Polycystic ovary syndrome in Salvador, Brazil: a prevalence study in primary healthcare

BACKGROUND

Polycystic ovary syndrome (PCOS) is a common condition in women of reproductive age. It is characterized by hyperandrogenism, oligomenorrhea/amenorrhea and polycystic ovaries. It is associated with obesity, diabetes, dyslipidemia and cardiovascular disease. No studies have been conducted on the prevalence of PCOS in Brazilian or South American women. Few studies using the Rotterdam criteria have been published. The objective of the present study was to calculate the prevalence of PCOS at primary healthcare level in Salvador, Brazil based on these criteria.

METHODS

This was a cross-sectional, two-phase study conducted in a probability sample of women of 18-45 years of age screened for cervical cancer in the primary healthcare network of the city of Salvador, Brazil. In the first phase, interviews were conducted, weight, height, waist circumference, blood pressure and random blood sugar levels were measured, and the presence of acne and hirsutism was investigated. Women with at least one diagnostic criterion were referred for the second phase, which consisted of specialist consultation, pelvic ultrasonography and hormone measurements for differential diagnosis and/or investigation of a second criterion.

RESULTS

Of the 859 women interviewed, 88.5% were black and 58.7% had 11 years of schooling or less. A diagnosis of PCOS was excluded in 84.4%, undetermined in 7.1% and confirmed in 8.5% (95% CI: 6.80-10.56). There were no statistically significant differences between these three groups with respect to weight, body mass index, waist circumference, blood sugar levels or arterial blood pressure. Women with PCOS were younger (p = 0.00), taller (p = 0.04), had fewer children (p = 0.00), were better educated (p = 0.01), and had higher total testosterone levels (p = 0.01) and a higher LH/FSH ratio (p = 0.01).

CONCLUSION

According to the Rotterdam criteria, the prevalence of PCOS in women seeking primary healthcare in Salvador, Brazil, was 8.5%.

Large-scale quantitative LC-MS/MS analysis of detergent-resistant membrane proteins from rat renal collecting duct

In the renal collecting duct, vasopressin controls transport of water and solutes via regulation of membrane transporters such as aquaporin-2 (AQP2) and the epithelial urea transporter UT-A. To discover proteins potentially involved in vasopressin action in rat kidney collecting ducts, we enriched membrane "raft" proteins by harvesting detergent-resistant membranes (DRMs) of the inner medullary collecting duct (IMCD) cells. Proteins were identified and quantified with LC-MS/MS. A total of 814 proteins were identified in the DRM fractions. Of these, 186, including several characteristic raft proteins, were enriched in the DRMs. Immunoblotting confirmed DRM enrichment of representative proteins. Immunofluorescence confocal microscopy of rat IMCDs with antibodies to DRM proteins demonstrated heterogeneity of raft subdomains: MAL2 (apical region), RalA (predominant basolateral labeling), caveolin-2 (punctate labeling distributed throughout the cells), and flotillin-1 (discrete labeling of large intracellular structures). The DRM proteome included GPI-anchored, doubly acylated, singly acylated, cholesterol-binding, and integral membrane proteins (IMPs). The IMPs were, on average, much smaller and more hydrophobic than IMPs identified in non-DRM-enriched IMCD. The content of serine 256-phosphorylated AQP2 was greater in DRM than in non-DRM fractions. Vasopressin did not change the DRM-to-non-DRM ratio of most proteins, whether quantified by tandem mass spectrometry (LC-MS/MS, n=22) or immunoblotting (n=6). However, Rab7 and annexin-2 showed small increases in the DRM fraction in response to vasopressin. In accord with the long-term goal of creating a systems-level analysis of transport regulation, this study has identified a large number of membrane-associated proteins expressed in the IMCD that have potential roles in vasopressin action.

Induction of uPA release in human peripheral blood lymphocytes by [deamino-Cysl,D-Arg8]-vasopressin (dDAVP)

[deamino-Cys(l),d-Arg(8)]-vasopressin (dDAVP), known to be an arginine vasopressin (AVP) V(2) receptor agonist, is an agent that increases fibrinolytic activity levels in plasma after its infusion into the human body. However, mechanisms underlying an increase and exact localization of the extrarenal dDAVP-responsive V(2) receptor remain unclarified. Two AVP receptors, V(1a) and V(2), and a related oxytocin (OT) receptor were found to be expressed in human lymphocytes. Furthermore, we found an increase of fibrinolytic activity in the medium of peripheral lymphocytes obtained from human volunteers less than 20 min after dDAVP infusion. The increased activity was also detected in the medium after incubating the lymphocytes in the presence of dDAVP in vitro, being highest at 20 min after the incubation. In accord with the increased fibrinolytic activity, the levels of urokinase-type plasminogen activator (uPA) in the medium were also increased. However, there was no significant difference of plasminogen activator inhibitor-1 (PAI-1), pro-uPA, and tissue-type plasminogen activator (tPA) concentrations in the medium between dDAVP treatment and control. When lymphocytes were preincubated with a V(2) receptor antagonist [Adamantaneacetyl(1),O-Et-d-Tyr(2),Val(4),Aminobutyryl(6),Arg(8,9)]-vasopressin, the dDAVP-induced uPA increase was diminished. In contrast, preincubation with a V(1) receptor antagonist, [beta-Mercapto-beta,beta-cyclopentamethylenepropionyl(1),O-Me-Tyr(2),Arg(8)]-vasopressin, prior to dDAVP treatment resulted in a greater increase of the uPA concentration in the medium than with the dDAVP treatment alone. Thus it was suggested that dDAVP may induce uPA release from human lymphocytes via V(2) receptor-mediated reaction, and also via cross-talk between V(1) and V(2) receptors.

Design of potent and selective agonists for the human vasopressin V1b receptor based on modifications of [deamino-cys1]arginine vasopressin at position 4

The glutamine(4) residue in [deamino-Cys(1)]arginine vasopressin (dAVP) was replaced by a broad series of aliphatic, aromatic, polar, and charged amino acids to give the following peptides: d[Gly(4)]AVP (1), d[Ala(4)]AVP (2), d[Abu(4)]AVP (3), d[Nva(4)]AVP (4), d[Nle(4)]AVP (5), d[Leu(4)]AVP (6), d[Ile(4)]AVP (7), d[Thi(4)]AVP (8), d[Phe(4)]AVP (9), d[Tyr(4)]AVP (10), d[Trp(4)]AVP (11), d[Asn(4)]AVP (12), d[Ser(4)]AVP (13), d[Thr(4)]AVP (14), d[Dap(4)]AVP (15), d[Dab(4)]AVP (16), d[Orn(4)]AVP (17), d[Lys(4)]AVP (18), d[Arg(4)]AVP (19), d[Har(4)]AVP (20), and d[Glu(4)]AVP (21). All peptides were synthesized by solid-phase methods using BOC chemistry for all but one peptide (8), which required the use of Fmoc chemistry. The binding and functional properties of these position 4 substituted analogues of dAVP (d[X(4)]AVP) and the previously reported d[Cha(4)]AVP (Derick et al. Endocrinology 2002, 143, 4655-4664) were evaluated on human arginine vasopressin (AVP) V(1a), V(1b), and V(2) receptors and on the human oxytocin (OT) receptor expressed in living Chinese hamster ovary (CHO) cells. Binding studies revealed that broad modifications of the fourth residue of dAVP do not significantly alter affinity for the human V(1b) receptor. Only aromatic (Phe, Tyr, Trp) or negatively charged (Glu) residues reduce V(1b) affinity. By contrast, the human V(1a) and more particularly the human V(2) and the OT receptors are more sensitive to many of these modifications. Thus, the replacement of the Gln(4) residue of dAVP by aliphatic (Leu, Cha) or positively charged (Orn, Lys, Arg, Har) amino acids led to analogues exhibiting drastic reductions of their affinity for the human V(1a), V(2), and OT receptors. Consequently, in addition to the previously reported d[Cha(4)]AVP, peptides 6 and 17-20 display excellent selectivities for the human V(1b) receptor. The key structural requirement responsible for optimal V(1b) selectivity appears to be the length and branching of the aliphatic side chain of the fourth residue of dAVP. Functional studies performed on CHO cells expressing the different human AVP/OT receptors confirm the V(1b) selectivity of peptides 6, 17, 18, 20, and d[Cha(4)]AVP. However, d[Arg(4)]AVP (19), which triggers an excellent coupling between the human V(2) receptor and adenylyl cyclase, was found to exhibit both V(1b) and V(2) agonism in functional tests. More interestingly, these functional experiments revealed that, depending on the AVP/OT receptor, a given d[X(4)]AVP analogue may behave as a full agonist or as a partial agonist. This strongly suggests that the fourth residue of dAVP plays an important role in the coupling between the hormone-receptor complex, the heterotrimeric G protein, and the effectors. In conclusion, the synthesis of these d[X(4)]AVP analogues led to the discovery of new V(1b) agonists with high affinity and greatly enhanced selectivities. Thus, in addition to d[Cha(4)]AVP, d[Leu(4)]AVP (6), d[Orn(4)]AVP (17), d[Lys(4)]AVP (18), and d[Har(4)]AVP (20) are useful new tools for studying the structure and the function of the human V(1b) receptor.

Effect of rosiglitazone on spontaneous and clomiphene citrate-induced ovulation in women with polycystic ovary syndrome

OBJECTIVE

In women suffering from polycystic ovary syndrome (PCOS), correction of hyperinsulinemia results enhances spontaneous ovulation or alternatively, the responsiveness to ovulation induction agents such as clomiphene citrate (CC). We investigated the effect of rosiglitazone maleate on ovulation induction in overweight and obese, CC-resistant women with PCOS.

DESIGN

Double-blind, randomized, placebo-controlled trial.

SETTING

Academic reproductive endocrinology clinic.

PATIENT(S)

Overweight and obese women with clinical and laboratory manifestations of PCOS who desired pregnancy and were resistant to CC.

INTERVENTION(S)

Twenty-five women were randomized into two treatment groups. Subjects in Group I (n = 12) were randomized to receive rosiglitazone 4 mg b.i.d. with a placebo on cycle days 5-9. Group II (n = 13) was randomized to receive rosiglitazone 4 mg b.i.d. with CC on cycle days 5-9. The duration of the study was 2 months.

MAIN OUTCOME MEASURE(S)

The primary outcome was ovulation as defined by luteal serum progesterone greater than 5 ng/dL assessed on days 21, 24, and 28 of the cycle. Secondary outcomes were pregnancy and changes in insulin sensitivity, serum lipoproteins, and androgens.

RESULT(S)

Overall, 14 of 25 (56%) women, who were previously resistant to CC, successfully ovulated. In subjects taking rosiglitazone alone (Group I), 4 of 12 (33%) subjects ovulated compared with 10 of 13 (77%) women randomized to rosiglitazone with CC (Group II) (P=.04, Fisher's exact). One subject in Group I became pregnant, resulting in one uncomplicated live birth; two subjects in Group II conceived, with one successful live birth and one first trimester, spontaneous abortion. For all subjects, fasting insulin declined from 29.4 +/- 13.8 microU/mL to 17.3 +/- 7.8 microU/mL after rosiglitazone (P=.003, paired t-test). Although mean levels of total testosterone (T) and dehydroepiandrosterone sulfate (DHEAS) did not decline significantly, sex hormone-binding globulin (SHBG) did increase from 0.7 +/- 0.3 microg/dL to 1.0 +/- 0.3 microg/dL after rosiglitazone therapy (P=.001, paired t test). There was also a decrease in luteinizing hormone (LH) from 9.4 +/- 6.3 mU/mL to 7.2 +/- 3.7 mU/mL (P=.01). Lipoproteins including total cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL), and triglycerides did not change.

CONCLUSIONS

Short-term rosiglitazone therapy enhances both spontaneous and clomiphene-induced ovulation in overweight and obese women with PCOS. Rosiglitazone therapy improves insulin sensitivity and decreases hyperandrogenemia primarily through increases in SHBG.

Conformations and receptor activity of desmopressin analogues, which contain gamma-turn mimetics or a psi[CH(2)O] isostere

Three analogues of the antidiuretic drug desmopressin ([1-desamino,8-D-arginine]vasopressin) have been prepared. In two of these, gamma-turn mimetics based on a morpholin-3-one framework have been inserted instead of residues Phe3-Asn5, whereas the third analogue has a methylene ether isostere in place of the amide bond between residues 3 and 4. The three analogues were used to probe if the structure determined for desmopressin in aqueous solution, which contains an inverse gamma-turn centered around Gln4, is important in interactions with the vasopressin V(2) receptor. Conformational studies revealed that the analogues that contain either an inverse gamma-turn mimetic or a methylene ether isostere mimicked the conformation of desmopressin fairly well and very well, respectively. Despite this, the analogues displayed only very low agonistic activities at the vasopressin V(2) receptor. Consequently, an inverse gamma-turn involving residues Phe3-Asn5 does not appear to be important when desmopressin is bound to the V(2) receptor. In addition, it was concluded that the amide bond between Phe3 and Gln4 in desmopressin is crucial for interactions with the antidiuretic V(2) receptor.

Stereoselective synthesis of Psi[CH(2)O] pseudodipeptides and conformational analysis of a PhePsi[CH(2)O]Ala containing analogue of the drug desmopressin

A method for synthesis of XaaPsi[CH(2)O]Ala/Gly pseudodipeptides in good yields and excellent diastereoselectivity from azido alcohols and (R)-2-chloropropionic acid or tert-butyl bromoacetate has been developed. Insertion of one of the pseudodipeptide building blocks in the peptide drug desmopressin revealed that methylene ether isosteres may have only a minor influence on the secondary structure of peptides.

Changes in plasma arginine vasotocin (AVT) concentration and dorsal aortic blood pressure following AVT injection in the teleost Platichthys flesus

Dorsal aortic blood pressure and plasma arginine vasotocin (AVT) concentrations have been assessed in free swimming, chronically cannulated flounder following AVT injection. Intraarterial AVT at doses of 4.76 x 10(-12) mol.kg-1 and greater caused a biphasic change in blood pressure (an initial fall followed by a sustained pressor response). Doses above 4.76 x 10(-12) mol.kg-1 were associated with plasma AVT concentrations (20 min after injection) 2-3 orders of magnitude greater than the physiological range and must be considered pharmacological. Injection of the lowest pressor AVT dose (4.76 x 10(-12) mol.kg-1), 20 min after injection, increased plasma AVT concentrations to 23.4 +/- 6.1 fmol x ml-1. This increase is close to plasma AVT concentrations recently reported in untreated fish; however, in the initial period after injection plasma levels were calculated to be considerably higher than the physiological range. These results confirm that AVT is pressor in flounder but suggest that the pressor response may occur only at circulating AVT levels above the normal physiological range. The biphasic response to AVT and the differing responses to mammalian V1 and V2 type receptor agonists in the current work suggests that AVT may contribute to regional blood flow distribution in teleosts rather than blood pressure regulation.

A V1-type receptor for mediating the neurohypophysial hormone-induced ACTH release in trout pituitary

We analysed the effects of specific neurohypophysial analogues for pharmacological characterization of the type of vasotocin receptor involved in the control of the adrenocorticotrophin hormone (ACTH) release from the perifused pituitary in the rainbow trout, Oncorhynchus mykiss. Mammalian corticotrophin releasing factor (CRF) and teleostean neurohypophysial peptides (arginine vasotocin (AVT) and isotocin (IT)) stimulated ACTH release. Analysis of concentrations giving half-maximal effects (D50) showed that these peptides affected ACTH release in the following order of potency: CRF (8 x 10(-13) M) > AVT (2 x 10(-10) M) > IT (10(-7) M). Maximal responses (Dmax) were obtained for hormonal concentrations of 10(-10) M, 10(-8) M and 10(-6) M respectively. This suggests that AVT and IT have different roles in the control of ACTH release. The values obtained for AVT and IT were in agreement with the circulating levels we previously found for these peptides. Specific V1 or V2 agonists or antagonists (with reference to vasopressin in mammals) were used to define the specificity of the neurohypophysial peptide receptor involved in this stimulation. The V1 agonist, [Phe2, Orn8]-oxytocin, stimulated ACTH release while the V2 agonist, [deamino1, Val4, D-Arg8]-vasopressin, had no such effect. Maximal and half-maximal responses were obtained in the presence of the V1 agonist with 10(-7) M and 7 x 10(-9) M respectively, and were in the range of values obtained with natural peptides. The V1 antagonist, [d(CH2)5(1), O-Me-Tyr2, Arg8]-vasopressin, and the V2 antagonist, [d(CH2)5(1), D-Ile2, Ile4, Arg8, Ala9]-vasopressin, maximally reversed the 10(-9) M AVT-stimulated ACTH release by 60% and 25% respectively, for a 5 x 10(-10) M concentration of the analogues and a D50 approximately 2 x 10(-11) M. These results demonstrated the presence of only one V1-type receptor in fish pituitary, with some of the structural and functional peculiarities typically displayed by the mammalian V1a-type receptor, but distinct from it. In this sense, the fish pituitary vasotocin receptor may represent a novel type of neurohypophysial hormone receptor, more closely related to the mammalian V1b-type.

Glycosylated peptide hormones: pharmacological properties and conformational studies of analogues of [1-desamino,8-D-arginine]vasopressin

Two analogues of the antidiuretic drug [1-desamino,8-D-arginine]vasopressin (DDAVP), which have a glycosylated serine at position 4, have been prepared by Fmoc solid phase peptide synthesis. The glycosylated analogues had significantly higher bioavailabilities than the nonglycosylated [D-Tyr2,Ser4]DDAVP and DDAVP on intraintestinal administration in rat. The improved bioavailability resulted from an increased absorption from the small intestine and most likely from an increased stability toward enzymatic degradation, whereas plasma clearance was either unaffected or slightly increased by the glycosylation. The glycosylated analogues displayed only very low agonistic and antagonistic activities at the vasopressin V2-receptor. Conformational studies performed by 1H NMR spectroscopy did not reveal any major influence from glycosylation on the conformation of the peptide backbone. The lack of receptor binding displayed by the analogues is therefore most likely explained by steric repulsion between the carbohydrate moiety and the vasopressin receptor which prevents receptor binding.

Agonist and antagonist specificities of decidual prostaglandin-releasing oxytocin receptors and myometrial uterotonic oxytocin receptors in pregnant rats

This paper describes further pharmacological characterization of the decidual prostaglandin-releasing oxytocin receptors and the myometrial uterotonic oxytocin receptors in the uterus of the pregnant rat. The effects of oxytocin, arginine-vasopressin and their related agonists and antagonists on the release of PGF2 alpha were studied in vitro on isolated uteri from rats on day 19-20 of pregnancy that had been incubated in Krebs buffer, pH 7.4, at 37 degrees C. The concentration of PGF2 alpha in the media was measured using specific radioimmunoassays. It was found that the decidual and myometrial oxytocin receptors exhibit different ligand specificities. Of the agonists tested, oxytocin and arginine-vasopressin stimulated PGF2 alpha release in a dose-dependent manner. Arginine-vasopressin has only 3% of the uterotonic potency of oxytocin, but was found to have 16% of its PGF2 alpha-releasing activity. [4-Threonine, 7-glycine]oxytocin, a highly potent and selective uterotonic oxytocin analogue, had no detectable prostaglandin-releasing activity at a dosage 30 times higher than oxytocin. However, 1-deamino-[8-D-arginine]vasopressin, a highly potent and selective antidiuretic arginine-vasopressin analogue, which has only 10% of the uterotonic activity of arginine-vasopressin, was as potent as arginine-vasopressin in prostaglandin-releasing activity.(ABSTRACT TRUNCATED AT 250 WORDS)

In vivo diuretic effect of a new non-peptide arginine vasopressin antagonist, OPC-31260, in conscious rats

The present study was undertaken to determine whether a non-peptide arginine vasopressin (AVP) antagonist (5-dimethylamino-1-[4-(2-methylbenzoylamino)benzoyl]-2,3,4,5-tetra hydro-1H- benzazepine; OPC-31260) antagonizes the antidiuretic action of endogenous and exogenous AVP in conscious rats. OPC-31260, given orally at a dose of 5 mg/kg or higher, increased urinary volume (UV) and reduced urinary osmolality (Uosm) in a dose-dependent manner, in rats acutely denied access to water. Minimal Uosm was obtained 1-2 h after oral administration of OPC-31260. OPC-31260 caused sustained water diuresis for more than 12 h when water was available ad libitum since OPC-31260 (30 mg/kg) reduced Uosm to less than 230 mOsmol/kg H2O, significantly less than the control value of 600 mOsmol/kg H2O. Water deprivation for 24 h increased plasma AVP levels to 7.2 pmol/l and increased Uosm to 2160 mOsmol/kg H2O. In such water-deprived rats, oral administration of OPC-31260 at 100 mg/kg was diuretic; it markedly increased free water clearance and decreased Uosm to 202 mOsmol/kg H2O. In homozygous Brattleboro rats (with inherited AVP deficiency), given free access to water, subcutaneous infusion of the V2 agonist 1-deamino-8-D-AVP (dDAVP) at a rate of 1 ng/h markedly decreased UV to 12.6 from 148.7 ml/day and increased Uosm to 1762 from 231 mOsmol/kg H2O. OPC-31260 (30 mg/kg) promptly increased UV and reduced Uosm to levels similar to those before the administration of dDAVP; repeated OPC-31260 treatment had sustained effects. These results indicate that OPC-31260 is an orally effective non-peptide AVP antagonist to the antidiuretic action of AVP in the conscious rat.

Vasopressin-binding sites in the pig pituitary gland: competition by novel vasopressin antagonists suggests the existence of an unusual receptor subtype in the anterior lobe

Arginine vasopressin (AVP) acts in the pituitary gland, in synergy with corticotrophin-releasing factor, to induce ACTH release in response to stressful stimuli. Pituitary AVP receptors in the rat are coupled to phospholipase C, as are the so-called V1-type AVP receptors. The present study examined [3H]AVP binding in membranes prepared from the anterior lobe of the pituitary gland of the pig. [3H]AVP, alone or in competition with analogues, bound to sites in the pig anterior lobe which are pharmacologically similar to those described previously by others in the rat pituitary gland. For comparison, the same competition studies were performed on membrane preparations from the rat liver which contain the classic V1-type AVP receptor. Pituitary and liver AVP-binding sites were dissimilar; both cyclic and linear V1 antagonists had, in general, a much lower affinity for pituitary AVP-binding sites than for those in the liver. Thus, Phaa-D-Tyr(Et)-Phe-Gln-Asn-Lys-Pro-Arg-NH2 (Phaa = phenylacetyl) has a 2500-fold greater affinity for the latter (negative logarithm of inhibition constant (pKi) = 9.64) than for the former (pKi = 6.22). One linear antagonist, Pa-D-Tyr-Phe-Val-Asn-Arg-Pro-Arg-Arg-NH2 (Pa = propionyl) had about equal affinities for liver and pituitary membranes (pKi = 6.39 and 6.53 respectively). Another compound, Phaa-D-Tyr-Phe-Val-Asn-Arg-Pro-Arg-Arg-NH2 had the highest affinity found to date for binding to AVP sites in the pituitary (pKi = 7.43). These findings suggest some ideas for the design of more potent and/or selective AVP analogues acting in the pituitary gland.

Gastrointestinal absorption and plasma clearance rates of [D-Arg8]vasopressin analogues in the rat

The gastrointestinal absorption of a series of vasopressin (VP) analogues with enhanced enzymatic stability was determined in chronically catheterized, conscious rats. The following peptides were used: [Mpa1,D-Arg8]vasopressin (dDAVP), [Mpa1,Asn4,D-Arg8]VP, [Mpa1,Val4,D-Arg8]VP, [Mpa1,(CH3)3Ala4,D-Arg8]VP, [Mpa1,Tyr(ethyl)2,D-Arg8]VP, and [Mpa1,D-Tyr(ethyl)2,Ile3,Val4,D-Arg8]VP. The peptides were administered by gavage feeding and blood samples were taken repeatedly for 3 h. In another series of experiments, plasma clearance rates (Clp) were determined using the constant infusion method. Plasma concentrations were measured by use of a cross-reacting dDAVP antiserum in a radioimmunoassay method. The bioavailability of all peptides was below 0.1%. The Clp values differed sevenfold; the lowest was for [Mpa1,D-Tyr(ethyl)2,Ile3,Val4,D-Arg8]VP and the highest was for [Mpa1,Asn4,D-Arg8]VP. With the exception of dDAVP the Clp values of the analogues showed an inverse relationship with hydrophilicity. Incubations in relatively concentrated intestinal contents for 1 h showed extensive degradation of the analogues except for [Mpa1,D-Tyr(ethyl)2,Ile3,Val4,D-Arg8]VP. It can be concluded that, in the rat, the bioavailability of dDAVP is lower than in other animal species and in man. Increased resistance to peptide degradation by gastrointestinal contents did not improve absorption. Therefore, the permeability properties of the intestinal mucosa are likely to be a more important factor affecting the gastrointestinal absorption of this group of peptides, although postabsorption events, like hepatic extraction, may also play a role.

Evidence that endogenous arginine-vasopressin (AVP) is involved in the maintenance of the growth and steroidogenic capacity of rat adrenal zona glomerulosa

A 7-day subcutaneous infusion with the AVP antagonist [Deamino-Pen1, Val4, D-Arg8]-vasopressin (AVP-A; 3 nmol.kg-1 x min-1) significantly lowered plasma aldosterone concentration in rats, without affecting the plasma levels of ACTH and corticosterone. Prolonged AVP-A treatment caused a marked atrophy of adrenal zona glomerulosa (ZG) and its parenchymal cells, without inducing any significant change in zona fasciculata morphology. Isolated ZG cells from AVP-A-infused rats evidenced a notable decrease in both their basal and maximally-stimulated aldosterone production. The simultaneous infusion of rats with AVP (3 nmol.kg-1 x min-1) completely reversed all these effects of AVP-A. These findings suggest that endogenous AVP may be specifically involved in the maintenance of the growth and steroidogenic capacity of rat adrenal ZG. Moreover, they seem to indicate that under basal conditions the pituitary-adrenal-glucocorticoid axis is independent of AVP release.

Pharmacokinetics of 1-deamino-8-D-arginine vasopressin after various routes of administration in healthy volunteers

OBJECTIVE

We investigated the pharmacokinetics and biological effects of 1-deamino-8-D-arginine vasopressin (dDAVP) in healthy adults after intravenous, subcutaneous, intranasal, peroral, sublingual and intrarectal administration.

DESIGN

Eight normal volunteers were studied over an 8-hour period after each drug administration, separated by at least one week. For intravenous and subcutaneous administration, the subjects received 2 micrograms of dDAVP. The intranasal and sublingual doses were 20 micrograms and the rectal dose was 50 micrograms. Oral administration of dDAVP was effected with a 200-micrograms tablet.

MEASUREMENTS

Plasma and urinary levels of dDAVP were measured using a specific and sensitive radioimmunoassay.

RESULTS

A significant increase of urine osmolality was observed after all routes of administration, except the sublingual and intrarectal for up to 8 hours after administration. After intravenous administration, the half-life of elimination (t1/2) of dDAVP was 78 +/- 10 minutes. An extensive adsorption of dDAVP to the plastic syringe was found with intravenous but not with subcutaneous administration. Using the area under the curve of dDAVP from the subcutaneous administration as a reference, bioavailability was found to be 3.4% after intranasal administration and 0.1% after oral administration. After sublingual and intrarectal routes of administration no detectable dDAVP was found in the blood; however, low amounts were found in the total 24-hour urine.

CONCLUSION

The bioavailability of dDAVP seems lower than previously reported after intranasal and oral administration.

Tissue plasminogen activator enhancing activity of vasopressin analogues in monkeys: structure-activity study

Marmocets were used in a structure activity study of the ability of vasopressin analogues to activate plasminogen activator (tPA). In evaluation of dDAVP analogues with L-alanine migrating from position 2 to 9 we found [L-Ala4]dDAVP and [L-Ala5]dDAVP to be potent activators of tPA. Double substitutions in dDAVP showed that combinations of a modification in position 4 valine with a change at position 2 (2-O-methyltyrosine) generated tPA releasing activity. On the other hand enlargement of the substituent at position 2 (2-O-ethyltyrosine) completely eliminated the activity of [L-Val4]dDAVP. The tPA activity is dependent on the position of a positively charged group at the amino acid in position 8 of the peptide chain. A shift of the guanido group further away from the backbone (D-arginine to D-homoarginine) resulted in a loss of tPA activating properties.

Differential effects of V2 vasopressin agonist and antagonists on blood pressure regulation in normotensive (WKY) and spontaneously hypertensive (SHR) rats

The effects of arginine vasopressin analogs with V2 agonistic and antagonistic properties on blood pressure (BP) and heart rate (HR) were compared in conscious, spontaneously hypertensive (SHR) and normotensive (WKY) rats under resting conditions and after administration of phenylephrine (Phe) and sodium nitroprusside (SN). In WKY rats, resting BP and HR were not significantly affected during intravenous (i.v.) infusion of dVDAVP, (V2 agonist; 200 pg/kg/min), d(CH2)5 (D-Ile2,Abu4]AVP (V2 antagonist 1; weak V1 antagonist; V2/V1 ratio = 29; 0.6 microgram/kg/min), d(CH2)5[D-Ile2,Ile4,AlaNH2]AVP (V2 antagonist 2; very weak V1 antagonist; V2/V1 ratio = 83; 0.6 microgram/kg/min) and combined infusion of V2 agonist and V2 antagonist 2. Under resting conditions BP and HR were not affected in WKY by any of the treatments. In SHR rats BP and HR were significantly decreased by V2 antagonist 2 infused alone or in combination with V2 agonist. In WKY but not in SHR V2 agonist without and with prior V2 receptors blockade significantly augmented bradycardia associated with a maximum increase of the systolic blood pressure after Phe administration. Significant differences were found between SHR and WKY in SN-induced changes of HR and BP after administration of V2 agonist and antagonists. The results suggest that circulating vasopressin may modify the baroreflex by interaction with receptors which are stimulated by V2 agonist but are different from the classical V2 receptors. The study supports evidence for differential effects of vasopressin analogs on blood pressure and blood pressure-heart rate relations in WKY and SHR.

Vasopressin-induced antipyresis in the medial amygdaloid nucleus of conscious rats

Experiments were undertaken to characterize a possible receptor mediating antipyretic action of arginine vasopressin (AVP) within the medial amygdaloid nucleus (meA) in the conscious rat. Additional experiments were directed at determining whether the action of endogenously released AVP can be revealed in the meA during fever in the conscious rat. These objectives were achieved using vasopressin analogues directed against vasopressor (V1a) and antidiuretic (V2) receptors. Bilateral injection of AVP (40 pmol) into the meA of conscious rats suppressed fever evoked by intracerebroventricular (icv) administration of prostaglandin E1 (PGE1, 50 ng). The V2 receptor agonist 1-desamino-8-D-AVP (40 pmol) injected into the meA evoked only moderate antipyresis compared with AVP, possibly because of interaction of this agonist with V1a receptors. The antipyretic effect of AVP was blocked when injection of the peptide was preceded by a bilateral injection of the V1a antagonist 1-(beta-mercapto-beta,beta-cyclopentamethylenepropionic acid)-2-(O-methyl)tyrosine AVP [d(CH2)5Tyr(Me)AVP, 400 pmol] into the meA. Injection of d(CH2)5Tyr(Me)AVP alone into the meA was without significant effect on afebrile core temperature. Injection of d(CH2)5Tyr(Me)AVP or 1-(beta-mercapto-beta,beta-cyclopentamethylenepropionic acid)-2-D-valine,4-valine AVP (a V2 antagonist) alone into the meA before icv PGE1 resulted in fevers that were not significantly different from artificial cerebrospinal fluid controls. These data are consistent with the possibility that AVP might act within the meA to evoke antipyresis via receptors that resemble V1a (vasopressor) receptors. However, the action of AVP endogenously released into the meA does not appear to be an absolute requisite in the normal modulation of PGE1 fever.

CNS vasopressin mediates emotional stress and CRH-induced colonic motor alterations in rats

The effects of emotional stress (ES) corresponding to conditioned fear on colonic motility and its antagonism by [deamino-Pen1, Val4, D-Arg8]vasopressin, a vasopressin antagonist, were investigated by electromyography in conscious fasted rats fitted with chronically implanted electrodes. A 117% increase (19.6 +/- 2.1 vs. 9.0 +/- 0.9 cycles/10 min during the control period) in the frequency of colonic spike bursts was observed when rats were placed for 30 min in a box in which they had previously received electric foot shocks. Intracerebroventricular (icv) administration of corticotropin-releasing hormone (CRH; 0.5 micrograms/kg) mimicked the effects of ES and increased the spike burst frequency of the colon by 88.6% from 5 to 15 min after its administration. At doses between 5 and 20 micrograms/kg the antagonist [deamino-Pen1, Val4, D-Arg8]vasopressin significantly reduced or abolished the effects of ES and CRH administration on colonic motility. Injected icv at doses of 2.5 and 5 ng/kg [Arg8]vasopressin dose dependently increased the frequency of colonic spike bursts. These effects were not reproduced by similar or higher (50 ng/kg) doses given intraperitoneally, and the effects were abolished after previous administration of vasopressin at a dose of 20 micrograms/kg. It is concluded that the effects of ES on colonic motility in rats previously shown to be linked to the central nervous system (CNS) release of CRH are in turn mediated through the central release of vasopressin.

Fluorescent peptide hormones: development of high affinity vasopressin analogues

Highly potent and specific peptide hormone analogues with fluorescent reporter groups are current research goals. Until now, however, only moderately potent analogues have been described. We report here several types of vasopressin (VP) analogues with different fluorophores attached to the peptide. In a first series, fluorophores were attached to the free epsilon amino function of [des-amino1-lysine8]VP (dLVP), producing agonistic analogues. In a second series, reporter groups were added to the N-terminal of open-chain antagonist structures. The biological activities of these analogues were assessed by two different sets of experiments: 1) The measurement of their binding affinities towards the V1a-vasopressin receptor subtype from WRK1 cells or rat liver membrane preparations; 2) Their ability to stimulate the phospholipase C activity in WRK1 cells. As expected, a simple acylation of fluorophores to dLVP resulted in a considerable loss of affinity. If however, the Lys8 side chain was extended through double Schiff-base formation with glutaraldehyde-ethylenediamine followed by reduction to an aminoalkyl aminoalkylamine, single fluorophores could be added without loss of affinity compared to VP. The open-chain analogues, on the other hand, while displaying weak affinity, nevertheless exhibited pure antagonistic behavior.

Administration of antidiuretic peptide (DDAVP) by way of suction de-epithelialised skin

Transdermal drug delivery seems a promising way of achieving complete, predictable absorption, but the epidermis is a barrier for most drugs. A new technique for transdermal drug delivery, in which a small patch of epidermis was removed, was tested in seven healthy volunteers by means of the antidiuretic peptide 1-deamino-8-D-arginine vasopressin (DDAVP). The epithelium of a small area of forearm skin (diameter 5 mm) was removed painlessly, and in a standard way, by a simple device operating at a present vacuum. DDAVP was given by way of improvised occlusive reservoirs. Plasma DDAVP concentration/time curves conformed closely with zero-order kinetics, which suggests that the bioavailability approached 100%, corresponding to that for direct intravenous infusion. Four volunteers were given DDAVP daily for 4 days by way of the de-epithelialised site; there were no signs that re-epithelialisation hindered permeation. All plasma DDAVP values substantially exceeded the lowest effective therapeutic concentration for patients with diabetes insipidus. The vacuum removal of the epithelium caused pronounced hyperaemia in the de-epithelialised dermis (assessed by laser doppler flow measurement); the hyperaemia persisted, unaffected by DDAVP, and may have contributed to the efficient permeation. The skin spot appeared normal at 6 weeks.

Effects of V2 receptor activity on the pressor response to vasopressin in the rat

1. To determine the contribution of V1 and V2 receptor activity on the enhancement of reflex buffering of the pressor response to arginine-vasopressin (AVP), mean arterial pressure (MAP) and heart rate (HR) changes were examined in response to graded injections of phenylephrine, AVP, or Phe2Orn8OT, a potent, selective V1-receptor agonist in the absence and presence of Val4DArg8VP, a potent, selective V2-receptor agonist. 2. There were no significant differences in MAP responses to the V1 agonist in the absence and presence of the V2 agonist in either conscious intact or autonomic-blocked rats. 3. Autonomic blockade with methscopolamine and hexamethonium increased the pressor sensitivity to phenylephrine threefold. In contrast, the pressor sensitivities to AVP and Phe2Orn8OT were increased 14-fold and 11-fold, respectively, by autonomic blockade. 4. V2-receptor activity does not have any inherent vasocative action or synergistic vasoactive action with V1-receptor activity. 5. V2 receptors do not play a role in enhancing reflex buffering of the pressor response to AVP; V1 receptors are suggested to play the role.

Sympathetic inhibition and attenuation of spontaneous hypertension by PVN lesions in rats

To determine whether the paraventricular nucleus (PVN) contributes to the development of hypertension in spontaneously hypertensive rats (SHR), we compared cardiovascular responses to ganglionic blockade with hexamethonium or vasopressin antagonism with dPVAVP in sham-operated or PVN lesioned SHR and Wistar-Kyoto rats (WKY). Lesions were produced electrolytically when the rats were 5 weeks old. During the next 3 weeks, tail-cuff measurements showed that the development of hypertension in SHR was inhibited, while systolic pressure in WKY was unaffected. Mean pressures recorded directly from the femoral artery at 8 weeks of age were lower in lesioned than in sham-operated SHR (141 +/- 5 vs 110 +/- 3 mm Hg, P less than 0.05), but did not differ in corresponding WKY groups (110 +/- 4 vs 112 +/- 5 mm Hg). Depressor responses to ganglionic blockade induced by i.v. injection of hexamethonium (25 mg/kg) were significantly larger in sham-operated than in lesioned SHR (-41 +/- 4% vs -28 +/- 3%, P less than 0.05). By contrast, vasopressin antagonism with dPVAVP did not alter blood pressure in all rat groups. In 24-h urine samples, excretion of vasopressin was unaffected, but that of norepinephrine was significantly reduced in lesioned SHR. These findings suggest that the PVN contributes to the development of spontaneous hypertension by sympathetic activation without increasing vasopressin secretion.

V2-like receptors mediate cerebral blood flow increase following vasopressin administration in rats

Experiments were performed on anesthetized (chloral hydrate) Wistar rats to determine the effect of vasopressin (VP) on cerebral blood flow (CBF), cerebral oxygen consumption (CMRO2), cerebrovascular resistance (CVR), and mean arterial blood pressure (MAP) before and after V1 or V2 VP receptor blockade. Influence of synthetic V2 receptor agonist (dVDAVP) on these variables was also tested. Intracarotid administration of 5 mU VP (Pitressin, n = 15) significantly increased CBF by 28% and CMRO2 by 27% and reduced CVR by 20% of control value. Intravenous (i.v.) infusion of dEt2AVP (V1 antagonist, 15 micrograms kg-1 h-1, n = 7) did not influence the effect of VP on CBF, CMRO2, and CVR but abolished MAP increase after VP. Intravenous (i.v.) infusion of d(CH2)5[D-Ile2,Abu4] AVP (V2 antagonist, 15 micrograms kg-1 h-1, n = 8) abolished the effect of VP on CBF, CMRO2, and CVR without changing its influence on MAP. Intracarotid administration of 12.5 ng dVDAVP (n = 7) increased CBF by 43% and CMRO2 by 29% and decreased CVR by 29% of control value. MAP was not affected. The results suggest that VP-induced CBF increase is, at least partly, caused by the rise of CMRO2 and mediated by V2-like receptors.

Oxytocin receptors in the oviduct during the oestrous cycle of the ewe

The presence of oxytocin receptors in ovine oviduct has been investigated. High-affinity binding sites for [3H]oxytocin were detected in crude membrane fractions prepared from the oviducts of ewes killed during the oestrous period. The dissociation constant calculated for these sites in competition studies was 1.7 nmol/l. Similar dissociation constants were calculated for [Arg8]-vasopressin and the oxytocin-specific agonists [Gly7]-oxytocin and [Thr4, Gly7]-oxytocin, indicating that these sites represent oxytocin receptors. At least one additional site of lower affinity and undetermined identity was present. The relative concentration of oxytocin-binding sites in preparations of oviduct membranes were estimated in ewes killed at different stages of the oestrous cycle using a single concentration of [3H]oxytocin. Binding was low during the luteal phase of the cycle but increased to a maximum at oestrus (77.7 fmol/mg protein). Binding fell after ovulation, reaching what appeared to be basal concentrations by the early luteal stage of the cycle. Binding to oviductal membranes from prepubertal, anoestrous and pregnant ewes was also low, but in anoestrous animals which had been treated with progesterone and oestrogen it was similar to values measured in ewes at oestrus. These results are consistent with the existence of oviductal oxytocin receptors which are regulated by ovarian steroids. We conclude that oxytocin receptors are present in the oviduct of the ewe around the time of ovulation. The significance of oxytocin to events taking place in the oviduct at this time remains to be determined.

Vasopressin receptors in human seminal vesicles: identification, pharmacologic characterization, and comparison with the vasopressin receptors present in the human kidney

Because of the presence of a high density of vasopressin receptors in the epithelial cells of porcine seminal vesicles similar to the V2 vasopressin receptors of renal tubules, human seminal vesicles and kidney were investigated using quantitative binding and adenylate cyclase studies. Tissues were obtained at surgery from 17 patients with urologic diseases. A homogeneous class of vasopressin binding sites have been found in both seminal vesicles and renal medulla. However, the vasopressin receptors present in these tissues are different in terms of ligand specificity and adenylate cyclase activation. In seminal vesicles, the V1 vasopressin antagonist d(CH2)5 TyrMeAVP is 36-fold, more potent than the V2 agonist dVDAVP in displacing [3H]AVP binding, while in the medullopapillary portion of kidney dVDAVP is 24-fold, more selective than d(CH2)5 TyrMeAVP for the arginine vasopressin binding site. Furthermore, arginine vasopressin induces a dose-dependent increase in adenylate cyclase activity in renal membranes, while it was ineffective in seminal vesicle membranes. These results indicate that a very high affinity (0.2 nM), low capacity (14 fmoles/mg protein) class of vasopressin receptors is present in human seminal vesicles, having pharmacologic characteristics similar to the V1 subtype of vasopressin receptors. The presence of a high affinity (1.6 nM), high capacity (350 fmoles/mg protein) V2 subtype of vasopressin receptors in human renal membranes is also confirmed. The density of the vasopressin receptors present in human seminal vesicles is inversely correlated with patient age, consistent with a physiologic role for vasopressin in the regulation of accessory sex gland activity.

2-O-alkyltyrosine derivatives of 1-deamino-arginine-vasopressin: highly specific and potent antidiuretic agonists

We report the solid-phase synthesis of eight 2-O-alkyltyrosine analogues of 1-deamino-arginine-vasopressin (dAVP) with enhanced antidiuretic agonistic specificity. These peptides are as follows: 1-deamino[2-O-methyltyrosine]-arginine-vasopressin (dTyr(Me)AVP), 1-deamino[2-O-ethyltyrosine]arginine-vasopressin (dTyr(Et)AVP), 1-deamino[2-O-methyltyrosine,8-D-arginine]vasopressin (dTyr(Me)DAVP), 1-deamino[2-O-ethyltyrosine,8-D-arginine]vasopressin (dTyr(Et)DAVP), 1-deamino[2-O-methyltyrosine,4-valine]arginine-vasopressin (dTyr(Me)VAVP), 1-deamino[2-O-ethyltyrosine,4-valine]arginine-vasopressin (dTyr(Et)VAVP), 1-deamino[2-O-methyltyrosine,4-valine,8-D-arginine]vasopressin (dTyr(Me)VDAVP), and 1-deamino[2-O-ethyltyrosine,4-valine,8-D-arginine]vasopressin (dTyr(Et)VDAVP). All analogues were tested for antidiuretic, antivasopressor, and antioxytocic activities. Deamination, as was expected, significantly enhanced the antidiuretic properties of these analogues relative to their parent N-amino-O-alkyltyrosine peptides. With the exception of dTyr(Me)AVP, all of these analogues are antagonists of the vasopressor responses to AVP and of the uterine response to oxytocin. Thus they all exhibit high antidiuretic agonistic specificity. Due to its remarkable properties, dTyr(Me)VDAVP is a unique compound in this series. It appears to be the most potent antidiuretic agonist (1740 units/mg) and also a vasopressor antagonist and a potent oxytocin antagonist. It is thus a highly specific antidiuretic agonist. In general, all of these new analogues are highly specific and thus are potentially useful as pharmacological tools and clinical agents.

Acquired von Willebrand's syndrome due to an inhibitor of IgG specific for von Willebrand's factor in polycythemia rubra vera

A patient with acquired von Willebrand's syndrome associated with polycythemia rubra vera is described. Ristocetin cofactor activity was decreased, while the levels of vWF:Ag and VIII:C were normal. Crossed immunoelectrophoretic analysis showed that vWF:Ag was composed of much more anodic component. The mixture study using pooled normal plasma and the patient IgG fractions showed the inhibition of ristocetin cofactor and the decrease of less anodic parts of vWF:Ag in normal plasma. After 1-deamino-8-arginine vasopressin (DDAVP) infusion the marked increases of vWF:Ag, VIII:C and ristocetin cofactor and a rapid return of ristocetin cofactor to the baseline were observed. Transient increase of vWF:Ag after DDAVP infusion showed less anodic forms and in the relative proportion as normal plasma. The present study showed that the patient IgG fractions had the specific inhibitory activity against the antigenic sites on the active subfractions of von Willebrand's factor.

Vasopressin and oxytocin reduce plasma prolactin levels of conscious rats in basal and stress conditions. Study of the characteristics of the receptor involved

Subcutaneous administration of arginine vasopressin (AVP) to conscious rats induced a dose-dependent increase of plasma ACTH and beta-endorphin levels and decrease of plasma prolactin (PRL) levels 30 min later. AVP similarly reduced PRL increase induced by exposure to a novel environment stress. Oxytocin (OT) was also active but 5-fold less potent than AVP. The study of several analogs with specific agonistic and antagonistic activity on the oxytocic, vasopressor and antidiuretic receptors of OT and AVP suggests that the receptor involved in this effect does not fit into this classification.

Atriopeptin turnover: quantitative relationship between in vivo changes in plasma levels and atrial content

Administration of the 1-deamino-arginine8 vasopressin caused a decrease in right, but not left, atrial levels of atriopeptin (AP) in chloral hydrate-anesthetized rats. The amount of exogenous AP required to match the 1-deamino-arginine8 vasopressin-stimulated plasma levels of AP was equivalent to the decrease in AP content of the right atrium, suggesting that resynthesis of AP did not occur within the 60 min after 1-deamino-arginine8 vasopressin stimulation. The correlation between increased plasma levels and decreased atrial content was also observed in bilaterally nephrectomized rats, suggesting that the kidney is not a major site of degradation of AP in vivo. This finding was confirmed by the comparison of the half-life of exogenous AP in normal (T1/2 = 31 sec) and nephrectomized (T1/2 = 64 sec) animals. Plasma immunoreactivity of the N-terminal fragment of the prohormone (which is also released after cleavage of the precursor peptide) increased 35-fold by 24 hr after nephrectomy in comparison with a 5-fold increase in AP. Half-life studies of the N-terminal fragment suggest that the kidney is the major site of degradation of this molecule. This study demonstrated the different kinetics and renal metabolism of the AP and N-terminal portions of the prohormone.

Characterization of vasopressin receptors of rat urinary bladder and spleen

By use of tritiated arginine-8-vasopressin (AVP), vasopressin specific binding sites were detected on Sprague-Dawley rat urinary bladder and spleen. In both tissues, one class of high-affinity binding sites was characterized with an equilibrium dissociation constant of 1.61 +/- 0.22 and 1.91 +/- 0.16 nM and a maximal binding capacity of 155 +/- 5 and 110 +/- 11 fmol/mg of protein, for bladder and spleen, respectively. In both tissues, several experimental arguments suggest that these receptors belong to the V1-vascular type: Highly significant correlations were found between the relative agonistic vasopressor activities of eight AVP agonists and their relative abilities to inhibit [3H]AVP binding to the receptors, whereas no such relationship existed when antidiuretic activities were considered. The same profile was also observed with the antagonistic activities of five AVP antagonists. Moreover, AVP (10(-12)-10(-5) M) did not modify the basal cyclic AMP production in either tissue. As cyclic AMP is known to respond to V2 stimulation, the data suggest that the receptors measured are the V1 type. In Dahl rats the receptor characteristics were modulated by salt diet. More interestingly, the number of spleen vasopressin binding sites was always lower in Dahl salt-resistant animals than in the Dahl salt-sensitive animals receiving either a sodium deficient or a 1% NaCl or an 8% NaCl-containing diet. The exploration of vasopressin receptors regulation should facilitate the comprehension of the role played by AVP in different models of experimental hypertension.

Effect of vasopressin, oxytocin and peptides derived from these hormones on field potential induced in lateral septum of rats by stimulation of the fimbria fornix

Superfusion of the dorsal surface of the septum with artificial cerebrospinal fluid containing 10(-10) M [Arg8]-vasopressin (VP) significantly increased the negative (N) wave in field potentials (FPs) elicited in the lateral septum (LS) of rats by stimulation of the fimbria-fornix. A similar increase in the FPs negativity was also observed following superfusion of the septum with [pGlu4, Cyt6] VP(4-9), [pGlu4, Cyt6] VP(4-8), [Cyt6] VP (5-9), desglycinamide9-VP and 1-deamino, 8-D-arginine-VP. However, for obtaining the effect with these peptides 10(3-4) times higher concentrations had to be used. Superfusion of the septum with 10(-8) M oxytocin (OX) elicited nearly the same N-wave increase as the 10(-8) M VP septal superfusion. The 10(-10) M concentration of OX as well as 10(-7) M [pGlu4, Cyt6] OX(4-9) and [pGlu4, Cyt6] OX(4-8) had little effect on the FPs negativity. The significance of these findings for the elucidation of the VP function in the LS is discussed.

Effects of AVP and DDAVP on histamine-induced increases in macromolecular permeability in the hamster cheek pouch

The effects of histamine alone and in the presence of AVP or DDAVP on microvascular permeability to macromolecules was evaluated in the superfused hamster cheek pouch. FITC-Dextran (MW 70,000) was employed as a macromolecular tracer to quantitate the increase in macromolecular permeability produced by the topical application of histamine. Intra-vital light microscopy was utilized to quantitate and localize FITC-D extravasation sites along the vascular tree, and fluorimetric measurement of the FITC-D concentration in the suffusate (S) and plasma (P) was used to calculate the FITC-D S/P ratio to quantitate the increase in macromolecular permeability. The infusion of histamine for 5 minutes at a rate which produced a suffusate histamine concentration of 1 X 10(-5) M produced a marked increase in the number of venular FITC-D leakage sites, the [FITC-D]s, and the FITC-D S/P ratio. These effects of histamine were prevented by treatment with either AVP or DDAVP which was infused at a rate sufficient to produce a suffusate concentration of 1 X 10(-8) M. AVP produced profound vasoconstriction whereas DDAVP prevented the histamine-induced increase in the formation of venular FITC-D leakage sites, the [FITC-D]s, and FITC-D S/P ratio without producing vasoconstriction. These data suggest that the antagonism of the histamine-induced increase in macromolecular permeability by AVP and DDAVP is not dependent on vasoconstriction per se, but rather is attributable to the stimulation of a vasopressin receptor on the venular endothelial cell which is identical to or similar to the vasopressin receptor mediating the anti-diuretic effects of these agents.

Effects of a nonpressor analogue of vasopressin on plasma renin activity and salt and water excretion in water-loaded, anesthetized dogs

The object of this study was to determine the importance of vasoconstrictor activity in the suppression of renin secretion by vasopressin. Arginine vasopressin (AVP) (0.05 and 0.1 ng/kg/min) and a nonpressor analogue of vasopressin, 1-deamino-[4-threonine, 8-D-arginine]-vasopressin (dTDAVP) (0.01 and 0.05 ng/kg/min), were infused intravenously in anesthetized hypophysectomized dogs. Neither dTDAVP nor AVP influenced arterial pressure or heart rate but both suppressed plasma renin activity. Infusion of dTDAVP at 0.01 and 0.05 ng/kg/min suppressed plasma renin activity to 86 +/- 4% (p less than 0.05) and 63 +/- 6% (p less than 0.01) of the control values respectively. Infusion of AVP at 0.05 and 0.1 ng/kg/min suppressed plasma renin activity to 60 +/- 8% (p less than 0.01) and 59 +/- 12% (p less than 0.05) of the control values respectively. dTDAVP and AVP both produced significant increases in sodium excretion. These data demonstrate that vasoconstrictor activity is not required for the effects of vasopressin on renin secretion and sodium excretion.

1-deamino-/4-valine-8-D-arginine/-vasopressin (dVDAVP), a new synthetic vasopressin analog for treating diabetes insipidus

The effects of LVP, dDAVP, and dVDAVP on the water excretion of 14 vasopressin-sensitive and 2 ADH-resistant patients with diabetes insipidus were studied and compared. Findings showed that dDAVP and dVDAVP decreased the diuresis of all ADH-sensitive patients, and in those with diabetes insipidus, more markedly (7.6-fold) and for a longer duration (3.3-fold) than did LVP. From a comparison of the results, dVDAVP is at present one of the most effective preparations for reduction of polyuria in patients with ADH-sensitive diabetes insipidus.

The effects of water deprivation and water loading during treatment with 1-deamino-8-D-arginine vasopressin in central diabetes insipidus in childhood

Nine children aged 7 2/12 to 17 9/12 years with central diabetes insipidus were subjected to water deprivation and water loading during treatment with 1-deamino-8-D-arginine vasopressin (DDVAP). Urine output remained unchanged despite the large differences in water intake. Serum osmolarity was not significantly affected by water deprivation. However, there was a marked decrease in serum osmolarity during water loading. This not accompanied by any symptoms of haemodilution. Thus patients apparently tolerate large variations in fluid intake during therapy with DDVAP.

Effects of vasopressin analogues (DDAVP, DVDAVP) in the form of sublingual tablets in central diabetes insipidus

The effects of 1-deamino-8-D-arginine vasopressin (DDAVP), 1-deamino-4-valin-8-D-arginine vasopressin (DVDAVP) and 8-arginine vasopressin (AVP) on water metabolism have been examined in 18 patients suffering from central diabetes insipidus. The hormone derivatives were sublingually administered. It was established that DDAVP and DVDAVP significantly reduced diuresis and increased urine osmolarity. DVDAVP was found to be more effective than DDAVP. AVP administered in equal doses had no significant effect on water metabolism. The duration of the action of sublingually administered DDAVP was 12 hrs; after dosing DVDAVP the effect lasted even 6 hrs. During one week of DDAVP administration, the accumulation of the drug was indicated by the gradual decrease of diuresis and the increase of the urine osmolarity. The sublingual administration of both DDAVP and DVDAVP tablets (3 X 30 micrograms/day) had an adequate therapeutic effect.

A model for the study of the oral administration of peptide hormones

The intragastric administration of lysine vasopressin (LVP) to rats is used as a model to study the biological activity of orally administered peptide hormones. Using a modification of the antidiuretic assay of Sawyer, LVP given by stomach tube caused a significant antidiuresis that was dose dependent in doses of 300 to 2000 mU. The simultaneous administration of the protease inhibitor, Trasylol, increased the antidiuretic effect of LVP. The synthetic peptide (1-deamino, 4 valine)-8-D-arginine-vasopressin also caused a dose-dependent prolonged and significant antidiuresis. No pressor effect was observed after intragastric administration of LVP in doses up to 40 U/rat. We are now using this model to test other procedures for enhancing the activity of lysine vasopressin administered in the gastrointestinal tract such as encapsulation into liposomes. The information gained with vasopressin will then be applied to insulin with the ultimate goal of making oral administration practical.

Vasopressin analog with extraordinarily high antidiuretic potency: a study of conformation and activity

Application of information derived from a three-dimensional model of vasopressin bound to its antidiuretic receptor has resulted in the design and synthesis of a potent analog, [1-deamino, 2-phenylalanine, 7-(3,4-dehydroproline)]-arginine vasopressin; this analog has a specific antidiuretic activity of 13,000 +/- 1,250 units per milligram; noteworthy at these doses is the absence of any detectable pressor activity. Three modifications based on conformational considerations were introduced into the vasopressin molecule in preparing the analog: (i) to enhance binding, a double bond was introduced into the side chain of an amino acid residue occupying a corner position of a beta turn in the vasopressin conformation, (ii) the hydroxyl moiety was deleted from Tyr2, and (iii) to tighten the backbone structure and to enhance the enzymatic resistance of the analog, the NH2-terminal amino group was deleted.