Chronic converting enzyme inhibition normalizes QT interval in aging rats

Abstract

The aim of the present study was to investigate the effects of converting enzyme inhibition by captopril on ECG parameters in aged rats. Four-month-old male rats received captopril dissolved in tap water (0.5 mg/l) or tap water for 2 or 20 months. At the end of treatment, under anesthesia, RR and PR interval, P wave and QRS duration, QT and corrected QT interval were measured in all animals. On the following day, chronic ECG (lead II) recordings were performed to quantify supraventricular (SVPB) or ventricular premature beats (VPB). After sacrifice, the hearts were removed and weighed. RR interval was similar in young and untreated aged rats, but significantly larger in aged rats treated with captopril. P wave and QRS length did not differ among groups. PR interval was significantly larger in old than in young rats and was not affected by captopril. Corrected QT interval was larger in aged than in young rats (117 ± 4 vs 64 ± 6 ms, P<0.05) and was reduced by captopril (71 ± 6 ms, P<0.05). VPB were absent in young rats and highly frequent in untreated old animals (8.4 ± 3.0/30 min). Captopril significantly reduced VPB in old rats (0.3 ± 0.1/30 min, P<0.05). The cardiac hypertrophy found in untreated aged rats was prevented by captopril (3.44 ± 0.14 vs 3.07 ± 0.10 mg/g, P<0.05). The beneficial effects of angiotensin converting enzyme inhibition on the rat heart during the aging process are remarkable.

Antihypertensive Effects of Roselle-Olive Combination in L-NAME-Induced Hypertensive Rats

“…On the other hand, it decreased heart rate, QRS, QT, QT c , and R-amplitude as compared to normotensive rats. Impairment of ECG parameters by L-NAME goes in line with the findings of Chaswal et al [ 54 ] and also could be attributed to the effect of the decreased NO production on vascular smooth tone [ 55 ]. Remarkably, lisinopril and all doses of Roselle-Olive ameliorated the L-NAME-induced changes in ECG parameters after 30 days of treatment (Figures 2 and 3 ).…”

Efficacy of Female Rat Models in Translational Cardiovascular Aging Research

“…In addition, aging is also associated with an increase in the percentage of incidence of atrial fibrillation [ 60 , 69 ]. In male rats, age-associated increases in cardiac fibrosis as well as the changes in gap junction morphology have been hypothesized to cause changes in cardiac conduction in addition to the incidence of arrhythmias and death [ 68 , 70 ]. As humans age, there is an increase in the EKG abnormalities which are associated with increased mortality [ 71 ].…”

“…Similar alterations in electrocardiogram parameters have also been found in aging rats. In male Wistar rats, the PR and corrected QT intervals were found to increase with age [ 70 ]. Alterations in aging electrocardiogram parameters have been shown to be rat strain dependent and could only be detected subsequently to heart failure as in male SHHF/Mcc-cp rat strain at 19 months of age [ 77 ].…”

Rat Electrocardiography and General Anesthesia

“…One study describing HR in isolated rat hearts did not reveal any significant deviation, in terms of tachycardia or bradycardia [105]. Interesting differences were also found between young and old rats under tribromoethanol anesthesia, where higher values prevailed in older rats (405 ± 11 beats/ min vs. 381 ± 1 beats/min) [106]. Unfortunately, these comparisons are only from males and without a description of the adaptation of the animals to the LD cycle.…”