General Adrenergic Receptors Flashcards
Which type of adrenergic receptor is a G-alpha-q receptor?
Alpha 1
What kind of signal is sent by the alpha-1 g-alpha-q receptor?
An excitatory signal to the blood vessels.
What second messengers are activated by the g-alpha-q receptor and what does this result in?
Phospholipase C (PLC) is activated which hydrolyzes phosphoinositol (PIP2) into IP3 and DAG. IP3 causes an increased release of intracellular calcium and DAG activates protein kinase C which causes the phosphorylation of proteins causing them to be activated.
What type of a physiologic response results from activation of the alpha-1 g-alpha-q receptor?
Smooth muscle constriction.
Which type of adrenergic receptor is a g-alpha-i receptor?
Alpha-2
What kind of signal is sent by the alpha-2 g-alpha-ireceptor?
Inhibitory.
To which three places do the alpha-2 q-alpha-i receptors send inhibitory signals?
- Brain
- Blood vessel
- Pre-synaptic on the post ganglionic neuron innervating the blood vessels.
What second messengers are inactivated by the alpha-2 g-alpha-i receptors?
Adenylate cyclase is inactivated so ATP cannot be converted into cAMP. So we have a decrease in cAMP and potassium conductance is increased.
What type of physiologic responses result from activation of the alpha 2 g-alpha-i receptor?
Smooth vessels constrict (cAMP is responsible for smooth muscle relaxation). Potassium conductance is increased and the cell is hyperpolarized.
What types of adrenergic receptors are g-alpha-s receptor?
Beta 1, 2 & 3.
What kind of signal is sent by the beta 1, 2 & 3 g-alpha-s receptors?
It could be excitatory or inhibitory depending on cAMP actions.
What second messenger is activated by the beta 1, 2 & 3 g-alpha-s receptors?
The activation of adenylate cyclase is responsible for converting ATP into cAMP.
What types of physiologic responses result from the activation of beta 1, 2 & 3 g-alpha-s receptors?
The increase in cAMP relaxes smooth muscle, increases the force of contraction of the heart and increases the rate.
