Range of the Sympathetic Control of the Dog Femoral Artery

Abstract

Femoral arterial diameter and pressure were measured in anesthetized dogs. Immediately after section of the ipsilateral lumbar sympathetic chain the artery dilated, reaching a maximum of 122.0% (±0.56 SEM) of resting diameter within 30 to 40 seconds. Later the diameter diminished, stabilizing at 104.3% (±1.8 SEM) of resting diameter within 15 minutes. Stimulation of the peripheral stump of the sympathetic chain induced frequency-dependent constriction, the frequency-response curve being hyperbolic. The average maximal response was 13.42% (± 1.19 SEM) of the resting diameter. These changes were not dependent on suprarenal secretion, blood flow, or changes in distal vascular bed resistance. The contraction of the artery was slow. The half-time of stabilized contraction was 21.6 seconds at a stimulus frequency of 1/sec and 36.8 seconds at 25/sec. The half-time of relaxation was shorter (10.7 seconds and 21.5 seconds, respectively) and also frequency-dependent. A significant dilatation, after stimulation, inversely proportional to the stimulation frequency, occurred after low-frequency stimulations. The time course of contraction suggests the activation of individual smooth muscle layers successively more remote to the nerve endings, possibly due to diffusion of transmitter liberated at the nerve endings by stimulation.From the Department of Cardiovascular Physiology, Institute of Normal and Pathological Physiology, Slovak Academy of Sciences, Bratislava..

Low arterial compliance in young African-American males

“…In the current investigation, the lower arterial compliance was seen in the presence of an augmentation in sympathovagal balance. This augmentation has been shown to further reduce distensibility of small, medium, and large arteries, resulting in a tonic restraint of elastic and resistance type vessels (3,6,11,24,43). Independently and in combination, the loss of arterial compliance and alterations in autonomic function are associated with increased HT risk.…”

Crucial role of endothelium in the vasodilator response to increased flow in vivo.

“…The maximum levels of diameter reduction induced in our study were comparable to those obtained by profound sympathetic stimulation in situ. 24 It is conceivable that circulating EDRF released at the luminal side of intact endothelium, proximal to the denuded area, can exert a dilator response in the denuded segment. However, there is evidence that a plasma factor (or factors) may inactivate the EDRF.…”

Exercise training favourably affects autonomic and blood pressure responses during mental and physical stressors in African-American men

“…[47][48][49] The improvement in BRS in this investigation could be in part due to a lesser sympathetic modulation and a well-known mediator of vascular stiffness. 20,50,51 Arterial compliance Loss of AC during sympathetic stimuli leads to exaggerated increases in an a 2 -adrenergic-mediated vasoconstriction and/or decreases in b 2 -adrenergicmediated vasodilation, both of which contribute to increases in arterial stiffness. Augmented and/or exaggerated sympathetic activity has been shown to further reduce distensibility of small, medium and large arteries, [49][50][51][52][53] and is a common denominator for risk factors related to hypertension.…”

“…20,50,51 Arterial compliance Loss of AC during sympathetic stimuli leads to exaggerated increases in an a 2 -adrenergic-mediated vasoconstriction and/or decreases in b 2 -adrenergicmediated vasodilation, both of which contribute to increases in arterial stiffness. Augmented and/or exaggerated sympathetic activity has been shown to further reduce distensibility of small, medium and large arteries, [49][50][51][52][53] and is a common denominator for risk factors related to hypertension. [54][55][56] Our prior study, and that of others, has shown that a strong relationship exists between .…”