Alpha Adrenergic Receptors concept for NEET/USMLE/FMGE/PLAB скачать в хорошем качестве

Alpha Adrenergic Receptors concept for NEET/USMLE/FMGE/PLAB

Alpha Adrenergic Receptors concept for NEET/USMLE/FMGE/PLAB Alpha receptors are of two types alpha-1 and alpha-2. 1. Alpha-1 receptors are postsynaptic and Gq subtype of GPCRs. Hence in the respective organs of location effect is produced by an increased calcium. E.g. Blood vessels - Vasoconstriction Prostatic urethra - Contraction Bladder sphincter - Contraction Radial muscles of iris - Contraction, which produces mydriasis Skeletal muscles and Liver - Glycogenolysis and Gluconeogenesis which produces hyperglycemia 2. Alpha-2 receptors are predominantly presynaptic and Gi subtype of GPCRs. Thus these are present in presynaptic neurons and hence decrease release of norepinephrine (primary action). Some exceptions are there where alpha-2 receptors are postsynaptic as well. Blood vessels - Alpha-2 are Gq subtype and hence produce vasoconstriction Beta islet cells - Alpha-2 are Gi subtype and hence decrease release of insulin and cause hyperglycemia.