B receptor Characterized by a strong response to isoproterenol. B1 receptor and B>receptor Results in activation of adenylyl cyclase and therefore increased concentration of cAMP within the cell
receptor ◼ Characterized by a strong response to isoproterenol. ◼ 1 receptor and 2 receptor ◼ Results in activation of adenylyl cyclase and therefore increased concentration of cAMP within the cell
Distribution of receptors Vasculature to skeletal muscle have both a1 and B2 receptors,but the B2 receptors predominate.The heart contains predominantly B1 receptors
Distribution of receptors ◼ Vasculature to skeletal muscle have both 1 and 2 receptors, but the 2 receptors predominate. The heart contains predominantly 1 receptors
Desensitization of receptors Prolonged exposure to the catecholamines reduces the responsivity of these receptors
Desensitization of receptors ◼ Prolonged exposure to the catecholamines reduces the responsivity of these receptors
ADRENOCEPTORS C 02 B: 2 Vasoconstriction Inhibition of Tachycardla norepinephrine Vasodllation Increased peripheral release Increased lipolysis Slightly decreased resistance Inhibition of perlpheral resistance Increased myocardial Increased blood pressure insulin release contractility Bronchodilation Mydriasis Increased muscle and liver glycogenolys Increased closure of internal sphincter of Increased release the bladder of glucagon Relaxed uterine smooth muscle Figure 6.6 Major effects mediated by o-and B-adrenoceptors