Phenylephrine induces relaxation of longitudinal strips from small arteries of goat legs

Marconi, Kawin Padmaja; Bharathi, B. Suman; Venis, Alen Major; Raj, Renu; Amirtham, Soosai Manickam; Subramani, Sathya

doi:10.1101/2019.12.18.881003

Cited by 1 publication

(4 citation statements)

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“…It is seen that there is no significant change in mean pressure or pulse pressure till the radius reduces from 5 mm to about 2 mm. This evidence must be seen in the context of the fact that aorta has both longitudinal and circular smooth muscle and adrenergic stimulation causes constriction of both types of muscle 11,19 . On the other hand, for the entire range of reduction in compliance, there was no change in mean aortic pressure, but the pulse pressure increased with reducing compliance almost linearly.…”

Section: Resultsmentioning

confidence: 99%

“…Small arteries also have circular and longitudinal smooth muscle 11 . They too must have a defined resistance and compliance.…”

Section: Discussionmentioning

confidence: 99%

“…One aim of this study is to assess the effect of adrenaline, a known vasoconstrictor on aortic resistance and compliance as compared to small arteries. Aortic smooth muscle, both circular and longitudinal, contract in response to adrenergic stimulation while in the arterioles the circular muscles contract and longitudinal muscles relax 11 . The questions we asked were whether the contractile response of the smooth muscle in the walls of aorta (and large arteries) leads to (1) an acute change in compliance, or (2) a change in resistance, or (3) both.…”

Section: Introductionmentioning

confidence: 99%

“…Loss of elasticity is a slow aging process, occurring over years 8,9,10 . However, aorta has considerable smooth muscle in their tunica media, interspersed with which the elastic tissue is found 11 . The role of smooth muscle present in the walls of aorta and large arteries is less appreciated 12 .…”

Section: Introductionmentioning

confidence: 99%

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Vasoconstriction in isolated goat aorta does not increase mean aortic pressure

Gangadharan

Aravindhan

Jebaraj

et al. 2021

Preprint

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Vasoconstriction in small arteries and arterioles is known to increase resistance to flow, while vasoconstriction in large arteries and aorta is known to decrease their compliance. Besides this general understanding, there is no systematic documentation on what happens to small artery compliance and large artery resistance during vasoconstriction and the corresponding alterations in vascular pressure. The aim of the study is to assess the effect of adrenaline on goat aortae and small arteries in terms of resistance and compliance.Isolated goat aortae and small arteries were perfused with a pulsatile pump and lumen pressure was recorded before and after addition of adrenaline. In the aortae, systolic pressure increased, diastolic pressure decreased, pulse pressure increased (p = 0.018, WSR); but the mean pressure remained the same (p = 0.357, WSR). Small artery vasoconstriction caused an increase in systolic, diastolic and mean pressures (p = 0.028, WSR). Using length, radius, and thickness data from the tissues and the tubes of the experimental set-up, electrical models were simulated to understand the biological data. The simulations allow us to infer that vasoconstriction in aorta leads to a reduction in compliance, but an increase in resistance if any, is not sufficient to change the mean aortic pressure. On the other hand, vasoconstriction in small arteries increases resistance, but a decrease in compliance if any, does not affect any of the four pressure parameters measured. Vasoconstriction in aorta decreases compliance and therefore increases pulse pressure but does not change resistance significantly enough to alter mean pressure.Key Points SummaryThe main aim of the study is to understand where exactly resistance (R) and compliance (C) components of the vasculature occur. There is no definitive evidence for the effect of large artery vasoconstriction on resistance and hence the mean arterial pressure.The manuscript presents biological experiments studying the pressure response of goat aorta and small arteries to adrenaline (invitro) and the interpretations using equivalent electrical models.The study shows that in aorta and large arteries, vasoconstriction does not lead to a reduction in lumen diameter sufficient to cause a rise in resistance and mean pressure as compared to small arteries.Knowledge of exact location of R and C in the arterial tree enables re-assessment of the differential action of vasoactive drugs on resistance versus compliance vessels once we resolve beat-to-beat R and C changes in response to a drug. This way antihypertensive therapy can be tailored to address the specific cause of the type of hypertension.

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Section: Resultsmentioning

confidence: 99%

“…Small arteries also have circular and longitudinal smooth muscle 11 . They too must have a defined resistance and compliance.…”

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%