INTROANSvF_Bb_Arnot

8a signal transduction at alpha 2 adrenergic

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Unformatted text preview: l Transduction at Alpha 2 Adrenergic Receptors Germann and Stanfield Figure 12.8b Alpha Adrenergic Receptors 1 Adr R Gq PLC Ca++ • Depolarization (excitation) • Phenylephrine as selective Ag • Prazosin as selective ANT 2 Adr R Gi AC • • • • decrease cAMP Hyperpolarization (inhibitory) Clonidine as selective Ag Rauwolscine as selective ANT Pre- and post- synaptic Affinities of the Adrenergic Receptors Receptor 1 2 Relative Affinity EPI ≥ NE> IPE EPI ≥ NE > IPE 1 2 3 IPE > EPI = NE IPE > Epi>>NE IPE = NE > Epi Beta Adrenergic Receptors 1 Adr R Gs AC • • • • PKA (LTCC) Usually excitatory NE = EPI affinity Dobutamine as Ag Metoprolol as ANT 2 Adr R Gs AC • • • • cAMP cAMP Usually inhibitory EPI>> NE affinity Terbutaline/Salbuterol as Ag ICI11855 as ANT PKA Signal Transduction at Beta Adrenergic Receptors Germann and Stanfield Figure 12.8b Summary Germann and Stanfield Figure 12.7 IV. A/B. 4. Physiology - EPI> NE EPI> NE Table 11.2 Kalant et al. NE> EPI Germann and Stanfield Table 12.1 & 1 IV.4.A. Parasympathetic m1 m • Ganglia • Gastric & salivary glands • Auto- & Hetero- receptor m m2 • Heart • Smooth muscle (sm) • Autonomic nerve terminal m3 • Sm • Gastric & salivary glands smooth muscle • Low level expression • Cerebral artery vsm IV.4.B. Sympathetic 1 • Vascular smooth muscle (sm) • Genitourinary (GU) sm • Liver • GI sm • Heart 2 • • • • Pancreatic islet cells Platelets Nerve terminals Vascular sm (vsm) 1 • Kidney (JG cells) • Heart 2 • Smc: vascular, bronchial, GI, GU • Skeletal muscle • Liver 3 • adipose SYMPATHETIC ACTIONS increase • HEART RATE • HEART BEAT STRENGTH • BLOOD FLOW TO SKELETAL MUSCLE • BRONCHIOLE DIAMETER • BLOOD FLOW TO INTESTINE • BLOOD GLUCOSE • INTESTINAL ACTIVITY • PUPIL DIAMETER • SWEAT GLANDS increase increase increase decrease increase decrease increase decrease A word about blood vessels and respiratory airways: • If the smooth muscles surrounding these vessels are EXCITED (+ 1 receptors act via IP3), they contract and blood flow or air flow is DECREASED • If the smooth muscles surrounding these vessels are INHIBITED (+ 2 receptors act via cAMP), they relax and blood flow or air flow is INCREASED Receptors in the PNS • Pre-synaptic terminals of parasympathetic choline...
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