1. (a) There are two main types of adrenergic receptors: the a- and ß-adrenoceptors. Noradrenaline shows slight selectiv

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1 A There Are Two Main Types Of Adrenergic Receptors The A And Ss Adrenoceptors Noradrenaline Shows Slight Selectiv 1 (104.21 KiB) Viewed 17 times

1. (a) There are two main types of adrenergic receptors: the a- and ß-adrenoceptors. Noradrenaline shows slight selectivity for the a-adrenoceptor, whereas isoprenaline shows selectivity for the ß-adrenoceptor. Adrenaline shows no selectivity and binds equally well to both the a- and ß-adrenoceptors. Suggest an explanation for these differences in selectivity. OH OH OH HO NH₂ HO golf gole HO HO HO Noradrenaline Isoprenaline Adrenaline (4 marks) (b) Isoprenaline undergoes metabolism to give the inactive metabolite shown below. Suggest why this metabolite does not bind to the ß-adrenoceptor. OH MeO. HO inactive metabolite of Isoprenaline (3 marks) (c) R-Salbutamol is an anti-asthmatic agent that acts as an adrenergic agonist. Do you think it is likely to show any selectivity between the a- and ß-adrenoceptors? Explain your answer. OH HOH₂C HO R-Salbutamol (3 marks) Page 2 of 8