TYK57
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All of the following are effects of B-agonists except:
A. Inotropy
B. Lusitropy
C. Chronotropy
D. Dromotropy
Answer
The answer is B. Stimulation of the Beta-1 receptors leads to increased force of contraction (inotropy), increased heart rate (chronotropy), and increased speed of impulse conduction along the conduction pathways (dromotropy). Stimulation of the receptors that increase force of contraction impair the ventricular relaxation. As such, these agents may actually impair diastolic function of the heart and make the ventricle less compliant. Drugs known to ENHANCE ventricular relaxation are said to have lusitropic effects.
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