Effect of enalapril treatment on the sensitivity of cardiopulmonary reflexes in rats with myocardial infarction.
1. The aim of the present study was to evaluate the effect of treatment with enalapril on the sensitivity of cardiopulmonary reflexes 30 days after myocardial infarction in Wistar rats. 2. Animals were divided into four groups: (i) sham operated, receiving vehicle (SHAM); (ii) infarcted, receiving vehicle (0.9% NaCl; INF); (iii) sham operated, receiving enalapril (SHAME); and (iv) infarcted, receiving enalapril (INFE). 3. Enalapril was administered at a dose of 10 mg/kg per day. Serotonin (4-32 microg/kg, i.v.) was administered in order to activate the Bezold-Jarisch reflex, which was estimated as the percentage of reduction in heart rate. 4. The volume-sensitive cardiopulmonary reflex was induced by saline overload and evaluated as the percentage increase in sodium and volume renal excretion. At the end of the experiments, rats were killed and hearts excised to estimate the size of the infarction. The weight of the kidneys, lungs, liver and cardiac chambers as ratios of bodyweight was used to estimate the extent of hypertrophy. 5. The results showed an impairment in the sensitivity of the cardiopulmonary reflexes in the INF group compared with the SHAM and SHAME groups. We observed right ventricle and pulmonary hypertrophy, a reduction in mean and systolic arterial pressure and an increase in heart rate in INF animals. In the INFE group, nearly all the parameters were normal compared with the INF group, except for systolic arterial pressure, which was only partially improved. 6. The main finding of the present study was that treatment with enalapril normalized the sensitivity of the cardiopulmonary reflexes, which could be due, in part, to the reduction of cardiac hypertrophy. The present study provides information about the beneficial effects of the angiotensin-converting enzyme inhibitors by normalizing the cardiopulmonary reflexes involved with the regulation of volume and sodium, as well as control of arterial pressure and heart rate in infarcted animals.
Andrade
T U
TU
Department of Pharmacy, University Centre of Vila Velha, Vila Velha, Brazil.
Pinto
V D
VD
Medeiros
A R S
AR
Abreu
G R
GR
Moysés
M R
MR
Sampaio
K N
KN
Bissoli
N S
NS
D000806:Angiotensin-Converting Enzyme Inhibitors / Q000494:pharmacology* / Q000627:therapeutic use; D000818:Animals; D017704:Baroreflex / Q000187:drug effects; D001794:Blood Pressure / Q000187:drug effects; D006332:Cardiomegaly / Q000209:etiology / Q000473:pathology / Q000503:physiopathology / Q000517:prevention & control*; D002908:Chronic Disease; D004195:Disease Models, Animal; D004656:Enalapril / Q000494:pharmacology* / Q000627:therapeutic use; D006339:Heart Rate / Q000187:drug effects; D007668:Kidney / Q000294:innervation*; D008168:Lung / Q000294:innervation*; D008297:Male; D009203:Myocardial Infarction / Q000150:complications / Q000188:drug therapy* / Q000473:pathology / Q000503:physiopathology; D009318:Natriuresis / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D012018:Reflex / Q000187:drug effects*; D013564:Sympathetic Nervous System / Q000187:drug effects* / Q000503:physiopathology; D014554:Urination / Q000187:drug effects; D014882:Water-Electrolyte Balance / Q000187:drug effects
D000806:Angiotensin-Converting Enzyme Inhibitors; D004656:Enalapril