Key result
Captopril lowers blood pressure without altering myocardial inotropic state.
Why the study?
The effect of captopril on ventricular contractility indices in spontaneously hypertensive rats was investigated to understand its influence on myocardial inotropic condition.
Captopril reduces BP without direct inotropic effects; leaves open translation to human HF or diseased myocardium.
Two groups of SHR were treated with captopril (Squibb): the first group (1 month old)--30 mg/kg i.p. twice daily for 77 days, and the second group (8 months old)--20 mg/kg p.o. twice a day for 23 days. The recording of electrocardiogram (ECG), systolic blood pressure (SBP), diastolic blood pressure (DBP), and some isometric indices of the left-ventricular contractility indicate that in all treated animals the values of most of the parameters are considerably lowered compared to the controls. The ratio between velocity of pressure increase and intraventricular pressure/equal to 50 mmHg--(dP/dt)/ICP50/does not change significantly. It can be concluded that in SHR, captopril practically does not influence the inotropic condition of the myocardium.
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VELKOV et al. (1986) studied Spontaneously hypertensive rats (SHR) (n=36). Captopril vs. Physiological saline (untreated controls) was evaluated on (dP/dt)/ICP50 (ratio between velocity of pressure increase and intraventricular pressure equal to 50 mmHg) (p=>0.05). Captopril significantly reduced blood pressure but did not significantly change the load-independent contractility index (dP/dt)/ICP50, indicating no direct effect on myocardial inotropic state.
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