Chronic antihypertensive treatment with captopril plus hydrochlorothiazide improves aortic distensibility in the spontaneously hypertensive rat

Abstract

Adult male spontaneously hypertensive rats (SHR) were given captopril plus hydrochlorothiazide mixed in the diet for 10 weeks. Calculated daily doses were 44 mg kg−1 per day for captopril, and 22 mg kg−1 per day for hydrochlorothiazide. Separate groups received captopril or hydrochlorothiazide alone, at similar doses, or no treatment. A final group of WKY normotensive rats received no drug. Systolic arterial blood pressure, measured at regular intervals throughout the 10 weeks' period was lowered but not normalized, in groups receiving either captopril plus hydrochlorothiazide, or captopril alone, but not in the group receiving hydrochlorothiazide alone. Following pentobarbitone anaesthesia, systolic arterial blood pressure, measured in the femoral artery, was found to be lower in all treated groups, but the greatest effect was observed in SHR previously treated with captopril plus hydrochlorothiazide. Aortic pulse wave velocity was also lower in treated SHR, and once again the greatest decrease was observed in the group previously treated with captopril plus hydrochlorothiazide. Following pithing, systolic arterial blood pressures were similar in all SHR groups. Aortic pulse wave velocity was lower in pithed rats previously treated with captopril and hydrochlorothiazide. In conclusion, antihypertensive treatment of SHR produces falls in blood pressure and pulse wave velocity, an indicator of aortic distensibility. Results in pithed rats suggest that treatment with the combination of captopril plus hydrochlorothiazide may increase aortic distensibility independently of blood pressure.

Persistent effect of early, brief angiotensin-converting enzyme inhibition on segmental pressure dependency of aortic stiffness in spontaneously hypertensive rats

“…In this regard, several authors have reported that the reversal of hypertension by chronic ACEi and angiotensin II receptor blockade [9,[11][12][13] could lower systolic arterial BP and aortic stiffness as measured by pulse wave velocity (PWV). The reduction in aortic PWV was associated with structural changes in the vessel wall in both SHR [7] and rat renovascular models of hypertension [14], both associated with a reduction in BP.…”

Constrictor and Dilator Effects of Angiotensin II on Cerebral Arterioles

“…26 The explanation for this may lie in the relative lack of sensibility of rat microvasculature to ACE inhibitors (unless associated with salidiuretic treatment). 27 It has previously been reported that degradation products of angiotensin such as the hexapeptide Ang II-(3-8) 18 rather than Ang II itself produce arteriolar vasomotor effects. Our experiments neither confirm nor refute this possibility.…”

Determination of Aortic Elastic Modulus by Pulse Wave Velocity and Wall Tracking in a Rat Model of Aortic Stiffness

“…Measurement of pressure pulse wave velocity (PWV) provides values for elastic modulus via the Moens-Korteweg equation. This was first developed to measure aortic elasticity in large mammal species (humans [5]and dogs [6]), then adapted to smaller species such as the rat [7, 8]. More recently, ultrasound technology (using a wall echo-tracking device) has been developed to follow the changes in diameter following a change in pulse pressure.…”