Veins and venous tone

Folkow, Björn; Mellander, Stefan

doi:10.1016/0002-8703(64)90308-4

Cited by 82 publications

(25 citation statements)

References 35 publications

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“…This venoarteriolar reflex has been reported to be able to reduce the lower limb blood flow up to 30-45% during orthostatic stress (Hendriksen & Sjersen, 1977;Skagen & Bonde-Petersen, 1982;Hendriksen & Skagen, 1988). A myogenic response in the resistance arterioles of the dependent regions (in response to increased transmural pressure) (Folkow, 1962;Mellander et al 1964;Folkow & Mellander, 1964) may also contribute to the rise in vascular resistance, but this effect is now thought to be less important than the venoarteriolar reflex. In contrast to the venoarteriolar reflex the myogenic response is not regarded as a sustained response (Johnson, 1980;R adegran & Saltin, 1998).…”

Section: Regulation Of Blood Pressure and Venous Capacitance In Healtmentioning

confidence: 99%

Pathophysiological basis of orthostatic hypotension in autonomic failure

Smit

Halliwill²,

Low

et al. 1999

The Journal of Physiology

326

209

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Patients with autonomic failure may be seriously incapacitated in activities of daily living due to orthostatic hypotension. Their low blood pressure is ascribed to a defective increase in arterial resistance and an excessive venous pooling upon standing. Effective pharmacological treatment is now available, but may aggravate supine hypertension and have other undesirable effects. Additionally, pharmacological treatment is less successful for hypotension with physical exercise or in warm surroundings (Bannister & Mathias, 1992). Non-pharmacological measures are regarded as a cornerstone in the treatment of orthostatic hypotension. These measures consist of chronic expansion of the extracellular volume or reducing the vascular volume in which pooling occurs (Bannister & Mathias, 1992). The latter includes protective measures like physical countermanoeuvres which can be applied by those patients with no major additional neurological and musculo-skeletal disorders, and external support garments which can be recommended to all patients. We reasoned that selection and use of appropriate protective measures would be facilitated by understanding the fundamental physiological mechanisms that prevent excessive orthostatic pooling in healthy subjects, why these mechanisms fail in patients with autonomic failure, and how these protective measures work. Therefore we reviewed the literature and summarized the available data about the amount and location of venous pooling in patients with autonomic failure and the effectiveness of physical countermanoeuvres and external support garments.

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Section: Regulation Of Blood Pressure and Venous Capacitance In Healtmentioning

confidence: 99%

Pathophysiological basis of orthostatic hypotension in autonomic failure

Smit

Halliwill²,

Low

et al. 1999

The Journal of Physiology

326

209

View full text Add to dashboard Cite

show abstract

“…Further, since the forearm is principally composed of skeletal muscle and the-hand skin, an explanation is provided for the observation that veins of the forearm, studied as a whole, appear less reactive to stimuli than veins of the hand. An explanation also is provided for This work was presented in part at the 52nd annual meeting of the Federation of Ameriran Societies for Experimental INTRODUCTION It is well established that the distensibility of the capacitance vessels can be diminished actively through reflexes mediated by the sympathetic nervous system (1)(2)(3)(4)(5)(6)(7)(8)(9)(10); the traditional view is that this constriction occurs equally in all components of the peripheral venous system. Recently, however, studies in experimental animals have suggested that there is a different relative responsiveness of certain venous segments to nerve stimulation.…”

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confidence: 99%

Comparison of the reflex reactivity of skin and muscle veins in the human forearm

Zelis¹,

Mason²

1969

J. Clin. Invest.

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A B S T R A C T To determine the relative participation of skin and muscle capacitance beds of the forearm in venomotor reflexes, epinephrine iontophoresis was combined with forearm plethysmography so that the volume of muscle veins could be estimated simultaneously with the volume of cutaneous veins, at a constant venous pressure. With this technique not only are the cutaneous veins markedly constricted but they also are prevented from filling since skin blood flow is abolished. In 10 normal subjects, the venous volume in the elevated control forearm at a congesting pressure of 30 mm Hg (VV[30]) was 3.16 ±0.30 SEM cc/100 cc, while in the iontophoresed arm it was 2.54 ±0.31 cc/100 cc.Thus the forearm cutaneous VV[30] was 1.62 cc/100 cc. With a deep breath, ice to the forehead, and leg exercise, and cutaneous VV[30] decreased 19.8% (P < 0.01), 36.6% (P < 0.01), and 32.6% (P < 0.02), respectively, whereas the muscle VV [30] was not altered significantly. Similar results were observed using the isolated forearm technique and a deep muscle vein. The infusion of epinephrine intra-arterially did not decrease reflex venomotor reactivity until cutaneous blood flow was completely suppressed, indicating that the inability of the veins to react in the iontophoresed arm was not the result of epinephrine diffusion into the muscle bed. Thus, these results indicate that, in the forearm, only cutaneous veins participate in venomotor reflexes. Further, since the forearm is principally composed of skeletal muscle and the-hand skin, an explanation is provided for the observation that veins of the forearm, studied as a whole, appear less reactive to stimuli than veins of the hand. An explanation also is provided for This work was presented in part at the 52nd annual meeting of the Federation

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“…In certain circumstances such as carotid occlusion, venous outflow and arterial inflow are assumed to be equal, but this rule could not be applied to the situation, such as rapid and phasic responses during electrical stimulation of the brain. 20 …”

Section: Resultsmentioning

confidence: 99%

Comparison of Vasoconstrictor Responses in Functionally Different Organs Induced by Stimulation of Mesencephalic Pressor Area

et al. 1966

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Autonomic nerve influences on various vascular beds have been believed to be diffuse and undifferentiated. But recent studies have disclosed some evidences suggesting that reflex adjustment induced by the cardiovascular proprioceptors really gives different effects on blood distribution among each vascular section. In this report, an attempt was made to clarify the anatomical basis, on which the sympathetic control of functionally different vascular beds can be changed selectively.The dog was secured in a stereotaxic instrument. The central gray stratum and reticular formation of the mesencephalon were stimulated repeatedly, and responses of circulation in the kidney, intestine and lower extremity were observed simultaneously. Three vascular circuits were perfused at constant flow, and the changes in the resistances of the vessels were indicated by changes in the perfusion pressures.Stimulation in areas involved resulted in increased systemic blood pressure accompanied by the vasoconstriction in the kidney, intestine and lower extremity which was pretreated by atropine. The changes in perfusion pressures by the electrical stimulation were simultaneously recorded from 2 of these vascular circuits.Constrictor responses obtained at various stimulation sites within the areas involved were compared with each other. The points giving maximal vasoconstriction in the kidney, intestine and lower extremity were anatomically separate.On stimulation of the areas dorsal, intense renal vasoconstriction was observed, while maximum vasoconstriction in the intestine and lower extremity were obtained in the ventral portion of the areas.It is concluded that there is relatively anatomical separation in autonomic nerve centers responsible for vasoconstrictor activity in functionally different organs.UTONOMIC nervous control of peripheral vascular tone has been considered to be fairly diffuse and undifferentiated in its function. But it has frequently encountered some difficulty to accept that complex cardiovascular adjustment can be induced simply by uniformly discharged autonomic

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Veins and venous tone

Cited by 82 publications

References 35 publications

Pathophysiological basis of orthostatic hypotension in autonomic failure

Pathophysiological basis of orthostatic hypotension in autonomic failure

Comparison of the reflex reactivity of skin and muscle veins in the human forearm

Comparison of Vasoconstrictor Responses in Functionally Different Organs Induced by Stimulation of Mesencephalic Pressor Area

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