Pharmacology Which of the following effects of adrenaline would be blocked by phentolamine but NOT by propranolol ? A Cardiac stimulation B Relaxation of bronchial smooth muscle C Relaxation of the uterus D Contraction of the radial smooth muscle in the iris 💡 Explanation Which of the following effects of adrenaline would be blocked by phentolamine but NOT by propranolol ? ✓ Correct Answer: D. Contraction of the radial smooth muscle in the iris