The Effects of Exercise on Central Blood Volume in Man

Braunwald, Eugene; Kelly, Eugene R.; Bullock, Frederick A.

doi:10.1172/jci104052

Cited by 46 publications

(11 citation statements)

References 22 publications

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“…It is well established from measurements of carbon monoxide uptake by the lung (6), and changes in mean transit time of tracers through the lung (4,5) that exercise causes a two-to threefold increase in lung blood volume in animals and man. The relative contribution of capillary dilation and capillary recruitment to this increased pulmonary blood volume is debated (41).…”

Section: Discussionmentioning

confidence: 99%

“…Vigorous exercise causes a marked increase in cardiac output, a minimal increase in pulmonary arterial pressure (1)(2)(3), and a decrease in calculated pulmonary vascular resistance. The reduction in resistance to blood flow through the lung during exercise results from pulmonary vascular recruitment and or dilatation and an increase in perfused microvascular surface area (2)(3)(4)(5)(6). This, in turn, should cause an increased exchange of fluid across the pulmonary capillaries with a concomitant increase in lymph flow from the lungs.…”

Section: Introductionmentioning

confidence: 99%

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Effects of exercise on lung lymph flow in sheep and goats during normoxia and hypoxia.

Coates¹,

O’Brodovich²,

Jefferies³

et al. 1984

J. Clin. Invest.

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As bstract. Vigorous exercise causes a marked increase in cardiac output with only a minimal increase in measureable pulmonary vascular pressures. These changes in pulmonary hemodynamics should affect lung water and solute movement.On nine occasions, we measured the effect of normoxic exercise on lung lymph flow in four sheep and two goats with chronic lymph fistulas (wt = 15-25 kg). In addition, lymph flow was also measured on five occasions in sheep during exercise at reduced barometric pressures (430 and 380 mmHg). During normobaria, the animals ran at 3-5 km/h with 0-10% elevation of the treadmill for 15 to 85 min. Exercise on average caused a 100% increase in cardiac output, a 140% increase in lung lymph flow, and a slight but significant reduction in lymph to plasma concentration ratio (l/p) for total protein and albumin (mol wt = 70,000). There was a significant linear correlation between lymph flow and cardiac output (r = 0.87, P < 0.01). There was no change in l/p for IgG (mol wt = 150,000) or IgM (mol wt = 900,000) and no significant change in mean pulmonary arterial (Ppa) or mean left atrial (Pla) pressures. Transition from normobaria to hypobaria caused an increase in Ppa but no change in Pla, cardiac output, or lymph flow. Exercise during hypobaria caused increases in lymph flow that were qualitatively similar to changes observed during normobaric exercise:These investigations were presented in part at

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effects of exercise on lung lymph flow in sheep and goats during normoxia and hypoxia.

Coates¹,

O’Brodovich²,

Jefferies³

et al. 1984

J. Clin. Invest.

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“…Circulatory arrest of the legs did not prevent the rise of venous pressure; hence venous return from the exercising muscles seemed unrelated to this response of venous pressure. Although inefficient removal of excess blood from the veins by the heart does not appear likely to account for the rise in pressure, the reduction of the volume of blood in the peripheral veins with exercise apparently does result in a high central blood volume (10).…”

Section: Methodsmentioning

confidence: 98%

The Mechanism of the Increased Venous Pressure With Exercise in Congestive Heart Failure*†

Wood¹

1962

J. Clin. Invest.

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“…Blood was sampled from the opposite brachial artery through an indwelling arterial needle, and was delivered to a cuvet densitometer by means of a polyethylene catheter and a motor-driven, suction syringe. The precise details of the method employed for cardiac output measurement, including the calibration technic, have been presented elsewhere (2). The cardiac output was calculated by utilizing the formula of Stewart and Hamilton after the inscribed dilution curves had been replotted on semilogarithmic paper.…”

Section: Methodsmentioning

confidence: 99%

The Effects of Autonomic Nervous System Inhibition on the Circulatory Response to Muscular Exercise*

Kahler¹,

Gaffney²,

Braunwald³

1962

J. Clin. Invest.

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One of the primary functions performed by the cardiovascular system is the delivery of oxygen and metabolic substrates to the peripheral tissues during varying levels of their activity. Accordingly, the manner in which the circulation is altered during muscular activity and the consideration that the cardiovascular response is mediated through the interaction of a number of mechanisms, prominent among which is the activity of the autonomic nervous system, are of interest. The present investigation was undertaken in an attempt to clarify the role of this mechanism in normal human subjects by determining the manner in which inhibition of the parasympathetic and the sympathetic divisions, or both, affected the circulatory response to exercise. Two pharmacologic agents were employed to produce functional inhibition of the autonomic nervous system; atropine was used to inhibit the parasympathetic division, and guanethidine, an effective adrenergic blocking agent (1), was used to interfere with the activity of the sympathetic division. METHODSThe investigations were carried out on six healthy male subjects whose ages ranged from 18 to 20 years. All studies were performed in the supine position, and measurements of heart rate, cardiac output, arterial blood pressure, and oxygen consumption were made at rest and during exercise in the four investigations performed on each subject. The first (control study) was performed without prior drug administration. Forty-five minutes after its completion, 2 mg of atropine sulfate was administered intravenously, and 5 minutes later the resting measurements were repeated, followed immediately by exercise. After these two studies oral guanethidine administration was begun at a daily dosage of 10 mg, which was progressively increased by 5 mg increments every other day for a period of 21 to 26 days. The * Presented in part at the meeting of the Eastern Section of the American Federation for Clinical Research, Philadelphia, January 11, 1962. maximum daily dosage reached ranged from 50 to 85 mg for each subject. The subjects were questioned about the side effects of guanethidine, and supine and standing blood pressures were recorded twice daily. The third study was performed at the end of the period of guanethidine administration while subjects were receiving the maximal doses. Forty-five minutes after completion of the third study, 2 mg of atropine sulfate was again administered intravenously, and five minutes later the fourth study was begun.Each subject had been thoroughly familiarized with the laboratory, the equipment, and the experimental procedure prior to the study, and all observations were carried out with the subj ects in the postabsorptive state. The control resting measurements were carried out approximately 20 minutes after insertion of the catheter and needles with the subject's feet placed on the pedals of a bicycle ergometer. Exercise consisted of pedaling the ergometer at a constant rate of 55 rpm at an external work load of approximately 1,500 foot-pounds per minute fo...

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The Effects of Exercise on Central Blood Volume in Man

Cited by 46 publications

References 22 publications

Effects of exercise on lung lymph flow in sheep and goats during normoxia and hypoxia.

Effects of exercise on lung lymph flow in sheep and goats during normoxia and hypoxia.

The Mechanism of the Increased Venous Pressure With Exercise in Congestive Heart Failure*†

The Effects of Autonomic Nervous System Inhibition on the Circulatory Response to Muscular Exercise*

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