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Biomedical subjects

D Prieto

Publications and source records attributed to D Prieto.

At least 19 recordsLinked to original sources
PubMed2002

Contractile response of horse deep dorsal penile vein to histamine.

The present investigation was designed to evaluate the effect of histamine on isolated rings of horse deep dorsal penile vein. Under precontracted or basal conditions, histamine evoked an endothelium-independent contraction. Preincubation of the vein rings with the selective H1 receptor antagonist, mepyramine, shifted the concentration-response curve for histamine and to the H1 receptor agonist 2-pyridylethylamine to the right in a competitive manner. Pretreatment with cimetidine, a specific H2 receptor antagonist, did not modify the pEC50 and maximal contraction of the histamine response. Cimetidine and propranolol failed to induce a change in the relaxation caused by dimaprit, the H2 receptor agonist. Histamine contraction was unaffected by thioperamide, the specific H3 receptor antagonist. (R)-alpha-methylhistamine, the H3 receptor agonist, also induced contractions which persisted in the presence of either thioperamide or tetrodotoxin. These data indicate that horse deep dorsal penile vein shows an endothelium-independent contraction response to histamine, mainly mediated by H1 receptors.

Animals↗
PubMed2001

Surgery for bronchiectasis.

OBJECTIVE: The incidence of bronchiectasis has declined markedly in developed countries. However, a reasonable number of patients still need surgery, despite aggressive physiotherapy and antibiotic therapy. We have reviewed our patients to clarify the benefits from surgery and to analyse the complications. MATERIAL AND METHODS: Between 1988 and 1999, we have operated on 119 patients with bronchiectasis, 71 female and 48 male, with a mean age of 42.2 years (range 11--77 years). Surgery was indicated because of unsuccessful medical therapy in 66 patients (55%), 31 (26%) had haemoptysis, 11 (9.2%) had lung abscess, 10 (8.4%) had lung masses, and three (2.5%) had pneumothorax. The most common manifestations were cough with sputum in 90 patients (76%), haemoptysis in 45 (38%) and recurrent infections in 57 (48%). The mean duration of the symptoms was 4 years (range 1--40 years). The lower lobes were diseased in 61 patients and bilateral disease was found in ten. The mean number of involved pulmonary segments was five (range 1-15). A lobectomy was performed in 75 patients (62%), a segmentectomy in 12 (10%), a pneumonectomy in nine (7.4%) and a bilobectomy in four (3.3%). Complete resection of the disease was achieved in 108 cases (91%). RESULTS: There was no operative mortality and perioperative morbidity occurred in 15 patients (15%), including temporary broncho-pleural fistulae in 7 (5.8%), and post-operative haemorrhage and atrial arrhythmias in four (3.3%) each. After a mean follow-up was 4.5 years, 73 patients (68%) of this group were asymptomatic, and 31 (29%) had meaningful clinical improvement, while only four (3.7%) maintained or worsened prior symptoms. The best clinical improvement occurred in patients with complete resection of the disease (P=0.008). There were no differences in the respiratory function, comparing pre- and post-operative data, with a 2-year of minimum interval. The VC was 91 and 89% and the FEV1 was 83% and 81% of expected, respectively before and after surgery, (P=NS). CONCLUSION: Surgery of pulmonary bronchiectasis has few complications and markedly improves symptoms in the great majority of patients, especially when complete resection of the disease is achieved. Pulmonary resection of bronchiectasis does not alter respiratory function.

Adult↗
PubMed2001

Comparison of balloon dacryocystoplasty to probing as the primary treatment of congenital nasolacrimal duct obstruction.

PURPOSE: In children older than 18 months, primary probing procedures for congenital nasolacrimal duct obstruction (CNLDO) are thought to have lower rates of success. This study compares the results of primary probing to balloon dacryocystoplasty (DCP) in children stratified by age category. METHODS: In a retrospective chart review, 29 eyes with CNLDO that underwent balloon DCP in children older than 18 months were identified and age-matched to 29 eyes that underwent probing. The eyes were divided into 3 age categories: category 1 (18-24 months), category 2 (24-36 months), and category 3 (>36 months). RESULTS: Of the 29 eyes treated with balloon DCP (mean age, 37.1 months), 26 were successfully treated. Twenty-five of the 29 matched probed eyes (mean age, 31.1 months) were successfully treated, resulting in an overall success rate of 90% for balloon DCP and 86% for primary probing. Within each age category, the success rate varied but did not show an advantage to balloon DCP. The presence of crusting and expressible discharge from the puncta during preoperative evaluation predicted a successful probing (OR, 16; 95% CI, 1.3-192). CONCLUSION: Overall, balloon DCP did not appear to present an advantage as compared with primary probing as the initial treatment in these children. Primary probing has an impressive overall success rate that did not diminish in the children older than 36 months.

Catheterization↗
PubMed2001

Determinants of the interval between the onset of symptoms and diagnosis in patients with digestive tract cancers.

The main objective of this cohort study was to analyze the influence of social factors on the interval from the onset of symptoms to diagnosis in the 217 patients with digestive tract cancer. From the clinical charts, the following information was extracted: date of the beginning of illness, dates of medical attendance, type and date of diagnostic tests, characteristics of the disease (symptoms, stage), and date of treatment. From personal interviews we gathered the data not present in the clinical chart: sociodemographic data, information about other underlying diseases, and variables related to lifestyle. The time periods considered were from onset of symptoms to initial consultation (S-C); from initial consultation to hospital admission (C-H); and from hospital admission to diagnosis (H-D). The information on hospital admission, diagnosis, and treatment was prospectively gathered, whereas data before hospitalization were assessed retrospectively. For statistical analysis, we used Kruskal-Wallis test and Cox regression. Pain was the only predictor associated with a shorter S-C period. Hemorrhage, number of symptoms, and hospital consultation significantly shortened the interval C-H. Both hemorrhage and pain, and an initial visit at private primary care were the independent predictors that decreased the period H-D. In conclusion, sociodemographic factors did not influence healthcare attendance.

Aged↗
PubMed2000

Neuropeptide Y regulates intracellular calcium through different signalling pathways linked to a Y(1)-receptor in rat mesenteric small arteries.

Simultaneous measurements of intracellular calcium concentration ([Ca(2+)](i)) and tension were performed to clarify whether the mechanisms which cause the neuropeptide Y (NPY)-elicited contraction and potentiation of noradrenaline contractions, and the NPY inhibition of forskolin responses are linked to a single or different NPY receptor(s) in rat mesenteric small arteries. In resting arteries, NPY moderately elevated [Ca(2+)](i) and tension. These effects were antagonized by the selective Y(1) receptor antagonist, (R)-N(2)-(diphenacetyl)-N-[(4-hydroxyphenyl)methyl]-D-argininea mide (BIBP 3226) (apparent pK(B) values of 8.54+/-0.25 and 8.27+/-0.17, respectively). NPY (0.1 microM) caused a near 3 fold increase in sensitivity to noradrenaline but did not significantly modify the tension-[Ca(2+)](i) relationship for this agonist. BIBP 3226 competitively antagonized the contractile response to NPY in arteries submaximally preconstricted with noradrenaline (pA(2) 7.87+/-0.20). In arteries activated by vasopressin, the adenylyl cyclase activator forskolin (3 microM) induced a maximum relaxation and a return of [Ca(2+)](i) to resting levels. NPY completely inhibited these effects. The contractile responses to NPY in arteries maximally relaxed with either sodium nitroprusside (SNP) or nifedipine were not significantly higher than those evoked by the peptide at resting tension, in contrast to the contractions to NPY in forskolin-relaxed arteries. BIBP 3226 competitively antagonized the contraction to NPY in forskolin-relaxed arteries with a pA(2) of 7.92+/-0.29. Electrical field stimulation (EFS) at 8-32 Hz caused large contractions in arteries relaxed with either forskolin or noradrenaline in the presence of phentolamine. These responses to EFS were inhibited by BIBP 3226. Similar EFS in resting, non-activated arteries did not produce any response. The present results suggest that different intracellular pathways are linked to a single NPY Y(1) receptor in intact rat mesenteric small arteries, and provide little support for involvement of other postjunctional NPY receptors in the contractile responses to NPY. Neurally released NPY also seems to act through Y(1) receptors, and may serve primarily as an inhibitor of vasodilatation.

Animals↗
PubMed2000

Endothelium-independent relaxation induced by histamine in human dorsal penile artery.

1. In vitro preparations of human dorsal penile arteries were used to evaluate the effect of histamine and to characterize the histamine receptors involved in the response. 2. Cumulative administration of histamine induced a concentration-dependent relaxation in precontracted arteries. The H1 receptor agonist 2-pyridylethylamine induced a biphasic response: contraction followed by dilation. The H2 receptor agonist dimaprit produced a marked relaxation. Mepyramine, a histamine H1 receptor antagonist, led to a slight but statistically significant change in the pD2 value corresponding to the relaxant phase of the H1 receptor agonist and the histamine curve. The H2 receptor antagonist cimetidine induced a marked shift in the dimaprit concentration-response curve without affecting the maximum response. Incubation with cimetidine led to a considerable loss in the sensitivity of the arteries to histamine and in the maximum relaxation. Combined treatment with histamine H1 and H2 receptor antagonists resulted in an additional displacement compared with the effect of each antagonist alone on the histamine response. The effects observed using a histamine H3 receptor agonist and antagonist suggest that the involvement of this receptor is unlikely. 3. Removal of the endothelium was unable to reverse the histamine response. Pretreatment with NG-nitro-L-arginine methyl ester, L-arginine and indomethacin had no effect on the histamine control curve. 4. In conclusion, the vasodilation of human dorsal penile artery induced by histamine seems to be mainly mediated by muscular histamine H2 receptors, without the intervention of key intracellular mediators, such nitric oxide or relaxant prostanoids. A minor population of relaxant histamine H1 receptors cannot be excluded.

Adolescent↗
PubMed2000

Applicability of two surgical-site infection risk indices to risk of sepsis in surgical patients.

OBJECTIVE: To compare the ability of the Study of the Efficacy of Nosocomial Infection Control (SENIC) and the National Nosocomial Infection Surveillance (NNIS) indices to predict the development of nosocomial sepsis in subjects undergoing surgery. DESIGN: 1-year prospective case-control study. SETTING: A tertiary-care center in Spain. PATIENTS: Cases were surgical patients with nosocomial sepsis defined using the criteria of the Consensus Conference on Sepsis, identified by daily prospective surveillance. METHODS: Controls were randomly selected from the daily list of surgical inpatients. Data were prospectively collected. To determine whether either index added explanatory information to the other, two methods were used. The first method involved computing a set of residuals for both variables. Residuals and primary variables were introduced in logistic regression models. The second method evaluated both indices with the Goodman-Kruskal (G) nonparametric coefficient. RESULTS: 99 cases and 97 controls were included. After controlling for confounders, both the SENIC index (P<.001) and the NNIS index (P=.04) showed a significant trend. Residuals of the SENIC index added discriminating ability to the NNIS index, whereas residuals of the NNIS index did not improve the prediction ability of the SENIC index. Similar results were yielded by the G statistic: the SENIC index showed higher predictive power than the NNIS index (G=0.56 vs G=0.41). CONCLUSIONS: Both indices performed about equally well for discriminating risk of nosocomial sepsis. The SENIC index had a somewhat better ability than the NNIS index only when the number of discharge diagnoses (not truly a predictive factor) were involved in the calculation of the SENIC index.

Case-Control Studies↗
PubMed1999

Cholinergic modulation of non-adrenergic, non-cholinergic relaxation in isolated, small coronary arteries from lambs.

The presence of cholinergic innervation of small coronary arteries in the lamb was investigated by measuring choline acetyltransferase (ChAT) and acetylcholinesterase (AChE) activities and by performing in vitro experiments in a microvascular myograph to establish whether or not there is a cholinergic component in the response to electrical field stimulation (EFS). ChAT-specific activity was present in proximal coronary segments, but was significantly higher in small coronary arteries. AChE-positive ganglia and fibres were distributed within the adventitia and outer third of the media in proximal coronary segments, and dense perivascular nerve plexuses were observed in small coronary arteries. Acetylcholine induced contractions in all preparations examined and relaxations in 20% of the segments contracted with the thromboxane analogue U46619. EFS did not induce neurogenic contractions in lamb small coronary arteries. In the presence of the alpha-adrenoceptor antagonist, phentolamine, EFS caused frequency-dependent reproducible relaxations that were enhanced by the blocker of cholinergic transmission, botulinum neurotoxin. An inhibitor of AChE, physostigmine, had no significant effect on the relaxations caused by EFS, while both the muscarinic receptor antagonist, atropine, and the muscarinic M2-receptor antagonist, AFDX 116, enhanced these responses. Blockade of sympathetic neurotransmission with guanethidine or incubation with the P2-receptor antagonist, suramin, abolished the relaxations induced by EFS, whereas propranolol was without effect. Low-frequency EFS caused less relaxation in preparations activated by acetylcholine than in those contracted with U46619, while sensitivity and maximal relaxation induced by adenosine 5'-triphosphate (ATP) were not different in U46619- and acetylcholine-contracted arteries. The presence of the enzymes necessary for both biosynthesis and degradation of acetylcholine and the finding that blockers of cholinergic neurotransmission enhance EFS-induced relaxations suggest that small coronary arteries are cholinergically innervated.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1999

Differences between men and women as regards the effects of protein-energy malnutrition on the hypothalamic-pituitary-gonadal axis.

Although protein-energy malnutrition (PEM) affects 50% of hospitalized patients, its effects on the hypothalamic-pituitary-gonadal (HPG) axis have not been extensively investigated. To investigate the effects of PEM on the HPG axis in hospitalized patients, 62 inpatients ages 18-91 y (35 men and 27 women) had a nutritional and hormonal evaluation. Hormones were determined in blood samples obtained between 0700 and 1200 h. Patients were divided into two subgroups: those with body mass index (BMI) <18.5 kg/m2 (low body mass index [LBMI]; 16 men, 13 women) and those with BMI >20 kg/m2 (normal-high body mass index [NHBMI]; 19 men, 14 women). The nutritional parameters of LBMI patients were inferior to those of NHBMI patients. Total and free testosterone levels were subnormal, 31.4% and 17.2% respectively, in all men; free testosterone was subnormal in 31.25% of LBMI versus 5.3% of NHBMI male patients and total testosterone concentration was subnormal in 43.8% of LBMI versus 21.1% of NHBMI male patients. Luteinizing hormone (LH) level was higher in LBMI men than in NHBMI men, whereas the reverse was the case for women, for whom follicle-stimulating hormone (FSH) also was lower in the LBMI group than the NHBMI group. The HPG axis hormones which best discriminated between the LBMI and NHBMI groups were free testosterone for men and LH and FSH for women, which were all lower in the LBMI than in the NHBMI group. LH was correlated with BMI and midupper arm muscle circumference (AMC) (women positively and men negatively) but not with triceps skin-fold thickness (TSF). Total testosterone level was positively correlated with AMC and free testosterone with TSF. Hypogonadism is common among hospitalized patients with PEM. Men with PEM have low testosterone levels with normal or high gonadotropin levels, which suggests impairment of Leydig cell function. Women with PEM suffer hypogonadotropic hypogonadism. AMC correlates positively with total serum testosterone concentration in men and with LH levels in women, suggesting that satisfactory function of the HPG axis requires a functional (protein) reserve as well as an energy (fat) reserve.

Adult↗
PubMed1999

Excision of pulmonary metastases of osteogenic sarcoma of the limbs.

OBJECTIVE: The combination of surgery and chemotherapy improves the prognosis of patients with osteogenic sarcoma of the limbs without detectable metastases at presentation. However, lung metastases are a frequent complication. To evaluate the role of the resection of pulmonary metastases of osteogenic sarcoma of the limbs, we have reviewed our experience with this type of surgery, combined with a multidrug chemotherapy protocol. PATIENTS AND METHODS: From January 89 to December 97, 198 patients operated on for osteogenic sarcomas of the limbs were followed in our centre. Of these, 31 patients (15.7%), with a mean age of 25 years (range 10-54 years), developed lung metastases and had undergone 45 thoracotomies. All patients received chemotherapy, followed by resection of metastatic lesions and additional chemotherapy. The mean time interval between resection of the primary tumour and the diagnosis of lung metastases was 22 months (4-122 months). Eight patients (25.8%) needed more than one (2-4) thoracotomy. The mean time interval between the first and second thoracic surgeries was 9.2 months (2-14 months). RESULTS: There was no operative mortality or major morbidity. During the 45 thoracotomies, five lobectomies and 40 wedge resections were necessary. The mean number of metastases resected per thoracotomy was 3.4 (range 1-10). The degree of necrosis was evaluated by seriated sections for a histologic study. In the end the mean necrotic volume was calculated. A strong correlation was found between the degree of necrosis of the metastases and the need for reoperation for new metastatic lesions, because all the patients who needed more than one operation had less than 80% of necrosis of metastases. The patients were followed for a mean period of 28 months (6-72 months). Ten patients (32.2%) died of related causes at a mean of 19.4 months after thoracic surgery, three of whom had more than one operation. The 3-year survival after metastasectomy was 61%. Patients without pulmonary metastases had a 3-year survival of 79%. CONCLUSIONS: In patients with lung metastases of an osteogenic sarcoma, the combination of chemotherapy and surgery improves the outcome. In our series the mortality was not influenced by the number or thoracotomies required.

Adolescent↗
PubMed1999

Risk factors for monoinfections and coinfections with HIV, hepatitis B and hepatitis C viruses in northern Spanish prisoners.

A cross-sectional study was conducted in prisons of Cantabria (northern Spain) from June 1992 to December 1994. Inmates were asked to participate in a survey on prevalence and risk factors for monoinfections and coinfections with HIV, HBV and HCV. Crude and multiple odds ratios of risk factors were calculated (by polychotomous logistic regression). Prevalence of coinfections was higher than that of monoinfections. IDU risk factors were the main independent variables associated with monoinfections and coinfections with these agents. The strength of association increased with the degree of coinfection for IDU risk factors and penal status, e.g. duration of injecting drug use for more than 5 years yielded an adjusted OR ranging from 1.3 (95% CI: 0.4-5.1) for HBV monoinfection to 180 (95% CI: 61.0-540.0) for HIV-HBV-HCV coinfection. In comparison, sexual behaviours were less important than IDU risk factors.

Adult↗
PubMed1999

Coinfections by HIV, hepatitis B and hepatitis C in imprisoned injecting drug users.

In order to know the prevalence and risk factors for coinfections by human immunodeficiency virus (HIV), hepatitis B virus (HBV) and hepatitis C virus (HCV) among injecting drug users (IDUs), a cross-sectional study was carried out in two prisons of the province of Cantabria, northern Spain. Three hundred and sixty-two IDU inmates were recruited. All inmates were interviewed and their blood tested for HIV, HBV and HCV. Crude and multiple risk factor adjusted for (by polychotomous logistic regression) odds ratios were calculated. Prevalence of HBV-HCV coinfection (42.5%) was higher than HIV-HBV-HCV coinfection (37.3%), whereas monoinfections were very uncommon (overall: 13%). Long-term injectors and reincarceration were the foremost risk factors for both coinfections, showing a trend between the degree of association and the number of viruses infecting a patient. No significant relationship between coinfection status and sexual practices was observed. The results related to coinfections are consistent with previous studies of prevalence and risk factors for HIV, HBV and HCV, in indicating that the high rates of coinfections among IDU inmates emphasise the need to harm-reduction policy across prisons in Spain.

Adult↗
PubMed1999

Cycling of human dendritic cell effector phenotypes in response to TNF-alpha: modification of the current 'maturation' paradigm and implications for in vivo immunoregulation.

Dendritic cells (DCs) are potent antigen presenting cells reported to undergo irreversible functional 'maturation' in response to inflammatory signals such as TNF-alpha. The current paradigm holds that this DC maturation event is required for full functional capacity and represents terminal differentiation of this cell type, culminating in apoptotic cell death. This provides a possible mechanism for avoiding dysregulated immunostimulatory activity, but imposes constraints on the capacity of DCs to influence subsequent immune responses and to participate in immunological memory. We report that the cell surface and functional effects induced by TNF-alpha are reversible and reinducible. These effects are accompanied by a concordant modulation of cytokine mRNA expression that includes the induction of proinflammatory factors (IL-15, IL-12, LT-alpha, LT-beta, TNF-alpha, RANTES) which is coincident with the down-regulation of counter-regulatory cytokines (IL-10, TGF-beta1, TGF-beta2, IL-1 RA, MCP-1). The resultant net effect is a dendritic cell activation state characterized by a transient proinflammatory posture. These results demonstrate that 1) human DCs do not undergo terminal 'maturation' in response to TNF-alpha, 2) DC phenotypes are more pleiotropic than previously thought, and 3) DCs are potential immunoregulatory effector cells with implications for control of immune responses in both in vivo and in vitro systems.

Antigens, CD↗
PubMed1999

[Mortality due to multiple sclerosis in Spain, 1951-1992].

UNLABELLED: FOUNDATIONS: In this work, multiple sclerosis mortality trend in Spain from 1951 to 1992 is displayed. The purpose is to identify the pattern of age-adjusted mortality evolution and to measure the effect of environmental factors. METHODS: Multiple sclerosis mortality is standardized by age using the world standard population. In each year from 1951 to 1992, age-specific mortality rates are transversely fitted to the Gompertz law. The Longitudinal Gompertzian analysis is applied to the obtained coefficients to quantify the effects of competing risks and environmental factors. RESULTS: Multiple sclerosis age-adjusted mortality increased from 1951 to 1968; a step-down is produced in 1969 (coinciding with change from 7th to 8th revision of the International Classification of Diseases) and a stability from 1970 on. Multiple sclerosis in Spain is a Gompertzian disease. Adjusting mortality for R0 (which in the Gompertz function represents the addition of the environmental factors acting in a point near the beginning of the life and the competing risks of death) the result was almost constant throughout the whole analyzed period. CONCLUSIONS: It is suggested that multiple sclerosis mortality trend in Spain is due to changes in some environmental factor acting early and in a point; on the other hand, diet or other environmental factors acting for long time or genetic factors have and little or no influence in this trend.

Adult↗
PubMed1999

Aortic valve replacement with small-sized disc prostheses (medtronic hall).

BACKGROUND AND AIM OF THE STUDY: Several studies have demonstrated a worse performance of small prostheses in the narrow aortic root. However, modern low-profile mechanical prostheses have improved hemodynamic performance, are easy to implant, and have been used increasingly in elderly patients, where narrow roots are most frequently observed. We describe our experience in patients with aortic annuli >21 mm with the use of Medtronic Hall prostheses. METHODS: Between April 1988 and December 1997, a total of 332 patients (218 females, 114 males; mean age 59.3 +/- 9.8 years (range: 29-75 years) received Medtronic Hall size 20 (n = 140), 21 (n = 96) or 22 (n = 96) prostheses. The mean body surface area was 1.59 +/-0.12 m2 (range: 1.27-2.01 m2); 140 patients were in NYHA functional classes III/IV. There were no significant differences in clinical characteristics of patients in the three prosthesis-size groups. RESULTS: The mean preoperative systolic left ventricular/aorta gradient was 64.5 +/- 24.8 mmHg (no significant inter-group difference). After cardiopulmonary bypass, peak gradients through the aortic prostheses were 13.9 +/- 8.0 mmHg in size 20 valves, 14.0 +/- 8.1 mmHg in size 21, and 10.1 +/- 8.9 mmHg in size 22. Four patients died in hospital (mortality rate 1.2%); there were no significant inter-group differences in hospital morbidity. Follow up was complete for 97% of the patients (mean 4.3 years; range: 1-11 years). The late mortality rate was 9.3% (n = 31; 2.56% per pt-yr); of these patients, 20 (14.3%) had size 20 prostheses, seven (7.3%) size 21, and four (4.2%) size 22 (p = 0.01). Fourteen patients (4.2%) died from cardiac causes, and six (1.8%) from prosthesis-related causes. Preoperative older age and aortic regurgitation were the only independent predictors of late mortality. Eight patients had systemic thromboembolic events (0.66% per pt-yr), two had prosthetic thrombosis (0.17% per pt-yr) and five had hemorrhagic episodes (0.41% per pt-yr). Seven patients had prosthetic valve endocarditis (0.58% per pt-yr). Among survivors, 97% are currently in NYHA class I/II. CONCLUSIONS: The small (size 20, 21 and 22) Medtronic Hall prostheses have good hemodynamic performance and are an excellent option as valve substitutes in patients with narrow aortic roots.

Adult↗
PubMed1998

Characterization of NPY receptors mediating contraction in rat intramyocardial coronary arteries.

In vitro experiments in a microvascular myograph were designed in order to characterize the receptor subtypes and the mechanisms underlying the contractions induced by neuropeptide Y (NPY) in rat coronary small arteries. The rank order of potency for NPY-receptor agonist-induced increases in tension in endothelium-intact preparations was polypeptide Y (PYY)> NPY > or = [Leu31Pro34]NPY, while NPY(13-36) only induced small contractions at the highest concentration applied. The selective neuropeptide Y1 receptor antagonist, BIBP 3226, caused rightward shifts in the concentration-response curves for NPY and the slope of the Schild plot was not significantly different from unity. The pA2 value for BIBP 3226 against NPY was 7.88+/-0.15 (n = 6). We have earlier shown that endothelial cell removal does not change the contractile responses induced by NPY, but indomethacin (3 x 10(-6) M) significantly reduced the contractions induced by the peptide. In contrast, the thromboxane receptor antagonist, SQ29548, which abolished the contractions induced by the thromboxane analogue, U46619, did not change the concentration-response curves for NPY. In conclusion, the present study suggests that Y1 receptors mediate NPY-induced contractions in rat coronary resistance arteries, and that a non-thromboxane prostanoid is involved in the contractile mechanism.

Animals↗
PubMed1998

Nitrergic relaxation of the horse corpus cavernosum. Role of cGMP.

The involvement of nitric oxide (NO) and the mechanisms mediating neurogenic relaxation were investigated in the horse corpus cavernosum. NADPH-diaphorase activity was expressed in nerve fibres around arteries and muscular bundles in the horse trabecular tissue. Relaxations in response to electrical field stimulation were tetrodotoxin (10(-6) M)-sensitive, indicating their neurogenic origin. The NO synthase inhibitor, L-NO-arginine (L-NO-Arg, 3 x 10(-5) M), abolished the electrically induced relaxations, which were significantly reversed by L-arginine (3 x 10(-3) M). Exogenous NO (10(-6)-10(-3) M) evoked relaxations which were unaffected by L-NO-Arg. 1H-[1,2,4]oxadiazolo[4,3,-a]quinoxalin-1-one (ODQ, 5 x 10(-6) M), an inhibitor of guanylate cyclase activation by NO, reduced the relaxations in response to electrical stimulation and exogenous NO. Iberiotoxin (3 x 10(-8) M) or apamin (5 x 10(-7) M), inhibitors of large and small conductance Ca2+-activated K+ channels, respectively, and glibenclamide (3 x 10(-6) M), a blocker of ATP-sensitive K+ channels, failed to modify the relaxations with NO. It is suggested that NO is present in nerve fibres of the horse corpus cavernosum and relaxes smooth muscle through a guanylate cyclase-dependent mechanism. Neither Ca2+-activated nor ATP-sensitive K+ channels seem to be involved in these relaxations.

Adenosine Triphosphate↗