What is the clinical evidence from this study?

Population: Isolated perfused cat coronary arteries. Intervention: Enalapril vs. Captopril. Primary outcome: Inhibition of angiotensin I and II constrictor actions.

What question did this study set out to answer?

To evaluate the direct coronary vascular effects and angiotensin antagonism of enalapril, enalaprilic acid, and captopril.

February 1, 1984Experimental Biology and Medicine

Coronary Vascular Actions of the Converting Enzyme Inhibitor, Enalapril

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Key result

Enalapril markedly antagonized the coronary vasoconstrictor effects of angiotensin II by up to 95% in isolated cat coronary arteries, whereas captopril failed to significantly antagonize it.

Why the study?

Does enalapril inhibit the vasoconstrictor effects of angiotensin I and II in isolated cat coronary arteries compared to captopril?

Key Points

To evaluate the direct coronary vascular effects and angiotensin antagonism of enalapril, enalaprilic acid, and captopril.
Tested the vascular responses of isolated perfused cat coronary arteries exposed to angiotensin I and angiotensin II.
Administered enalapril (25–200 µg/ml), enalaprilic acid (0.5–1.0 µg/ml), or captopril (up to 250 µg/ml) to assess vasoconstrictor inhibition and blockade duration.
Enalapril inhibited angiotensin I constriction by 65% to 80% (25–100 µg/ml) and directly blocked angiotensin II vasoconstriction by 80 ± 5% at 150 µg/ml and 95 ± 4% at 200 µg/ml, with blockade persisting for 60–90 minutes.
Enalaprilic acid blocked the angiotensin II response by 94 ± 5% (0.5–1.0 µg/ml), whereas captopril failed to significantly antagonize angiotensin II at doses up to 250 µg/ml despite blocking angiotensin I.

Structured PICO

Does enalapril inhibit the vasoconstrictor effects of angiotensin I and II in isolated cat coronary arteries compared to captopril?

Population

Isolated perfused cat coronary arteries used to test the coronary vascular actions of enalapril.

Intervention

Enalapril (25 to 200 micrograms/ml) and enalaprilic acid (0.5 to 1.0 microgram/ml)

Comparator

Captopril (up to 250 micrograms/ml)

Outcome

Inhibition of the constrictor actions of angiotensin I and angiotensin IIsurrogate

Enalapril directly antagonizes the coronary vasoconstrictor effects of angiotensin II in a preclinical model, a property not shared by captopril, potentially contributing to its benefits in myocardial ischemia.

Implication

Hypothesis-generating for differential ACEI coronary effects; requires human validation before any practice implications.

Abstract

Enalapril, a potent angiotensin converting enzyme inhibitor, effectively blocked the constrictor actions of angiotensin I in isolated perfused cat coronary arteries. Enalapril, at concentrations of 25 to 100 micrograms/ml, inhibited angiotensin I by 65 to 80%. Moreover, enalapril at 100 to 200 micrograms/ml, markedly antagonized the coronary vasoconstrictor effects of angiotensin II. At 150 micrograms/ml, enalapril blocked the angiotensin II response by 80 +/- 5%, and at 200 micrograms/ml, it was blocked by 95 +/- 4%. Enalaprilic acid at 0.5 to 1.0 microgram/ml also blocked the angiotensin II response by 94 +/- 5%. Captopril, up to 250 micrograms/ml, failed to significantly antagonize angiotensin II, although it readily blocked angiotensin I in this preparation. The duration of this angiotensin II blockade lasted about 60-90 min. This angiotensin II antagonism may help explain the beneficial effects of enalapril in situations such as acute myocardial ischemia.

Discussion

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Cite This Study

Lefer et al. (1984) studied Isolated perfused cat coronary arteries. Enalapril vs. Captopril was evaluated on Inhibition of angiotensin I and II constrictor actions. Enalapril markedly antagonized the coronary vasoconstrictor effects of angiotensin II by up to 95% in isolated cat coronary arteries, whereas captopril failed to significantly antagonize it.

synapsesocial.com/papers/6a9a45062b9869bfd24e2215 https://doi.org/10.3181/00379727-175-41790

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Implication

Hypothesis-generating for differential ACEI coronary effects; requires human validation before any practice implications.

Coronary Vascular Actions of the Converting Enzyme Inhibitor, Enalapril

Key Points

Structured PICO

Implication

Abstract

Discussion

Cite This Study

Coronary Vascular Actions of the Converting Enzyme Inhibitor, Enalapril

Key Points

Structured PICO

Implication

Abstract

Discussion

Cite This Study

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