Key result
Insulin elicited a positive inotropic effect on isolated mammalian cardiac muscle, increasing tension to about 120% of control, but significantly impaired the inotropic action of norepinephrine.
Why the study?
Does insulin affect contractile activity and responsiveness to norepinephrine in isolated mammalian cardiac muscle?
Population
Isolated cardiac muscle (right ventricular moderator band of piglets and papillary muscle of cats and kittens)
Comparison
Insulin (1 U/ml) added to the bath vs Untreated muscle (control)
Design
Preclinical
Authors
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Insulin's direct inotropic effects and norepinephrine interaction should not yet change practice; leaves open human myocardial relevance.
Does insulin affect contractile activity and responsiveness to norepinephrine in isolated mammalian cardiac muscle?
Insulin exerts a direct positive inotropic effect on mammalian cardiac muscle while impairing its inotropic responsiveness to norepinephrine.
Lee et al. (1976) studied this question. Insulin vs. untreated muscle was evaluated on active isometric tension and maximal rate of tension development. Insulin elicited a positive inotropic effect on isolated mammalian cardiac muscle, increasing tension to about 120% of control, but significantly impaired the inotropic action of norepinephrine.
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