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Stack #358040
Question | Answer |
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The extent of desensitization of receptors is dependent on __________________ | the intrinsic activity of the agonist (i.e. partial agonists cause much less receptor desensitization. |
G-alpha-s receptor subunit activates _____________ | adenyl cyclase; leading to increased cyclic AMP levels. |
Increased cyclic AMP levels and increased calcium do what to the heart? | Stimulates it; causes increased HR and contractility. |
What type of levels of cAMP lead to contraction of smooth muscle? | Decreased levels of cAMP. |
G-alpha-q receptor subtype activates __________ causing increased levels of _______ to be made | Phospholipase-C-beta enzymes; Ca++ |
Increased PLC levels and Ca levels do what to smooth muscle? And which subunit is this mediated by? | Causes contraction. G-alpha-q. |
G-alpha-i inhibits what? And which receptor subtype's action is this opposing? | Adenyl cyclase; Subtype G-alpha-s. |
Inhibiting adenyl cyclase action leads to decreased __________ levels? And which muscle does this cause contraction in? | cAMP levels; smooth muscle. |
G-beta-gamma subtype activates _____ channels through release from G__/__ | K+, i/o . |
Activation of K+ channels causes ___________ and stops what from being released? | Hyperpolarization; neurotransmitter. |
Along with activating K+ channels, what does G-beta-gamma activate? | GPCR kinases (i.e. beta-adrenergic receptor kinase, Beta-ARK). |
What does phosphorylating GPCR's do? | Causes receptors to be de-sensitized |
Which G protein goes with alpha-1 receptors? | Gq |
Which G protein goes with alpha-2 receptors? | Gi |
Which G protein goes with B receptors? | Gs |
Which effector enzyme goes with alpha-1 receptor and G protein Gq? | +phospholipase C |
Alpha-2 receptor has which G protein? And which effector enzyme? | G protein Gi; and -adenyl cyclase. |
Beta-receptor has which G protein? And which effector enzyme? | G protein s; Effector enzyme +adenyl cyclase. |
Beta receptors and Gs subunit has what effects when they are stimulated? | 1. Activates adenyl cyclase which leads to increased cAMP levels; this leads to increased Ca+ in the heart (and increased contractility) |
Which two receptors affect adenyl cyclase levels (either increasing or decreasing)? | Receptor alpha-2 and the beta receptors |
Which receptor does not affect adenyl cyclase levels but affects Ca and PLC enzymes? | Alpha-1 receptor. |
What are indirect agonists? | Drugs that cause an unregulated release of a transmitter (an endogenous transmitter) |
What are the two ways that indirect agonists work? | 1. By competing with NE for reuptake into the nerve terminal and uptake into vesicles. 2. Also, displace NE from the vesicles and nerve terminal, causing a build up in the nerve synapse. |
How do mixed-function agonists work? | They work directly as agonists on receptors; as well as by both indirect effects (displacing and releasing NE). |
What are tocolytic agents? And what class are they from? | Drugs used to inhibit uterine contractions in premature labor; Beta-agonist. |
G protein 'Gq' is used with which receptor? | Receptor alpha-1. |
G protein 'Gi' is used with which receptor? | Receptor alpha-2. |
G protein 'Gs' is used with which receptors? | The Beta receptors. |
Alpha-1 (G-alpha-q) affect which tissues and organs? | Major blood vessels (excepting skeletal and hepatic), eye, GI sphincters, Bladder sphincters, and liver. |
What effect does alpha-1 (G-alpha-q) have on the eye? | Causes mydriasis (pupil dilation), by contracting the radial muscles. |
Alpha-1 (G-alpha-q) subtype affects GI sphincters how? |