Different Responses of Arterial Stiffness between the Aorta and the Iliofemoral Artery during the Administration of Phentolamine and Atenolol in Rabbits

Abstract

The mechanism underlying the stiffness of the aorta and iliofemoral artery that is required to maintain blood pressure (BP) is unclear. A new stiffness index of the aorta (aBeta) and iliac-femoral arteries (ifBeta) was defined by applying the cardio-ankle vascular index (CAVI). We compared changes in stiffness of the two arteries in response to reduced BP, due to the non-selective adrenergic blocker phentolamine and the 1 adrenergic blocker atenolol, in rabbits.Methods: Pressure waves at the origin (oA) and distal ends of the aorta (dA) and the distal end of the left femoral artery (fA) were recorded simultaneously using three pressure sensors in 25 anesthetized rabbits. Phentolamine (50 µg/kg/min) and atenolol (10 mg/kg/min) were infused for 2 min. The pulse wave velocity (PWV) in each artery was determined; aBeta, ifBeta, and whole Beta (aifBeta) were calculated by the following formula; Beta 2 /PP ln(SBP/DBP) PWV 2 ( : blood density; SBP, SBP, and PP: systolic, diastolic, and pulse pressures, respectively).Results: SBP and DBP at oA, dA, and fA decreased by the administration of phentolamine and atenolol, with and without decreased total peripheral vascular resistance. After phentramine infusion, cardiac output (CO), aBeta, and aifBeta increased, while ifBeta decreased. After infusion of atenolol, CO decreased, while aBeta, ifBeta, and aifBeta remained unchanged. Conclusion:The contradictory reactions of aBeta and ifBeta to phentolamine suggest that the stiffness of the aorta and ilio-femoral artery is regulated separately during decreased BP induced by phentolamine, but not by atenolol.phase and sends it to peripheral tissue during the diastolic phase 3) , which plays a role as the afterload of the left ventricle. These functions are fulfilled by arterial stiffness, but there was no suitable arterial stiffness index to evaluate such vascular function, especially for clinical use. Pulse wave velocity (PWV) has been a widely-used index for reflecting arterial stiffness in clinical studies 1,[4][5][6][7] . However, PWV does not properly Copyright©2021 Japan Atherosclerosis Society This article is distributed under the terms of the latest version of CC BY-NC-SA defined by the Creative Commons Attribution License.

Real-Time Evaluation of Regional Arterial Stiffening, Resistance, and Ocular Circulation During Systemic Administration of Adrenaline in White Rabbits

“…Contradictory responses of arterial stiffness between the elastic artery and the muscular artery were confirmed by an experimental study of α-receptor and β-receptor blockade in rabbits. 9 In a clinical investigation of the regional PWV in patients with diabetes and ischemic heart disease, arterial stiffness was found to play different roles in the muscular and elastic arteries. 43 This finding may be misleading in attempts to determine the relationship between systemic and ocular blood flows in adrenaline loading.…”

“…Nevertheless, the number of MBR readings per time point was low. Finally, it was reported that the length ratio of elastic and muscle arteries differs between rabbits and humans, 9 so further investigation in humans is necessary. Additional studies are also warranted to investigate the relationships among systemic hemodynamics, function, and ocular circulation under the systemic stimulation of adrenaline receptors.…”

“…The ha-PWV, hf-PWV, and fa-PWV were measured using the distance of the two pressure sensors between the ha, hf, and fa, and the differences in the peak times of two pressure waves were measured between the ha, hf, and fa, respectively. 9 We calculated the ha-PWV by using the blood pressure of the brachial and tibial arteries, because the time between the closing sound of the aortic valve and the notch of the brachial pulse wave is estimated to be equal to the time between the opening sound of the aortic valve and the rise of the brachial pulse wave. 21 …”

“…An experimental study of α adrenaline receptor and β adrenaline receptor blockade in rabbits revealed contradictory responses of arterial stiffness between the elastic artery and muscular artery. 9 It has been unclear whether regional arterial stiffness and resistance would strongly influence rabbit ocular microcirculation under systemically administered adrenaline loading and whether the sites of arterial stiffness and resistance would change depending on the dose of adrenaline.…”

Assessment of Arterial Stiffness Using the Cardio-Ankle Vascular Index – What We Know and What We Strive for

“…Katsuda и соавт. [14], в котором оценивали параметр жесткости артериальной стенки β в эксперименте на 2-х разных участках (на аорте и на подвздошно-бедренной артерии) на фоне воздействия неселективного α-адренергического блокатора фентоламина и β 1 -адренергического блокатора атенолола. Противоречивые реакции данного показателя (повышение в аорте и снижение на подвздошно-бедренной артерии) предполагают, что жесткость аорты и подвздошно-бедренной артерии регулируется отдельно во время снижения АД, вызванного фентоламином.…”