Antidiuretic activity

Peptide Biological Antidiuretic activity. . . a activities Vasopressor activity A/P ratio Reference... 

Qrnipressin has almost no antidiuretic activity but it is a potent vasoconstrictor and has been used to limit bleeding during surgery. 

Antidiuretic activity. After ingesting the aerial parts, a 55-year-old man developed urinary retention that required catheterization for relieP b... 

Ornipressin is a selective agonist at vasopressin Vi receptors and has weaker antidiuretic activity than the native hormone. 

CMC did not enhance the ability of desmopressin to concentrate the urine, as measured by urine osmolality or volume response (Table 11). There was also no evidence of any acute effect of the combination of CMC and desmopressin on urinary electrolyte or creatinine concentration (Table 11). The intranasal administration of histamine immediately prior to desmopressin increased the antidiuretic response to desmopressin. Compared to vehicle treatment, urine flow rate response was depressed for a longer duration in response to histamine and desmopressin than after desmopressin alone (Table II). Also it was observed that only histamine and desmopressin in combination, significantly lowered (p < 0.05) cumulative 24 hour urine volume compared to vehicle. As a measure of acute antidiuretic activity, dosing with histamine immediately prior to... 

Eisen, V. D., and Lewis, A. A. G., Antidiuretic activity of human urine after surgical operation. Lancet ii, 361-364 (1954). 

A dose of 1 pg desmopressin acetate has antidiuretic activity that is equivalent to 4U arginine vasopressin. Desmopressin acetate has recently been evaluated in normal horses. The author and coworkers diluted desmopressin acetate (0.1 mg/ml) nasal spray in sterile water and administered 0.05pg/kg i.v. (25 pg, equivalent to 100 U of antidiuretic activity in a 500 kg horse) to horses with polyuria induced by repeated nasogastric intubation of water for 3 days. Urine was collected for 8h after desmopressin acetate administration and there was an increase in urine specific gravity to >1.020 from 2 to 7h after administration (Fig. 10.2). The drug had no effects on heart rate or systemic blood pressure. These preliminary data demonstrate that the i.v. administration of desmopressin acetate appears to be safe and a useful tool for the evaluation of horses with DI. 

Felypressin. Felypressin. 2-L-phenylalunine-il-t.-lysine vasopressin, has relatively low antidiuretic activity and little oxytocic activity. It has considerable pressor (i.c., vasoconstrictor) activity, which differs from that of epinephrine (i.e., following capillary con.striclion in the intestine it lowers the pressure in the vena portae, whereas epinephrine rai.ses the portal pre.ssiire). Felypressin al.so cau.ses increased renal blood flow in the cal. whereas epinephrine brings about a fall In renal bltxal How. Felypressin is 5 time.s more effective as a va.sopre.ssor than is lysine vasopressin and is recommended in surgery to minimi/.e blood How, especially in obstetrics and gynecology. 

Deletion of the free alpha amino group from the Cys in position 1 to form 1-deamino-oxytocin enhanced both the oxytoticand antidiuretic activities (171). Replacement of the sulfur in Cys with a methylene group to form [l-carba]OT resulted in an increase in potency (172) (Table 2.14). 

S X rd 0 IV/IM/nasal. Short half-life (3-5 min.). Potential for uterine tetany or rupture, trauma to infant, post -delivery uterine atony. Prolonged infusion (>24h) may cause water intoxication (antidiuretic activity). Potentiates hypertensive effects of other drugs. May cause stroke/hemorrhage, fetal distress. Synthetic oxytocin mimics the effects of endogenous oxytocin which is released from the hypothalamus. 

Vasopressin (VP), antidiuretic hormone, ADH, H-Cys-Tyr-Phe-Gln-Asn-Cys-Xaa-Gly-NH2 (disulfide bond Cys -Cys ), a member of the neurohypophyseal peptide hormones. VP has antidiuretic activity, and in higher doses it increases blood pressure. In bovine and other mammalian hormones Xaa = Arg (AVP), but in the porcine peptide Xaa = Lys (LVP). VP shows strong structural similarities to oxytocin, and has a slight oijytocin effect. VP is synthesized by the magnoceUular... 

In a subsequent investigation by Heller and Zaimir (1949), oxytocin concentrations in the posterior lobe of the human pituitary gland were assayed on the same samples as those employed by the authors for determination of antidiuretic activities. The variation in the hormone level with age showed great similarity with that recorded for the antidiuretic hormone. The mean oxytocin content observed per milligram of dry tissue was 150 milliunits for newborn children (N = 15) and 754 milliunits for adults (N = 12). Values of 950 and 1050 milliunits were found for samples obtained from 2 adolescent children. The observed increase in the pituitary oxytocin potency during maturation is in agreement with. Tores and Zschim-mer s conclusions. 

Dimerization of the oxytocin molecule by incubation in NaHC03 at pH 8.3 at room temperature yields a biologically inactive compound. When vasopressin is incubated with cysteine or glutathione, the reduction of the disulfide bridge diminishes antidiuretic activity to one-third of its original value. The substitution of the 8-lysine of vasopressin by 1-deamino lysine enhances the antidiuretic activity, but substitution of the 8-lysine by 1-acetyllysine abolishes most of the hormonal activity. 

U-7720 is almost completely inactive because the active metabolite U-20,388 is not formed in this species [273]. U-20,388 administration, however, produces an appreciable hypotensive effect in man, too. One disadvantage of U-20,388 seems to be its antidiuretic activity [84]. 

Position 8. Variations in position 8 of the vasopressins are found in nature in this respect, there are analogies with the oxytocin series. Lysine-vasopressin occurs in the pig, the hippopotamus and the peccary. Introduction of leucine yields oxypressin (Leu -vasopressin = Phe -oxytocin) which has activities intermediate between oxytocin and vasopressin. Introduction of D-amino acids yields compounds with low pressor activity but high antidiuretic activity. 

N-terminal amino-group. Suppression of the N-terminal amino-group enhances oxytocin-like activities and antidiuretic activities but decreases pressor activities. The antidiuretic activity of de-amino -arginine-vasopressin is 3 times higher than the natural hormone. 

---