Receptor 8-adrenergic

E. G protein-conpled receptors /3-Adrenergic receptor kinase (BARK) Rhodopsin kinase II. Ser/Thr/Tyr protein kinases MAP kinase kinase (MAPK kinase) —TEY— phosphorylation by... 

TABLE 23-3 Examples of proteins regulated by phosphorylation Enzymes involved in neurotransmitter biosynthesis Tyrosine hydroxylase Tryptophan hydroxylase Neurotransmitter receptors Adrenergic receptors Dopamine receptors Opioid receptors Glutamate receptors Many others... 

Apart from receptors, adrenergic neu-rotransmission involves mechanisms for the active re-uptake and re-storage... 

G-Protein coupled receptors Adrenergic fS2 receptor (4) Antagonist Agonist... 

Distribution of receptors Adrenergically innervated organs and tissues tend to have a predominance of one type of receptor. For example, tissues such as the vasculature to skeletal muscle have both a and p2 receptors, but the p2 receptors predominate. Other tissues may have one type of receptor exclusively, with practically no significant numbers of other types of adrenergic receptors. For example, the heart contains predominantly Pi receptors. 

Adrenergic blockers inactive receptors by promoting the reuptake of the transmitter back to the neuron and degrading transmitters by enzymes, making the transmitters unable to attach to a receptor. Adrenergic blockers also diffuse transmitters away from receptors. 

Catecholamines and serotonin regulate physiological events at the cellular level by interaction with families of cell-surface receptors. Adrenergic receptors, classified as tti (subtypes aia,b,d)) 2 (subtypes pi, p2> and p3 subcate-... 

Biogenic amine receptors (adrenergic, serotonin, dopamine, muscarinic, histamine)... 

Time scale seconds Examples muscarinic receptors adrenergic receptors... 

In other instances such apparent hybrid activities could be missing or less prominent, as shows the example of epibatidine, a powerful alkaloid from the skin of several arrow poison frogs. Synthetic (+)- and natural (-)-epibatidine have potent agonist activity at ganglionic-type nicotinic receptors. The epibatidines have little or no activity at a variety of other central receptors, including opioid receptors, muscarinic receptors, adrenergic receptors, dopamine receptors, serotonin receptors, and GABA receptors [81]. 

The family of receptors that responds to norepinephrine and related compounds are called adrenergic receptors. Adrenergic receptors in the peripheral nervous system are important in the activity of smooth muscle and cardiac muscle and in metabolism. The effect on most smooth muscle is relaxation, whereas the effect on cardiac muscle is to increase the force and rate of contraction. Drugs that mimic the action of norepinephrine are... 

After activation, protein kinase C phosphorylates specific serine and threonine residues in target proteins. As with cAMP-stimulated protein kinase, the specific cellular responses to protein kinase C activation depend on the ensemble of target proteins that become phosphorylated in a given cell. Known target proteins include calmodulin, the insulin receptor, / -adrenergic receptor, glucose transporter, HMG-CoA reductase, cytochrome P-450, and tyrosine hydroxylase. 

Table 13.1 Major veterinary therapeutic uses of the a2-receptor adrenergic agonists.

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