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Rhythmic Aortic Contractions Induced by Electrical Stimulation In Vivo in the Rat.

Sahibzada N, Mangel AW, Tatge JE, Dretchen KL, Franz MR, Virmani R, Gillis RA - PLoS ONE (2015)

Bottom Line: In response to pulsatile pressure changes, the vessels undergo a 'passive' elastic dilatation-contraction cycle, described as a "Windkessel" effect.However, Mangel and colleagues have presented evidence that is contrary to this view.Electrical stimulation of the aorta evoked contractions that occur at a rate that is in the range of the animal's heartbeat and are suppressed by tetrodotoxin and the alpha-adrenergic receptor blocker, phentolamine.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmacology & Physiology, Georgetown University School of Medicine, 3900 Reservoir Road, NW, Washington, DC, 20007, United States of America.

ABSTRACT
For over a century, the behavior of the aorta and other large arteries has been described as passive elastic tubes in which no active contraction occurs in the smooth muscle wall. In response to pulsatile pressure changes, the vessels undergo a 'passive' elastic dilatation-contraction cycle, described as a "Windkessel" effect. However, Mangel and colleagues have presented evidence that is contrary to this view. They reported that in the rabbit, the aorta undergoes rhythmic 'active' (contraction) during the cardiac cycle; but these findings have been largely ignored. In the present study, we observed spontaneous contractions in synchrony with the heartbeat in another species (rat). In addition we demonstrate that aorta contractions are of neurogenic origin. Electrical stimulation of the aorta evoked contractions that occur at a rate that is in the range of the animal's heartbeat and are suppressed by tetrodotoxin and the alpha-adrenergic receptor blocker, phentolamine. Altogether, these findings indicate that aortic contractions are under neural control from the heart.

No MeSH data available.


Related in: MedlinePlus

Suppression of electrically evoked aortic contractions by phentolamine.(A) Rhythmic phasic contractions elicited in the aorta by a 5s pulse train (1.7 Hz, 2 msec, 10 volts), the amplitude of which was reduced by topical application of 1 mL of 1 mM phentolamine (B). (C) Graph illustrating the mean change in pressure from baseline induced by electrical stimulation of the aorta in the absence and presence of phentolamine (n = 4). * Significance p<0.05.
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pone.0130255.g006: Suppression of electrically evoked aortic contractions by phentolamine.(A) Rhythmic phasic contractions elicited in the aorta by a 5s pulse train (1.7 Hz, 2 msec, 10 volts), the amplitude of which was reduced by topical application of 1 mL of 1 mM phentolamine (B). (C) Graph illustrating the mean change in pressure from baseline induced by electrical stimulation of the aorta in the absence and presence of phentolamine (n = 4). * Significance p<0.05.

Mentions: To determine the nature of the neurally induced aorta contraction evoked by electrical stimulation, we evaluated whether topical application of the non-specific α-adrenergic receptor blocker, phentolamine would prevent the response. Following electrically evoked control aortic contractions; 1ml of 1.0 mM phentolamine was topically applied to the aorta. As can be noted in Fig 6, phentolamine application in all but one rat significantly reduced or eliminated the electrically induced aortic contractions. Additionally, when the phentolamine application reduced the response but failed to abolish it, subsequent application of the TTX solution inhibited the remaining electrically induced contraction of the aorta.


Rhythmic Aortic Contractions Induced by Electrical Stimulation In Vivo in the Rat.

Sahibzada N, Mangel AW, Tatge JE, Dretchen KL, Franz MR, Virmani R, Gillis RA - PLoS ONE (2015)

Suppression of electrically evoked aortic contractions by phentolamine.(A) Rhythmic phasic contractions elicited in the aorta by a 5s pulse train (1.7 Hz, 2 msec, 10 volts), the amplitude of which was reduced by topical application of 1 mL of 1 mM phentolamine (B). (C) Graph illustrating the mean change in pressure from baseline induced by electrical stimulation of the aorta in the absence and presence of phentolamine (n = 4). * Significance p<0.05.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4489007&req=5

pone.0130255.g006: Suppression of electrically evoked aortic contractions by phentolamine.(A) Rhythmic phasic contractions elicited in the aorta by a 5s pulse train (1.7 Hz, 2 msec, 10 volts), the amplitude of which was reduced by topical application of 1 mL of 1 mM phentolamine (B). (C) Graph illustrating the mean change in pressure from baseline induced by electrical stimulation of the aorta in the absence and presence of phentolamine (n = 4). * Significance p<0.05.
Mentions: To determine the nature of the neurally induced aorta contraction evoked by electrical stimulation, we evaluated whether topical application of the non-specific α-adrenergic receptor blocker, phentolamine would prevent the response. Following electrically evoked control aortic contractions; 1ml of 1.0 mM phentolamine was topically applied to the aorta. As can be noted in Fig 6, phentolamine application in all but one rat significantly reduced or eliminated the electrically induced aortic contractions. Additionally, when the phentolamine application reduced the response but failed to abolish it, subsequent application of the TTX solution inhibited the remaining electrically induced contraction of the aorta.

Bottom Line: In response to pulsatile pressure changes, the vessels undergo a 'passive' elastic dilatation-contraction cycle, described as a "Windkessel" effect.However, Mangel and colleagues have presented evidence that is contrary to this view.Electrical stimulation of the aorta evoked contractions that occur at a rate that is in the range of the animal's heartbeat and are suppressed by tetrodotoxin and the alpha-adrenergic receptor blocker, phentolamine.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmacology & Physiology, Georgetown University School of Medicine, 3900 Reservoir Road, NW, Washington, DC, 20007, United States of America.

ABSTRACT
For over a century, the behavior of the aorta and other large arteries has been described as passive elastic tubes in which no active contraction occurs in the smooth muscle wall. In response to pulsatile pressure changes, the vessels undergo a 'passive' elastic dilatation-contraction cycle, described as a "Windkessel" effect. However, Mangel and colleagues have presented evidence that is contrary to this view. They reported that in the rabbit, the aorta undergoes rhythmic 'active' (contraction) during the cardiac cycle; but these findings have been largely ignored. In the present study, we observed spontaneous contractions in synchrony with the heartbeat in another species (rat). In addition we demonstrate that aorta contractions are of neurogenic origin. Electrical stimulation of the aorta evoked contractions that occur at a rate that is in the range of the animal's heartbeat and are suppressed by tetrodotoxin and the alpha-adrenergic receptor blocker, phentolamine. Altogether, these findings indicate that aortic contractions are under neural control from the heart.

No MeSH data available.


Related in: MedlinePlus