title: Hypotensive effects of captopril on physical properties of the arterial system in young and adult rats.
abstract: We determined the acute effects of the angiotension converting enzyme inhibitor captopril on the arterial mechanics in rats at different ages, based on the exponentially tapered T-tube model. Male Wistar-Kyoto rats aged 4 and 12 months were individually referred to as young (n = 8) and adult rats (n = 8) and were anesthetized and thoractomized. The pulsatile aortic pressure and flow signals before and after the administration of captopril (20 mg/kg, i.p.) were measured by a high-fidelity pressure sensor and an electromagnetic flow probe, respectively. In each age group, captopril showed little change in basal heart rate as well as cardiac output. However, captopril produced a drop of 15% in mean aortic pressure in young and a fall of 12% in adult rats. In addition. captopril reduced total peripheral resistance by 21% in young and by 23% in adult animals. As for the pulsatile nature of the arterial system, captopril had increased wave transit time of the lower body circulation of 10% in young and of 12% in adult rats. By contrast, captopril reduced wave reflection factor by 22% in young and by 25% in adult animals. In conclusion, the converting enzyme inhibitor captopril has a stiffness-decreasing effect on Windkessel vessels and a dilated effect on resistance arterioles in either young or adult rats. No age dependence of vascular response and reflex tachycardia to captopril has been found in rats between 4 and 12 months.
authors.affiliation: Department of Physiology, College of Medicine, National Taiwan University, Taipei. kcchang@ha.mc.ntu.edu.tw
authors.forename: K C
authors.initials: KC
authors.lastname: Chang
authors.forename: Y I
authors.initials: YI
authors.lastname: Peng
authors.forename: Y F
authors.initials: YF
authors.lastname: Tsai
authors.forename: Y Z
authors.initials: YZ
authors.lastname: Tseng
authors.forename: H I
authors.initials: HI
authors.lastname: Chen
mesh_terms: D000375:Aging / Q000502:physiology*; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000494:pharmacology*; D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology*; D001011:Aorta / Q000187:drug effects* / Q000502:physiology; D001835:Body Weight; D002216:Captopril / Q000494:pharmacology*; D006439:Hemodynamics; D008297:Male; D051381:Rats; D011921:Rats, Inbred WKY
chemical_list: D000806:Angiotensin-Converting Enzyme Inhibitors; D000959:Antihypertensive Agents; D002216:Captopril