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Vasopressin

Vasopressin is released by the posterior pituitary in response to increased plasma osmolality, water deprivation, hypovolemia, and hypotension. It acts primarily in the renal collecting duct to increase water permeability and concentration of urine. Vasopressin is also a potent vasoconstrictor. Diabetes insipidus is caused by impaired renal conservation of water due to deficient vasopressin secretion or insufficient renal response. Inappropriate ADH secretion can cause hyponatremia and hypo-osmolality. Therapeutic uses of vasopressin include treating bleeding esophageal varices and central diabetes insipidus.

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397 views2 pages

Vasopressin

Vasopressin is released by the posterior pituitary in response to increased plasma osmolality, water deprivation, hypovolemia, and hypotension. It acts primarily in the renal collecting duct to increase water permeability and concentration of urine. Vasopressin is also a potent vasoconstrictor. Diabetes insipidus is caused by impaired renal conservation of water due to deficient vasopressin secretion or insufficient renal response. Inappropriate ADH secretion can cause hyponatremia and hypo-osmolality. Therapeutic uses of vasopressin include treating bleeding esophageal varices and central diabetes insipidus.

Uploaded by

Kim Lompot
Copyright
© Attribution Non-Commercial (BY-NC)
We take content rights seriously. If you suspect this is your content, claim it here.
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VASOPRESSIN TAGLE Vasopressin Body fluid osmolality- controlled by homeostatic mechanism Released by the posterior pituitary during: 1.

Water deprivation 2. Increased plasma osmolality-principal stimulus 3. Hypovolemia/hypotension -acts primarily in the renal collecting duct -inc permeability of cell membrane -Potent vasopressor with potent vasoconstrictor action -Inc plt aggregation Regulation of Vas secretion 1.hyperosmolality -Above 280mosm/kg, 2-3x inc in plasma conc -Allows pt to survive longer periods of water deprivation. 2. hepatic portal osmoreceptors 3. Hypovolemia, hypotension 4. Hormones neurotransmitters Stimulates rel: Ach, aspartate, cck Histamine, dopa, glutamine, neuropeptide y,subs p, intestinal polypeptide,prostaglandin, angiotensin 2 Inhibitor: Atrial Natriuretic Peptide, GABA, opioids 5. Pharmacological agents Basic pharmacological Vasopressin Receptors -V1a -V1b -V2 V1 receptor-effector coupling Immediate responses -Vasoconstriction

-Glycogenolysis -Plt aggregation -Acth release V1 receptor-effector coupling -Degradation of multivesicular bodies -Endocytosis -Phophorylation of proteins -Exocytosis Renal actions of vasopressin Figure chuva Non renal actions -Cv sys -Cns -Bld coag Dse affecting the vaso Diabetes Insipidus -Dse of impaired renal conservation of h20 -Central DI- dec sec of neurohyphysis -Nephrogenic DI-insufficient renal resp to vasopressin -S/s Polyuria-more than 30/ml/kg/day Dilute urine- less than 200 mosm/kg Polydipsia Fluid deprivation test Desmopressin-will differentiate central from nephrogenic DI Inappropriate ADH -Dse of impaired h20 excretion with accompanying hyponatremia and hypoosmolality -Lethargy, anorexia, n/v, muscle cramps, coma, convulsions, death -Malignancies (oat cell ca), pulmo dse cns injuries, gen surgery -Dilutional hyponatremia -fluoxetine, haloperidol, TCA -Sulfonylureas -Vinca alkaloids -Tx: for symptomatic pts Lithium Tetracycline

Therapeutic Uses -Pitressin -Desmopressin -Lypressin (diapid)-intranasally -Terlipressin (glypressin) bleeding esophageal varices Toxicity: -Mostly d/t v1 receptors acting on vascular and smooth muscle -Less common in desmopressin -Marked facial pallor -Inc GI act nausea, belching -Caution in cad arrhythmias, dec cardiac output Adverse effect -H20 intoxication -Potentiated by carbamazepine chlorpropramide, morphine, TCA and NSAIDS -Dec by lithium, demeclocylcine, ethanol Future directions: Conivaptin (vaprisol) -V2 recptor antagonist -Recently approved by fda for tx of euvolemic hyponatremia in hospitalized pts w/o chf -Pts with SIADH, hypothyroidism, adrenal insufficiency

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