Vasopressin diuretics

Vasopressin is suppHed as Pitressin Taimate (Parke-Davis) for use as an antidiuretic agent adrninistered intramuscularly (see Diuretic agents). 

Atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), and C-type natriuretic peptide (CNP) are members of a family of so-called natriuretic peptides, synthesized predominantly in the cardiac atrium, ventricle, and vascular endothelial cells, respectively (G13, Y2). ANP is a 28-amino-acid polypeptide hormone released into the circulation in response to atrial stretch (L3). ANP acts (Fig. 8) on the kidney to increase sodium excretion and glomerular filtration rate (GFR), to antagonize renal vasoconstriction, and to inhibit renin secretion (Ml). In the cardiovascular system, ANP antagonizes vasoconstriction and shifts fluid from the intravascular to the interstitial compartment (G14). In the adrenal cortex, ANP is a powerful inhibitor of aldosterone synthesis (E6, N3). At the hypothalamic level, ANP inhibits vasopressin secretion (S3). It has been shown that some of the effects of ANP are mediated via a newly discovered hormone, called adreno-medullin, controlling fluid and electrolyte homeostasis (S8). The diuretic and blood pressure-lowering effect of ANP may be partially due to adrenomedullin (V5). 

The mechanism of action of this kappa mediated neuroprotective effect is under investigation. In addition to the diuretic effects mentioned above, it has been shown that CI-977 (11) is inactive in a model of focal brain ischaemia in Brattleboro rats which lack vasopressin and do not exhibit kappa-mediated water diureses [33c]. An alternative mechanism for which there is increasing evidence is an inhibition of excitatory amino-acid release. U-50488 (5) and PD 117302 (12) have been shown to block convulsions in-... 

VLc. Diabetes Insipidus and Vasopressin (Anti-diuretic Hormone)... 

Deficiency of pituitary vasopressin (arginine vasopressin or AVP, also termed anti-diuretic hormone, ADH) causes the syndrome of polyuria, thirst and polydipsia termed cranial diabetes insipidus. It is... 

Nephrogenic diabetes insipidus is due to resistance to action of vasopressin, and therefore DDAVP is not indicated, but some benefit may be gained by using thiazide diuretics or chlorpropamide. The syndrome of inappropriate antidiuretic hormone (SIADH) can be treated by using the antibiotic derivative demeclocycline to induce a state of vasopressin resistance and partial nephrogenic diabetes insipidus. 

Also known as water diabetes, diabetes insipidus (DI) is a rare chronic disease that causes excessive urination. If not properly treated, it can result in electrolyte imbalance and dehydration. It may be caused by a number of factors, including lithium use (a psychiatric drug used for bipolar disorder), neurological disease, or an inadequate amount of ADH (anti-diuretic hormone, or vasopressin, which is produced by the pituitary gland). DI caused by insufficient ADH is called central diabetes insipidus. 

Vasopressin (anti diuretic hormone, ADH) plays an important role in the long-term control of blood pressure through its action on the kidney to increase water reabsorption. This and other aspects of the physiology of vasopressin are discussed in Chapter 15 Diuretic Agents and Chapter 37 Hypothalamic Pituitary Hormones and will not be reviewed here. 

Before the introduction of specific vasopressin receptor antagonists, pharmacological treatments for hyponatremia centered on the use of loop diuretics and nonspecific inhibitors of vasopressin signaling, such as lithium carbonate and demeclocycline.11 The utility of such therapies has been limited by a range of sideeffects. Loop diuretic use can result in electrolyte imbalances and suffers from poor response predictability.11 Lithium carbonate suffers from a low therapeutic index and a risk of renal damage as well as limited effectiveness in many patients. Lithium carbonate has therefore been nearly completely supplanted by demeclocycline, a tetracycline antibiotic, in the treatment of chronic hyponatremia.12 Demeclocycline use is itself limited by its nephrotoxicity (particularly in cirrhotic patients), ability to cause reversible uremia, and ability to induce photosensitivity.1,11... 

The ANF hormones, which derive from higher-molecular-weigth precursors (atriopeptigens), have diuretic properties, i.e. an administration of ANF in the rat increases diuresis and natriuresis (the release of Arg-vasopressin is inhibited) and at the same time the vessels are dilated, apparently by inhibition of catecholamines and angiotensin II. In addition, it has been shown that under volume loading the ANF peptides are released from the atria and develop their effects as hormones in renal, vascular, and other tissues. They can be considered as functional antagonists of the renin-angiotensin system. 

There are two types of disturbances in vasopressin secretion. In central diabetes insipidus, vasopressin secretion is reduced it can be treated by giving vasopressin or desmopressin, which has a longer half-life, by mouth or intranasally. In nephrogenic diabetes insipidus, the plasma vasopressin concentration may be normal but the kidney fails to respond. The latter type of diabetes insipidus does not respond to vasopressin therapy but, paradoxically, can be managed by giving a thiazide diuretic, for example chlortalidone, at a maintenance dose of 50 mg daily. 

Anti-diuretic hormone (arginine vasopressin) is a nine-amino-acid peptide secreted from the posterior pituitary. Within hypothalamic neurons, the hormone is packaged in secretory vesicles together with a carrier protein called neurophysin both are released upon secretion. 

D. Vasopressin has an antidiuretic action. Neither acts as a diuretic. 

Another important urinary regulatory mechanism involves the effects of vasopressin (AVP) also known as anti diuretic hormone (ADH). A decrease in blood pressure or an elevation in plasma osmolality will result in the release of ADH from the posterior... 

As mentioned earlier, cyclic AMP has been postulated as the cellular intermediate in the anti-diuretic action of vasopressin jS9jSo Isolated... 

S43, Vasopressin, Anti diuretic hormone beta-hypo-phamine /3-hypophamine Leiomnone Pitressin Tonephm Vasophysin. The water-soluble pressor principle prepd by synthesis or obtained from the posterior lobe of the pituitary of healthy domestic animals used for food by man V.S.P. XVIII, 770. Separation from oxytocin Kamm el at., J. Am. 

Chlorpromazine may have weak diuretic effects because of a depressant action on the secretion of vasopressin (antidiuretic hormone, ADH), inhibition of reabsorption of water and electrolytes by a direct action on the renal tubule, or both. The syndrome of idiopathic polydipsia and hyponatremia sometimes associated with psychotic illness has respotuled to clozapine, presumably via... 

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