Effects of Testosterone Deficiency and Angiotensin II–Induced Hypertension on the Biomechanics of Intramural Coronary Arteries

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  • Attila Jósvai, MD , Marianna Török, MD, Máté Mátrai, MD, Béla Székács, MD, PhD, DSc , György L. Nádasy, MD, PhD , Szabolcs Várbíró, MD, PhD 

Published: October 13, 2020

Abstract

Background

Andropause and hypertension also increase the risk of coronary artery damage.

Aim

To investigate the effect of testosterone deficiency and hypertension on intramural coronary vessels.

Methods

4 groups of 8-week-old Sprague-Dawley rats were studied: control male (Co, n=10), orchidectomized male (OCT, n=13), angiotensin (AII) hypertensive male (AII, n=10), and AII hypertensive and OCT (AII + OCT, n=8). Surgical orchidectomy was performed, and an osmotic minipump was inserted for chronic angiotensin II infusion (100 ng/min/kg). After 4 weeks, spontaneous tone and biomechanical properties of the intramural coronary resistance artery were investigated in vitro, by pressure microarteriography.

Outcomes

Morphology and biomechanics of the intramural coronaries were evaluated: the outer diameter, wall thickness–to–lumen diameter ratio, and tangential wall stress in the contracted and relaxed states.

Results

The outer diameter was reduced in OCT and AII + OCT groups (on 50 mmHg 315 ± 20 Co; 237 ± 21 OCT; 291 ± 16 AII, and 166 ± 12 μm AII + OCT). The increased wall thickness–to–lumen diameter ratio resulted in lower tangential wall stress in AII + OCT rats (on 50 mmHg 19 ± 2 Co; 24 ± OCT; 26 ± 5 AII, and 9 ± 1 kPa AII + OCT). Spontaneous tone was increased in the hypertensive rats (AII and AII + OCT groups) (on 50 mmHg 7.7 ± 1.8 Co; 6.1 ± 1.4 OCT; 14.5 ± 3.0 AII, and 17.4 ± 4.1 % AII + OCT).

Clinical Implications

Andropause alone can be considered as a cardiovascular risk factor that will further exacerbate vascular damage in hypertension.

Strengths & Limitations

A limitation of our study is that it was performed on relatively young rats, and the conclusions might not apply to coronary remodelling in older animals with slower adaptation processes.

Conclusions

Testosterone deficiency and hypertension damage the mechanical adaptation of the vessel wall additively: double noxa caused inward eutrophic remodeling and increased tone.

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WellsRX TeamEffects of Testosterone Deficiency and Angiotensin II–Induced Hypertension on the Biomechanics of Intramural Coronary Arteries