a classic measure of arterial stiffness. Although there have been many non-invasive studies to show the relation between arterial stiffness and BP, the results are controversial. The aim of this study is to evaluate the role of BP as an influencing factor on PWV using invasive method. We observed 174 normotensive and untreated hypertensive subjects using coronary angiography. Arterial stiffness was assessed through aorto-femoral PWV by foot-to-foot velocity method using fluid-filled system. And BP was measured by pressure wave at the right common femoral artery. From univariate analysis, age, diabetes mellitus (DM), hypertension, waist, waist-to-hip ratio, total cholesterol-tohigh-density lipoprotein cholesterol ratio, systolic BP (SBP), pulse pressure (PP) and mean arterial pressure (MAP) showed significant association with PWV. To avoid multiple colinearity among SBP, PP and MAP, we performed multiple regression analysis predicting PWV thrice. Age, DM and each BP were significantly and consistently correlated to PWV. In the first and third modules, compared to age, SBP and MAP were less strong predictors, respectively. However, PP was the stronger predictor than age and DM in the second module. Lastly, we simultaneously forced MAP and PP with other variables in the fourth multivariate analysis. Age, DM and PP remained significantly correlated with PWV, but the significance of MAP was lost. This is the first invasive study to suggest that PP has the strongest correlation with PWV among a variety of BP parameters.

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Section: Discussionmentioning

confidence: 99%

Relationship between blood pressure parameters and pulse wave velocity in normotensive and hypertensive subjects: invasive study

et al. 2006

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“…On intravenous administration there is an increase in heart rate, cardiac output and rate of left ventricular ejection; stroke volume may be increased or unchanged; in man diastolic arterial pressure is reduced although mean arterial pressure is unchanged, but in dogs both pressures are reduced (Krasnow, et a!., 1964;Harris. Schoenfeld, Brooks & Weissler, 1966;Shanks, 1966;Noble, Gabe, Trenchard & Guz, 1967). The inhalation of isoprenaline in man increases heart rate and forearm flow (Chamberlain, 1967;Cohen, Keates & Young, 1967) and presumably will produce the other changes in the circulation.…”

Section: Discussionmentioning

confidence: 99%

The cardio‐toxicity of isoprenaline during hypoxia

Collins¹,

McDevitt²,

Shanks³

et al. 1969

British J Pharmacology

104

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The effects of the intravenous injection of isoprenaline on heart rate and arterial pressure has been studied in dogs artificially respired with room air or with 12% oxygen—88% nitrogen. In dogs breathing room air, isoprenaline in doses from 0.02 to 500 μg/kg increased heart rate and reduced arterial pressure. Ventricular fibrillation was produced in one out of three dogs given 250 μg/kg. This was the only dog breathing room air which was killed by isoprenaline. In dogs breathing room air the repeated intravenous injection at 5‐min intervals of 2.5 μg/kg increased heart rate and reduced arterial pressure. No ill effects were produced by six doses. In dogs respired with 12% oxygen—88% nitrogen the Pao2 was reduced from 84 to 38 mm Hg with no changes in Paco2. In these dogs death was produced by doses of isoprenaline which in dogs breathing room air produced normal responses. The fatal dose of isoprenaline (10–50 μg/kg) reduced heart rate and arterial and pulse pressures; sinus rhythm persisted until arterial pressure was less than 50 mm Hg. Ventricular fibrillation did not occur; death occurred from cardiac asystole. Death was produced in a similar way in dogs with hypoxaemia by giving four or five doses of isoprenaline (2.5 μg/kg) at 5‐min intervals or by two doses of 25 μg/kg. The final reduction in arterial pressure during a fatal response resulted from a reduction in cardiac contractility. These lethal effects of isoprenaline could be prevented by pretreatment with propranolol.

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“…2). This higher aortic pressure, which results presumably from higher acceleration 12 ' 1S and greater distention in early systole, may be stored and discharged by the elastic wall of the aorta to constitute a higher force opposing ejection in late systole. Since the blood has high velocity at the beginning of deceleration, and would therefore tend to continue under its own momentum (mass X velocity), the higher opposing force at this time would reduce this momentum more rapidly; its effectiveness would depend on the weak, or even passive, nature of late systolic shortening.…”

Section: Discussionmentioning

confidence: 99%

“…Wilcken et al 14 showed that, when the abdominal aorta was opened to the atmosphere between two consecutive beats, the stroke volume of the second beat was increased greatly, while maximum acceleration was hardly affected ( fig. 3 of Wilcken et al 12 ). Since the only change which had taken place was a fall in peripheral impedance, the extra blood must have left the ventricle in late systole because of greatly reduced opposition to the momentum of the blood.…”

Section: Circulation Roelrch Vol XIX July 1966mentioning

confidence: 93%

Left Ventricular Ejection in Conscious Dogs:

Noble

Trenchard

Guz

1966

Circulation Research

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Some factors affecting stroke volume were investigated in conscious dogs in which left ventricular outflow was measured with an electromagnetic flowmeter. Stimulation of the heart at constant heart rate, by intracoronary injections of calcium gluconate and isopropylnorepinephrine, or postectopic potentiation failed to produce any increase in stroke volume. By contrast, alterations of posture at constant heart rate with the presumed associated changes in end diastolic dimensions, produced large changes in stroke volume. This resulted from a change in late systolic flow. ADDITIONAL KEY WORDSstroke volume myocardial contractility paired pulse potentiation calcium gluconate isopropylnorepinephrine posture momentum of blood unanesthetized dogs• It is well known that changes in end diastolic volume and heart rate affect stroke volume. 1 " 3 It is also thought that increases of myocardial contractility augment stroke volume. 4 In the present investigation it was intended originally to utilise this augmentation in order to study the effects of increased cardiac output. It was found, however, that stroke volume could not be increased by any of the methods of myocardial stimulation attempted. This surprising result has prompted the present study of the determinants of stroke volume.Methods Fifteen dogs, with implanted flowmeter transducers, right atrial electrodes and intracoronary and intracardiac catheters were used; their preparation and the evidence of their state of health were described in the previous paper.8 Intracoronary injections of isopropylnoradrenaline (0.5 to 1.0 /ig) and calcium gluconate (7.5 to 10 mg) were given in doses which had no effect when injected into the aorta or intravenously. Supported by Grant HE-06851-04 from the U. S. Public Health Service.Abraham Guz received a personal grant from the British Heart Foundation.Accepted for publication February 7, 1966. Paired pulse stimulation was done through the implanted right atrial electrode; the normal atrioventricular conduction and contraction sequences were thus preserved. Pairs of impulses 100 to 300 msec apart were delivered to the right atrium so that the second pulse of each pair produced an atrial ectopic stimulation which activated the ventricle but came too soon after the first impulse to produce ejection. However, it still potentiated the beat produced by the first impulse of the next pair. 6 The effects of paired pulse stimulation were compared with those of single pulse atrial stimulation at the same heart rate.The effects of alterations of posture were studied by passively lifting the standing dog by the front legs or passively lowering the sitting dog by the front legs; the details of these postural changes have been described and illustrated. 5 The instrumentation used for the measurement of blood flow and pressures and the methods of calibration have also been fully described.

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Blood Pressure and Flow in the Ascending Aorta of Conscious Dogs

Cited by 76 publications

References 17 publications

Relationship between blood pressure parameters and pulse wave velocity in normotensive and hypertensive subjects: invasive study

Relationship between blood pressure parameters and pulse wave velocity in normotensive and hypertensive subjects: invasive study

The cardio‐toxicity of isoprenaline during hypoxia

Left Ventricular Ejection in Conscious Dogs:

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