Transcript Antidiuretic Hormone (ADH)/ Vasopressin

Antidiuretic Hormone (ADH)/
Vasopressin
Cell Communication
By: Alejandra Ospina, Megan Campbell
General Information `
Controls body water and solute concentration
 The function of several hormones act on the kidneys
and vascular system
 Also known as Arganine Vasopressin
 Produced by neurosecretory cells in the hypothalamus
 Regulated by osmotic and volume stimuli
 Water deprivation increases osmolality of plasma which
activates hypothalmic osmoreceptors to stimulate ADH
release
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Gland
Secreted from the posterior pituitary gland
 The hypothalamus sends signals to the pituitary
gland to secrete the hormone.
 Once hormone is secreted it goes to the kidney
to put its purpose into effect.
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Base & Structure
9 amino acid structure sequence
 Peptide based hormone
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◦ Hydrophilic – will not go into the cell
◦ Binds with the receptor on the cell’s surface
◦ Six of the amino acids form a ring structure,
joined by disulfide bonds.
Pathway & Messenger
Vasopressin is released and binds to cell membrane at
receptor
 Binding results in ATP breaking down to cAMP
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◦ cAMP is the second messenger
◦ cAMP activates PKA which synthesizes aquaporin
◦ Aquaporins bind in the membrane and let H20 into the cell
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Does not directly communicate with nucleus
Indirectly communicates with cytoplasm and cell
membrane.
Pathway continued…
The receptor is linked to adenylyl cyclase (AC)
enzymes via heterotrimeric G proteins in the membrane;
thus, AC is activated as a consequence of VP binding to its
V2 receptor resulting in the formation of the second
messenger cyclic AMP. Subsequent phosphorylation of
protein kinase A is associated with the final step of water
reabsorption. Cyclic AMP is rapidly degraded to 5*-AMP
by intracellular phosphodiesterase enzymes.
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Pathway
Diagra
m
VPvasopressin
AQPaquaporin
PKA- protein
kinase A
Cellular Response
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Once cAMP is rapidly degraded by intracellular
enzymes, thus the insertion of water channels into the
membrane of the target cell, mediates rapid crossmembrane water transport.
There is also an increased movement of aggraphores
towards these membranes.
The response is an increase of water absorption.
Not a transcription factor
It does turn an enzyme (protein kinase A)
There is no conformational change expect the
introduction of more aquaporins into the membrane.
Positive or Negative Feedback?
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Negative Feedback
•Decreased water levels in body
resulting in more ADH productionincreased thirst- will increase the
amount of aquaporins being added
in increased as well (to reabsorb
more water into the kidney)
•Increased water levels result in a
reduced ADH production telling the
kidney to reabsorb less water.
Consequences of Disruption
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When ADH is inhibited, water will not be reabsorbed at the
tubules and the body will produce dilute urine.
Hyponatremia (not enough sodium (salt) in the body fluids outside
the cells.) and hypo-osmolality resulting from inappropriate,
continued secretion of the hormone despite normal or increased
plasma volume, which results in impaired water excretion.
◦ Symptoms: Confusion, disorientation, delirium, generalized muscle
weakness, myoclonus, tremor, asterixis, hyporeflexia, ataxia, dysarthria,
Cheyne-Stokes respiration, pathologic reflexes, generalized seizures,
coma
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Incontinence- involuntary urination: Common in elderly people.
◦ Lack of ADH at night leads to bladder overfilling and thus urination.
Consequences of Disruption Continued…
•Syndrome of inappropriate
antidiuretic hormone
secretion is also known as
SIADH.
•It is a condition where
your body makes too
much antidiuretic
hormone (ADH).
•Increased ADH makes
water remain inside your
body, causing other
chemicals in the blood such
as salt may decrease.
•Organs may not function
properly
Consequences of Disruption Continued…
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Hyperosmolality
Works Cited
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http://www.vivo.colostate.edu/hbooks/pathphys/endocrine/hypopit/
adh.html
http://joe.endocrinology-journals.org/content/159/3/361.full.pdf
http://images.google.com/
http://emedicine.medscape.com/article/246650-overview
www.uic.edu/classes/phyb/phyb402dbh/lecture4.ppt
http://www.drugs.com/cg/syndrome-of-inappropriate-antidiuretichormone-secretion.html