1. Which of the following actions of epinephrine would be antagonized by prazosin but not by propranolol?
(A) Increase in heart rate
(C) Release of renin
(D) Bronchiolar dilation
2. Which of the following adrenoceptor antagonists will reduce responses mediated by both a- and preceptors?
(C) Phenoxybenzamine (d) Labetalol
3. This question is based on the information provided in the accompanying diagram. Shown is the effect of applying norepinephrine on the arterial pressure of an isolated (in vitro) segment of artery from an experimental animal before and after adding drug X to the tissue. Drug X is present during the second application of norepinephrine. Drug X is most likely:
5. This question refers to the accompanying graphs. Shown are dose-response curves for isoproterenol (control) both alone and in the presence of one or the other of two ß-receptor antagonists, drugs X and Y. The responses being measured are an increase in heart rate of a human subject and relaxation of an in vitro strip of human bronchiolar smooth muscle. Drug X is most likely:
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