Clinical profiles of post-load glucose subgroups and their association with glycaemic traits over time: An IMI-DIRECT study.

AIM: To examine the hypothesis that, based on their glucose curves during a seven-point oral glucose tolerance test, people at elevated type 2 diabetes risk can be divided into subgroups with different clinical profiles at baseline and different degrees of subsequent glycaemic deterioration. METHODS: We included 2126 participants at elevated type 2 diabetes risk from the Diabetes Research on Patient Stratification (IMI-DIRECT) study. Latent class trajectory analysis was used to identify subgroups from a seven-point oral glucose tolerance test at baseline and follow-up. Linear models quantified the associations between the subgroups with glycaemic traits at baseline and 18 months. RESULTS: At baseline, we identified four glucose curve subgroups, labelled in order of increasing peak levels as 1-4. Participants in Subgroups 2-4, were more likely to have higher insulin resistance (homeostatic model assessment) and a lower Matsuda index, than those in Subgroup 1. Overall, participants in Subgroups 3 and 4, had higher glycaemic trait values, with the exception of the Matsuda and insulinogenic indices. At 18 months, change in homeostatic model assessment of insulin resistance was higher in Subgroup 4 (ß = 0.36, 95% CI 0.13-0.58), Subgroup 3 (ß = 0.30; 95% CI 0.10-0.50) and Subgroup 2 (ß = 0.18; 95% CI 0.04-0.32), compared to Subgroup 1. The same was observed for C-peptide and insulin. Five subgroups were identified at follow-up, and the majority of participants remained in the same subgroup or progressed to higher peak subgroups after 18 months. CONCLUSIONS: Using data from a frequently sampled oral glucose tolerance test, glucose curve patterns associated with different clinical characteristics and different rates of subsequent glycaemic deterioration can be identified.

Dulaglutide decreases plasma aminotransferases in people with Type 2 diabetes in a pattern consistent with liver fat reduction: a post hoc analysis of the AWARD programme.

AIMS: To evaluate the effects of dulaglutide vs placebo on liver and glycaemic/metabolic measurements in a population with Type 2 diabetes and in a subgroup with non-alcoholic fatty liver/non-alcoholic steatohepatitis. METHODS: A total of 1499 participants from AWARD-1, AWARD-5, AWARD-8 and AWARD-9 clinical trials were included in this analysis (dulaglutide 1.5 mg, n=971 and placebo, n=528). Thresholds of alanine aminotransferase levels ≥30 IU/l in men and ≥19 IU/l in women were used to determine the subgroup who had non-alcoholic fatty liver/non-alcoholic steatohepatitis. Objectives included changes from baseline to 6 months in: (1) alanine aminotransferase, aspartate transaminase and gamma-glutamyl transpeptidase levels in the overall population and (2) alanine aminotransferase, aspartate transaminase, gamma-glutamyl transpeptidase and glycaemic/metabolic measurements (e.g. HbA1c , fasting serum glucose, body weight, lipids and homeostatic model assessment) in the non-alcoholic fatty liver/non-alcoholic steatohepatitis subgroup. RESULTS: In the overall population at 6 months, dulaglutide significantly reduced alanine aminotransferase, aspartate transaminase and gamma-glutamyl transpeptidase levels vs placebo [least squares mean treatment differences: -1.7 IU/l (95% CI -2.8, -0.6), P=0.003; -1.1 IU/l (95% CI -2.1, -0.1), P=0.037; -6.6 IU/l (95% CI -12.4, -0.8), P=0.025, respectively]. In the subgroup with non-alcoholic fatty liver/non-alcoholic steatohepatitis (alanine aminotransferase levels greater than or equal to the upper limit of normal), mean baseline liver enzyme values were 38.0 IU/l, 27.8 IU/l and 43.9 IU/l for alanine aminotransferase, aspartate transaminase and gamma-glutamyl transpeptidase, respectively. In this population, more pronounced reductions from baseline in alanine aminotransferase were observed with dulaglutide vs placebo (-8.8 IU/l vs -6.7 IU/l). In the subgroup of people with alanine aminotransferase levels less than the upper limit of normal, changes from baseline in alanine aminotransferase did not significantly differ between treatment groups (0.0 IU/l vs 0.7 IU/l). CONCLUSIONS: Once-weekly dulaglutide improved alanine aminotransferase, aspartate transaminase and gamma-glutamyl transpeptidase levels compared with placebo in a pattern consistent with liver fat reductions. Our results add further weight to the notion that glucagon-like peptide-1 receptor agonists may provide benefit in lowering liver fat in addition to their other metabolic actions.

Vitamin D and calcium supplementation for three years in postmenopausal osteoporosis significantly alters bone mineral and organic matrix quality.

Prospective, controlled clinical trials in postmenopausal osteoporosis typically compare effects of an active drug with placebo in addition to vitamin D and calcium supplementation in both treatment arms. While clinical benefits are documented, the effect of this supplementation in the placebo arm and in clinical practice on bone material composition properties is unknown. The purpose of the present study was to evaluate these bone quality indices (specifically mineral/matrix, nanoporosity, glycosaminoglycan content, mineral maturity/crystallinity, and pyridinoline content) in patients that either received long-term vitamin D (400-1200IU) and calcium (1.0-1.5g) supplementation, or did not. We have analyzed by Raman microspectroscopy the bone forming trabecular surfaces of iliac crest in pre-treatment samples of a teriparatide study and the endpoint biopsies of the control arm obtained from the HORIZON trial. In general, the mineral/matrix ratio and the glycosaminoglycan (GAG) content was higher while nanoporosity, (a surrogate for tissue water content), the mineral maturity/crystallinity (MMC) and the pyridinoline (Pyd) content was lower in patients without long-term supplementation. Moreover, all indices were significantly dependent on tissue age. In conclusion, vitamin D and calcium supplementation is associated with altered mineral and organic matrix properties.

Bone quality of the newest bone formed after two years of teriparatide therapy in patients who were previously treatment-naïve or on long-term alendronate therapy.

UNLABELLED: The results of the present study, involving analysis of biopsies from patients who received teriparatide for 2 years and were previously either treatment-naïve or on long-term alendronate therapy, suggest that prior alendronate use does not blunt the favorable effects of teriparatide on bone quality. INTRODUCTION: Examine the effect of 2 years of teriparatide (TPTD) treatment on mineral and organic matrix properties of the newest formed bone in patients who were previously treatment-naïve (TN) or on long-term alendronate (ALN) therapy. METHODS: Raman and Fourier transform infrared microspectroscopic analyses were used to determine the mineral/matrix (M/M) ratio, the relative proteoglycan (PG) content, and the mineral maturity/crystallinity (MMC; determined by three methods: carbonate content, full width at half height of the v 1 PO4 band [FWHH], and wavelength at maxima of the v 1 PO4 band), as well as collagen maturity (ratio of pyridinoline/divalent cross-links), in paired iliac crest biopsies at trabecular, endosteal, and osteonal surfaces of newly formed bone in postmenopausal osteoporotic women who were previously either TN (n = 16) or receiving long-term ALN treatment (n = 24). RESULTS: Trabecular M/M ratio increased and matrix content decreased significantly in the ALN pretreated group. Collagen maturity decreased in both patient groups. Endosteal M/M ratio increased significantly in the TN group. Trabecular M/M ratio was higher at endpoint in the ALN pretreated group than in the TN group. Overall, no changes from baseline were observed in PG content, except that PG content was higher in the ALN pretreated group than in the TN group at endosteal surfaces at endpoint. The ability of TPTD treatment to reduce MMC in both patient groups and at the different bone surfaces depended on the measurement tool (relative carbonate content or wavelength at maxima of the v 1 PO4 band). None of the changes in MMC were different between the two patient groups. CONCLUSIONS: The results suggest some favorable impact of TPTD on bone mineral and organic matrix properties of in situ forming bone in terms of increased initial mineralization and decreased MMC and collagen maturity. Moreover, prior long-term ALN administration may have only limited influence on these properties in bone newly formed after 2 years of TPTD treatment.

Histomorphometric changes by teriparatide in alendronate-pretreated women with osteoporosis.

SUMMARY: The level of increased bone formation after 24 months of treatment with teriparatide (rhPTH (1-34), TPTD) is similar in patients who were either treatment-naïve (TN) or had lower bone turnover initially due to previous alendronate (ALN) therapy. INTRODUCTION: Bone anabolic effects of TPTD in postmenopausal women with osteoporosis may be blunted during the initial phase after switching from ALN to TPTD. To explore the long-term implications, we examined histomorphometric and biochemical markers of bone turnover of patients on TPTD therapy after long-term ALN treatment. METHODS: Paired biopsies were obtained after tetracycline double labeling at baseline and after 24 months of TPTD treatment from 29 ALN-pretreated (64.5 ± 16.4 months) and 16 TN patients. Biochemical markers were measured at baseline, during the treatment, or at study end. RESULTS: Compared with the baseline, after 24-month TPTD, activation frequency (Ac.F.) and osteoid surface (OS) increased in both groups: 0.11-0.34 cycles per year, 3.96-9.8% in the ALN-pretreated group and 0.19-0.33 cycles per year, 6.2-11.3% (p < 0.05) in the TN group, respectively. Biochemical and histomorphometric markers correlated positively both at baseline and endpoint. Serum amino terminal propeptide of type I procollagen (PINP) correlated with Ac.F. (r = 0.57, p < 0.001 and r = 0.48, p < 0.01) and OS (r = 0.51, p < 0.01 and r = 0.56, p < 0.01) at baseline and endpoint, respectively. Following 3 months of treatment, increases in biochemical markers like PINP predicted the increase in Ac.F. (r = 0.52, p < 0.01) and OS (r = 0.54, p < 0.01) after 24 months. CONCLUSIONS: The increased level of formation is similar in patients who were either TN or had lower bone turnover initially due to previous ALN therapy. Elevated bone formation in postmenopausal women with osteoporosis was sustained over a 24-month period by TPTD. Biochemical markers of bone formation are a good surrogate for the assessment of TPTD effects.

Protective effect of ischaemic preconditioning on ischaemia/reperfusion-induced microvascular obstruction determined by on-line measurements of coronary pressure and blood flow in pigs.

We investigated the protective effect of ischaemic preconditioning (IP) on the maintenance of coronary patency using on-line measurements of coronary pressures and blood flow in a closed-chest reperfused acute myocardial infarction (MI) model in pigs. Catheter-based 90-min occlusion followed by 60-min reperfusion of the left anterior descending coronary artery (LAD) was performed in anesthetised pigs (MI group). IP was applied (IP group) through two cycles of 5-min occlusion and 5-min reperfusion of the LAD before MI induction. Coronary patency was determined by measurements of coronary wedge pressure, collateral fractional flow reserve (FFRcoll), collateral pressure index (CPI) and absolute coronary blood flow (CBF). Inducible and constitutive nitric oxide synthase (iNOS/cNOS) activities and expressions were determined in the myocardium. Plasma levels of myeloperoxidase (MPO, index of activated leukocytes) and mean platelet volume (MPV, index of activated platelets) were measured. IP resulted in significantly lower levels of MPO (0.52 +/- 0.19 vs. 1.05 +/- 0.24 U/l, p<0.001) and MPV (9.1 +/- 0.6 vs. 9.6 +/- 1.0 fl, p=0.04), higher FFRcoll (0.17 +/- 0.05 vs. 0.04 +/- 0.05, p<0.001), CPI (0.13 +/- 0.05 vs. 0.02 +/- 0.05, p<0.001) and CBF (70.7 +/- 4.2 vs. 50.8 +/- 4.8 m/min, p<0.001) post-reperfusion as compared with the MI group. IP resulted in significantly higher cNOS activity and eNOS expression. Significant negative correlation was found between MPO and measures of coronary patency (FFRcoll, CPI and CBF) and cNOS activity. Moreover, cNOS activity correlated significantly with FFRcoll, CPI and CBF. In conclusion, IP attenuates the release of MPO and platelet activation, thereby contributing to the maintenance of vessel patency at microvascular level after reperfusion of the infarct-related artery.

Tracking the migration of cardially delivered therapeutic stem cells in vivo: state of the art.

Cell-based therapy is a promising, novel therapeutic strategy for cardiovascular disease. The rapid transition of this approach from the benchside to clinical trials has left a gap in the understanding of the mechanisms of cell therapy. Monitoring of cell homing and the fate of cardially delivered stem cells is fundamental for clarification of the myocardial regenerative process. Noninvasive imaging techniques allow an in vivo evaluation of the survival, migration and differentiation of implanted stem cells over time, and by this means, can help to answer unresolved questions. The most promising in vivo tracking methods involve the direct, nonspecific labeling of cells including MRI, radionuclide imaging and the use of reporter-gene imaging. This review summarizes the most important results of animal and human studies in which the fate and biodistribution of cardially delivered stem cells are assessed through different in vivo tracking methods.

Patient compliance with alendronate, risedronate and raloxifene for the treatment of osteoporosis in postmenopausal women.

OBJECTIVES: The aim was to investigate patient compliance with different osteoporosis medications commonly prescribed in clinical practice, to determine risk factors associated with discontinuation and to evaluate quality of life changes. RESEARCH DESIGN AND METHODS: We conducted a 1-year observational study of patients of age > or = 60 years in a clinical setting at 917 sites in 10 European countries (Germany, Greece, UK, Sweden, Netherlands, Romania, Norway, Finland, Denmark, Estonia), Lebanon and South Africa. Demographic data, concomitant diseases, the reasons for intervention, educational, socio-economical status and disease knowledge were captured at baseline. Self-reported compliance, discontinuation data and health status were collected. MAIN OUTCOME MEASURES: Out of 5198 patients, 3490 (67.1%) patients received 60 mg daily raloxifene (RAL), 452 (8.7%) 10 mg daily alendronate (AQD), 769 (14.8%) 70 mg once weekly alendronate (AQW) and 487 (9.4%) 5 mg daily risedronate (RIS). Among patients completing the study (4231, 81%), the percentage of patients with high compliance was 80% (RAL), 79% (AQD), 65% (AQW) and 76% (RIS). The discontinuation due to side effects was highest on AQW (7.0%), followed by AQD (6.4%), RAL (3.8%) and RIS (3.4%). The discontinuation-rate was higher for patients with a history of surgical menopause, increased age, lack of knowledge about medical prevention of osteoporosis and thin frame as a reason for intervention. The EQ-5D weighted index showed the highest improvement for RIS (0.13), followed by RAL (0.11), AQD (0.08) and AQW (0.07). CONCLUSIONS: Data from this non-interventional observational study indicate moderate overall compliance and discontinuation rate with the prescribed osteoporosis medications.

Inhibitory effect of galanin on dopamine induced increased oxytocin secretion in rat neurohypophyseal tissue cultures.

The regulation of oxytocin (OT) release by galanin (GAL) at the neurohypophyseal (NH) nerve terminal is not adequately understood. The effect of GAL on the secretion of OT was studied in 13- to 14-day cultures of isolated rat NH tissue. By this time, the hormone content of the medium had become constant. The OT content of the supernatant medium was determined by RIA after a 1- or 2-h incubation. A significantly decreased content of OT was found following incubation with 10(-6)-10(-8) M doses of GAL. Dopamine (DA) and the DA-active drugs apomorphine (APM) and Pro-Lys-Gly (PLG) (10(-6) M in each medium) increased the OT synthesis of NH tissue cultures. This elevation of OT secretion could be blocked by the administration of GAL together with DA, APM or PLG. The DA-blocking effect of GAL was prevented by previous treatment with the GAL receptor antagonist galantid (M15). The results indicate that OT release from the NH is directly influenced by the GAL-ergic system. The GAL-ergic control of OT secretion from NH tissue in rats can occur at the level of the posterior pituitary.

Inhibitory effect of galanin on dopamine-induced enhanced vasopressin secretion in rat neurohypophyseal tissue cultures.

The effect of galanin (GAL) on vasopressin (VP) secretion was studied in 13-14-day cultures of isolated rat neurohypophyseal (NH) tissue. The VP content of the supernatant was determined by radioimmunoassay (RIA) after a 1- or 2-h incubation. A significantly decreased content of VP was detected following the administration of 10(-6)-10(-9) M doses of GAL. Dopamine (DA) and the DA-active drugs apomorphine (APM) and Pro-Lys-Gly (PLG) (10(-6) M in each medium) increased the VP level of NH tissue cultures. This VP concentration elevation could be blocked by the administration of GAL together with DA, APM or PLG. The DA-blocking effect of GAL was prevented by previous treatment with the GAL receptor antagonist galantid (M15). The results indicate that VP release is directly influenced by the GAL-ergic system. The GAL-ergic control of VP secretion from NH tissue in rats can occur independently of the hypothalamus, at the level of the posterior pituitary.

Endogenous bacteria-triggered inducible nitric oxide synthase activation protects the ovariectomized rat stomach.

Under experimental circumstances, ovariectomy attenuates gastric mucosal injury where nitric oxide (NO)-mediated pathways are involved. In this study, we have examined the changes in constitutive (cNOS) and inducible NO synthase (iNOS) enzyme activities (assessed by the citrulline assay), and the role of endogenous bacteria in ovariectomy-provoked mucosal defence. Gastric lesions were induced by indomethacin (50 mg/kg, s.c.) over a 4 h period in sham-operated and ovariectomized female Wistar rats. Groups of animals received the wide-spectrum antibiotic ampicillin (800 mg/kg/day, p.o., for 3 days), and others were injected with bacterial endotoxin (E. coli, 3 mg/kg, i.v., 5 h before autopsy). We found that ovariectomy increased iNOS and decreased cNOS activity (resulting an elevated total gastric NOS level), and protected the stomach, effects reversed by ampicillin treatment. In ovary-intact rats, administration of bacterial endotoxin enhanced gastric iNOS activity and reduced lesion-formation. These results suggest that ovariectomy improves gastric mucosal defence perhaps by endogenous bacteria-triggered induction of iNOS.

Vasopressin pressor receptor-mediated activation of HPA axis by acute ethanol stress in rats.

The plasma arginine vasopressin (AVP), ACTH, and corticosterone levels and the hypothalamic corticotropin-releasing hormone (CRH) content were measured after oral administration of 1 ml of 75% ethanol to rats, a model known to induce acute gastric erosions and stress. Elevated plasma AVP, ACTH, and corticosterone levels were detected 1 h after ethanol administration. Treatment with the vasopressin pressor (V(1)) receptor antagonist [d(CH(2))(5)Tyr(Me)-AVP] before ethanol administration significantly reduced the ACTH and corticosterone level increases. A higher hypothalamic CRH content was measured at 30 or 60 min after ethanol administration. V(1) receptor antagonist injection, 5 min before ethanol administration, inhibited the rise in hypothalamic CRH content. The protein synthesis blocker cycloheximide prevented the hypothalamic CRH content elevation after stress. The AVP-, CRH-, and AVP + CRH-induced in vitro ACTH release in normal anterior pituitary tissue cultures was also prevented by pretreatment with the V(1) receptor antagonist. The results support the hypothesis that stress-induced AVP may not only act directly on the ACTH producing anterior pituitary cells but also indirectly at the hypothalamic level via the synthesis and release of CRH.

Estrogen-mediated up-regulation of the Ca-dependent constitutive nitric oxide synthase in the rat aorta and heart.

The role of endogenous estrogens has been studied in the regulation of the Ca-dependent constitutive nitric oxide synthase (cNOS) enzyme activity in aortic and cardiac tissues of the rat. The activity of cNOS enzyme was measured by the citrulline assay in the abdominal aorta and in the left ventricle of the heart obtained from male, sham-operated female and ovariectomized female Wistar rats. Estrogen replacement therapy (17-beta-estradiol, 20-100 microg/kg/day, s.c.) has been performed in ovariectomized rats over two weeks. We found that cNOS activity was higher in the aorta and heart of female rats compared to males. Ovariectomy decreased cNOS activity in both tissues to that level what could be observed in males. Estrogen supplementation caused a dose-dependent elevation of cNOS enzyme activity in cardiac and aortic tissues, where the higher dose (100 microg) completely restored cNOS enzyme activity to the levels found in females. We concluded that endogenous estrogens up-regulate the activity of the cNOS isoenzymes in the rat aorta and heart.

Interactions of pro-inflammatory and vasoactive mediators with nitric oxide in the regulation of rat vascular permeability during laparotomy.

Inhibition of constitutive nitric oxide (NO) synthases by administration of N(G)-nitro-L-arginine methyl ester (L-NAME) during abdominal laparotomy provokes extensive vascular leakage in the rat gastrointestinal tract, assessed by the extravasation of [125I]human serum albumin. In the present study, the role of vasoactive or neutrophil-derived pro-inflammatory mediators in this process has been investigated. Administration of the thromboxane synthase inhibitor, 1-benzyl-imidazole (BZI, 25-50 mg kg(-1), s.c.), the platelet-activating factor (PAF) receptor antagonist, 3-[4-(2-chlorophenyl)-9-methyl-6H-thienol-[3,2-f][1,2,4]-triazolo- [4, 3-a][1,4]-diazepine-2-yl]-1-(4-morpholynil)-1-propionate (WEB 2086; 0.5-1 mg kg(-1), s.c.), the 5-lipoxygenase synthase inhibitor, N-(4-benzyloxybenzyl)-acetohydroxamic acid (BW A137C; 4-20 mg kg(-1), s.c.) or the vasopressin pressor receptor antagonist ([Mca(1), Tyr(Me)(2),Arg(8)]vasopressin/Manning peptide; 0.01-0.2 microg kg(-1), s.c.) dose-dependently reduced the intestinal plasma leakage provoked by L-NAME (5 mg kg(-1), s.c.), following a 5-cm abdominal laparotomy in anaesthetised rats. These findings suggest that constitutive NO synthase effectively counteracts the damaging actions on microvascular integrity of mediators, including thromboxanes, PAF, leukotrienes and vasopressin, released during surgical intervention.

Nitric oxide-mediated mucus hypersecretion protects the stomach of ovariectomized rats.

The actions of ovariectomy on nitric oxide synthase (assessed by the citrullin assay), mucus secretion (assessed by the Alcyan blue technique) and ulcerogenic response (indomethacin (30 mg kg(-1), s.c. , 4 h) or cysteamine (400 mg kg(-1), s.c., 24 h)) were studied in the female rat stomach. Ovariectomy increased nitric oxide synthase and mucus secretion, and decreased the severity of lesions, effects reversed by the nitric oxide synthase inhibitor, N(G)-nitro-L-arginine methyl ester (L-NAME, 10 mg kg(-1), s.c., 4 h before measurements). Therefore, estrogen-deficiency protects the gastric mucosa by nitric oxide (NO)-mediated mucus hypersecretion.

Vasopressin deficiency decreases the frequency of gastroduodenal ulceration in humans.

Vasopressin is a stress hormone released from the posterior pituitary. In humans suffering from central diabetes insipidus, this release of vasopressin is diminished. It was shown previously that the congenitally vasopressin-deficient Brattleboro homozygous rat is less sensitive to various ulcerogenic stimuli. In this study, we investigated the incidence of gastroduodenal ulceration in vasopressin deficient patients. Data on patients aged 20-70, hospitalized in Hungary between 1992 and 1995 were compared with those on the total population in this age group (6,681,020 in 1994). Subjects with central diabetes insipidus were selected separately (815 cases). Gastroduodenal ulceration was compared in subjects with an intact vasopressin release and vasopressin-deficient patients. The frequencies of gastroduodenal ulceration were also examined separately in male and female subjects. In the total population, the frequency of gastroduodenal ulceration was lower in vasopressin-deficient cases (2.22% versus 0.61%; P < 0.005). Among normal-vasopressin subjects, males have a higher risk of gastroduodenal ulceration than females (3.04% versus 1.46%, respectively; P < 0.001). Among vasopressin-deficient subjects, a similar male:female ratio was observed, but it was not significant (P = 0.36). In comparison to the normal-vasopressin population, the incidence of gastroduodenal ulceration was reduced among vasopressin-deficient males and females by 77% (P < 0.01) and by 82% (P < 0.05), respectively. In conclusion, endogenous vasopressin has a significant harmful action towards the human gastroduodenal mucosa. Peptide and non-peptide vasopressin receptor antagonists might have a potential therapeutic benefit in the treatment (as an adjuvant) and prevention of gastroduodenal ulceration.

[Clinical experience with raloxifene]. / Klinikai tapasztalatok raloxifennel.

Selective receptor modulators (SERMs) are drugs which act via the estrogen receptors and possess tissue specific estrogenic or anti-estrogenic properties. The bone and cardiovascular effects of SERMs are estrogen-like, while they have an effect as estrogen antagonist in the mammary tissues. Raloxifene is the first representative of selective estrogen receptor modulators which does not cause estrogenic effects in the uterus. Based on numerous recently completed controlled clinical trials, the authors characterize the clinical features of raloxifene to assess its therapeutic potency.

Raloxifene, an oestrogen-receptor modulator, prevents decreased constitutive nitric oxide and vasoconstriction in ovariectomized rats.

Administration of graded doses of [Arg(8)]vasopressin (0.06-0.18 microg kg(-1), i.v.) induced a dose-dependent increase in arterial blood pressure in the catecholamine-depleted (phentolamine; 10 mg kg(-1), i.p.) intact and ovariectomized female rat, with the elevation of blood pressure more marked following ovariectomy. In addition, ovariectomy caused the down-regulation of aortic Ca(2+)-dependent constitutive nitric oxide synthase (assessed by the citrulline assay). The down-regulation of the Ca(2+)-dependent constitutive nitric oxide synthase and augmentation of vasopressin-induced blood pressure responses were prevented by the therapy (1 month, p.o.) with the selective oestrogen receptor modulator, raloxifene (0.3-1.0 mg kg(-1) day(-1)), or with 17beta-oestradiol (0.3 mg kg(-1) day(-1)) in ovariectomized rats. Thus, oestrogen deficiency down-regulates vascular constitutive nitric oxide synthase, which appears to be involved in the increased sensitivity of the vasculature to vasopressin, since both effects can be reversed by the exogenous administration of the natural oestrogen 17beta-oestradiol or the selective oestrogen-receptor modulator raloxifene.

In vivo effects of 2-substituted [Mpa1Sar7Arg8]-oxytocin antagonists on postpartum rat.

A set of oxytocin antagonists consisting of [Mpa1Sar7Arg8]-oxytocin substituted by various conformationally restricted or bulky D amino acids at position 2 were synthetized and biologically tested. In in vivo pharmacological investigations, the effects of these peptides were examined on the spontaneous motor activity of postpartum rat. Three of the newly prepared peptides proved at least as effective in inhibiting uterine contractions as clinically investigated atosiban.

Nitric oxide modulates the gastrointestinal plasma extravasation following intraabdominal surgical manipulation in rats.

The actions of nitric oxide (NO) on gastrointestinal plasma loss, assessed by the leakage of [125I]human serum albumin, provoked by intraabdominal surgery and organ manipulation has been investigated in pentobarbitone-anaesthesized rats. Gentle manipulation (3 min) of the stomach or the small intestine following laparotomy leads to an increase in albumin extravasation in the stomach, duodenum, jejunum and colon over 1 h. Administration of the NO synthase inhibitors, N(G)-nitro-L-arginine methyl ester (1-5 mg kg(-1), s.c.) and N(G)-monomethyl-L-arginine (12.5-50 mg kg(-1), s.c.), provoked a further substantial elevation of gastrointestinal albumin extravasation in the surgically manipulated rat, but not in control rats. This effect could be prevented by the pretreatment (15 min) with L-arginine (300 mg kg(-1), s.c.) or by the concurrent infusion of the NO donor, S-nitroso-glutathione (5 microg kg(-1) min(-1), i.v.). Endogenous NO, most likely formed by endothelial NO synthase, thus appears to maintain microvascular integrity during surgery and organ manipulation of the gastrointestinal tract.