[Are the patients not carrying protections after radical prostatectomy really continent?]. / Les patients ne portant pas de protection après prostatectomie radicale sont-ils vraiment continents?

AIM: To analyse urinary continence and related quality of life in patients not wearing any pad after robotic assisted radical prostatectomy (RARP). METHOD: Two hundred and sixteen patients operated consecutively by RARP between January 2009 and June 2011 were evaluated by the ICS (International Continence Society) Male Self-questionnaire. The questionnaires were sent by mail and mailed back by patients with a minimum of 14 months following surgery. The ICS questionnaire contains a symptom score (ICS 1) and a quality of life score (ICS 2). RESULTS: Out of 216 sent questionnaires, 145 (67%) were received. The subgroup of 121 patients who replied that they were not wearing any pad was analysed. Fifty-three (43,8%) of them reported not having leakage when coughing or sneezing, 65 (53,7%) reported not having spontaneous leakage, and 102 (84,3%) reported not having leakage when sleeping. The ICS 1 and ICS 2 scores were strongly correlated (Pearson correlation coefficient 0.96). CONCLUSION: Within a group of patients not wearing any pad following RARP, the continence as assessed by self-questionnaires remains altered. This analysis might help counselling patients who are about to choose a surgical treatment for their prostate cancer.

[Is nocturnal polyuria more frequent among patients with Parkinson's disease?]. / La polyurie nocturne est-elle plus fréquente chez les patients parkinsoniens?

OBJECTIVE: Nocturia is a frequent complaint in the population of idiopathic Parkinson's disease patients (IPD). The consequences of nocturia in the IPD population are at high importance as these patients have motor problems and therefore a risk of nocturnal fall. The aim of the study was to determine the mechanism of nocturia in patients with MPI, by determining the prevalence of nocturnal polyuria (NP) in this population. METHOD: A prospective study by bladder diary was conducted on 70 consecutive IPD patients consulting for regular neurological follow-up at a non-severe stage. Nocturia was defined as 1 or more awakenings to urinate. Two definitions of NP were used: nocturnal diuresis 33% or higher of the total diuresis (NUV33), which is the ICS (International Continence Society) definition, and nocturnal diuresis 90 mL/h or higher (NUP90). RESULTS: The mean patient age was 71 years (45-86, sex ratio 33/30). On average, patients were diagnosed for IPD 6.76 years earlier. The prevalence of NP was 64.5% according to NUV33 definition, and 17.7% according to NUP90 definition. Among patients with nocturia, the prevalence of NP was 66% (NUV33) and 21.5% (NUP90). No association was observed between disease duration of the IPD and the prevalence of nocturia and NP. Patients 70 years and older were more likely to have NP as defined by NUV33 than those less than 70 years (72.7% versus 55.17%, P=0.015). Men had more frequently nocturia (33.3% versus 20.7%, P=0.027). CONCLUSIONS: The prevalence of NP and nocturia was analyzed in patients with IPD at a non-severe stage. This prevalence was not higher than in the general population of the same age. The mechanism of nocturia in patients with IPD is not unambiguous and therefore requires to be explored by a bladder diary.

[Magnetic resonance imaging for delineation of prostate in radiotherapy: monocentric experience and review of literature]. / Imagerie par résonance magnétique et délinéation de la prostate en radiothérapie : expérience monocentrique et revue de la littérature.

PURPOSE: To assess the benefits of magnetic resonance imaging (MRI) in the dosimetric treatment planning for prostate radiotherapy. PATIENTS AND METHODS: Ten consecutive patients have been enrolled. They were treated for a low risk prostate adenocarcinoma. A rigid superimposition was performed between MRI and scan slides obtained at time of virtual simulation, then prostate volume was delineated by four to five physicians, on TDM slides and on MRI/TDM superimposition. For each treatment plan, we assessed the impact of MRI in terms of planned treatment volume (PTV) position, individual variability of prostate delineation and doses delivered to the critical organs. The prescribed dose was 74 Gy in 37 fractions to the PTV. RESULTS: PTV delineated on TDM (V(TDM)) were 1.15 (SD 3.71) larger than volumes delineated on MRI. Prostate apex was 4.6 mm (SD 2.87) lower on TDM than on MRI. Posterior limit of the prostate was in mean 4 mm more posterior on TDM. The variability between physicians in terms of prostate delineation was lower using MRI. For apex, these variations were 6.8 mm using TDM, versus 3.3 mm using MRI. Mean rectal dose was 8 % lower with MRI, compared to delineation using TDM. CONCLUSION: Superimposition TDM/MRI improves accuracy, decreases delineation variability, and allows to spare anterior part of the rectum from irradiation. It remains unknown whether this strategy translates into clinical benefit.

[Management of patients with long term indwelling catheter: Survey of Limousin general practitioners]. / Prise en charge des patients avec sonde vesicale à demeure au long cours : enquête auprès des médecins généralistes du Limousin.

OBJECTIVE: To evaluate the management of patients with long-term (>1 month) indwelling catheter by general practitioners (GP). PATIENTS AND METHODS: A self-questionnaire was sent to 603 regional GP, between March and May 2010. It was composed of 12 multiple-choice questions and one open question, about management of their patients with indwelling catheter. RESULTS: Two hundred and twenty-eight self-questionnaires were analyzed: 126 (55%) from urban GP and 102 (45%) from rural GP. On average, each GP managed 1.3 patients with long term indwelling catheter (>1 month). The catheters were changed by the GP, urologists, and nurses in 23.2, 23.7, and 53.1%, respectively. In a majority of cases, catheters were changed every 4 weeks (59%). Nursing cares were prescribed by 64.5% of GP. Prescribed drainage bags were sterile in 42.5%. Most of GP reported to prescribe a daily change of drainage bag (56.1%). Urine analysis as performed only in case of symptomatic urine infection by 58% of respondents. Fifty percent of GP required guidelines for the management of patients with long term indwelling catheter. Rural GP managed significantly more patients with indwelling catheter, prescribed fewer sterile drainage bags, made change the drainage bag less often, and required the help of urologist less frequently. CONCLUSION: Management of long term indwelling catheter was heterogeneous among GP, and varied according to rural or urban practice. Some used significantly differed from available practice guidelines. This survey could be a basis for the preparation of an informative document aimed at GP.

[Preoperative factors of misdiagnosis of renal angiomyolipoma]. / Facteurs associés à l'échec du diagnostic préopératoire des angiomyolipomes rénaux.

OBJECTIVES: To explain the high incidence of misdiagnosis of angiomyolipoma (AML) prior to surgery. MATERIALS AND METHODS: Between 1989 and 2007, 2,657 patients were operated for a renal tumor at Dupuytren hospital in Limoges and at Cochin hospital in Paris. In 85 cases (3.2%), tumors were AMLs on pathology. The group of patients in which the diagnosis was done preoperatively was compared to the one in which the diagnosis was missed. RESULTS: Mean age of patients was 57-years-old and the sex-ratio was five women for one man. The mean size of AMLs was 5.4 cm. The patients were symptomatic in 46% of cases (39/85). The diagnosis of AML was ignored preoperatively in 62 patients (73%). In multivariate analysis, the small size of the AML, low proportion of fat and male sex were significantly associated with misdiagnosis of AML (p<0.001, p<0.018 and p<0.008, respectively). CONCLUSIONS: The incidence of misdiagnosis of AML preoperatively is high. The diagnosis seems particularly difficult when the tumor is small or contains a small proportion of fat. In addition, this study highlights that the diagnosis of AML is frequently ignored in men. The increased resolution of CTscan and the use of preoperative biopsies for tumors less than 4 cm could be helpful to decrease the incidence of useless surgery of AMLs.

[Study of urinary continence after radical prostatectomy. Comparison between laparoscopic and retropubic prostatectomy based on a series of 251 cases]. / Etude de la continence urinaire après prostatectomie radicale. Comparaison entre prostatectomie rétropubienne et coelioscopique à propos de 251 cas.

INTRODUCTION: The objective of this study was to compare the results in terms of continence and quality of life between retropubic radical prostatectomy and laparoscopic radical prostatectomy, performed according to the same principle of retrograde dissection from the apex. MATERIAL AND METHOD: The series was composed of 120 patients undergoing retropubic radical prostatectomy and 131 patients undergoing laparoscopic radical prostatectomy performed in the Limoges hospital, urology and andrology department, between January 2002 and September 2005. Continence was evaluated by anonymous self-administered questionnaire sent to the patient's home. Pain was evaluated by visual analogue scale and narcotic consumption. Predictive factors of continence were analysed. RESULTS: The two groups were comparable in terms of pathological stage, Gleason score and age. The laparoscopy group comprised more patients with a history of transurethral resection of the prostate and more obese patients. No significant difference was observed between laparoscopy and laparotomy for degree of continence (71% versus 76%; p>0.05), time to return of continence (13 weeks versus nine weeks; p>0.05) and rate of mild (14% versus 13%), moderate (7% versus 6%) and severe (7% versus 5%) urinary incontinence. The anastomosis secondary stenosis rate was also identical in the two groups. Age was found to be a predictive factor for continence, especially for the mean time to return periods of continence. The patient's weight, prostate weight and TNM stage were not predictive factors for incontinence. The incontinence rate was 40% for salvage prostatectomies after radiotherapy. The mean duration of bladder catheterization was 6.9 days in the laparoscopy group and 7.2 days in the laparotomy group. Narcotic consumption was significantly lower in the laparoscopy group (21 mg versus 36 mg; p<0.05). CONCLUSION: Laparoscopic radical prostatectomy appears to give the same results in terms of continence as retropubic radical prostatectomy. However, these procedures were the first laparoscopic prostatectomies performed in the department, suggesting that, with greater experience, the results of laparoscopy could become superior to those of laparotomy. The laparoscopic technique also appeared to provide better patient comfort by decreasing postoperative pain.

Limitation of exercise capacity in nucleoside-treated HIV-infected patients with hyperlactataemia.

BACKGROUND: Inhibition of DNA polymerase gamma by nucleoside reverse transcriptase inhibitors (NRTIs) can cause mitochondrial dysfunction and cellular toxicity. Hyperlactataemia, which is a consequence of a shift in the metabolism of pyruvate, is an indicator of nucleoside-related mitochondrial toxicity. METHODS: We evaluated exercise and oxidative capacities as well as circulatory and ventilatory responses to exercise in 24 HIV-infected patients on NRTIs presenting hyperlactataemia [mean (+/-standard deviation) fasted lactate=3.5+/-1.1 mmol/L]; 27 NRTI-treated patients with normal baseline lactate concentrations were used as controls (mean fasted lactate=1.6+/-0.3 mmol/L). RESULTS: In the patients with hyperlactataemia, the average peak work capacity (1.7+/-0.6 W/kg) and peak oxygen consumption (VO(2)) (21+/-4 mL/kg/min) were significantly lower (P<0.01) than in control subjects (work, 2.1+/-0.4 W/kg; VO(2), 25+/-4 mL/kg/min). The capacity to increase oxygen extraction during exercise was significantly diminished in the hyperlactataemia group, as shown by a low peak systemic arteriovenous oxygen difference (a-vO(2)) difference compared with controls (11+/-3 vs 14+/-3 mL/dL; P=0.008), and as indicated by a linear correlation between VO(2) and systemic a-vO(2) difference (r(2)=0.76). During exercise, the increases in cardiac output relative to VO(2) (mean Delta cardiac output (Q)/DeltaVO(2)=8+/-3.6) and ventilation (mean Delta ventilation (VE)/DeltaVO(2)=48.6+/-13.2) were significantly higher in hyperlactataemia patients compared with controls (mean cardiac output Delta(Q)/DeltaVO(2)=6+/-2; mean DeltaVE/DeltaVO(2)=42+/-12.7; P=0.03). CONCLUSIONS: The degree of exercise limitation in patients with nucleoside-related mitochondrial toxicity correlates directly with the severity of impaired muscle oxidative phosphorylation, as indicated by the capacity for muscle oxygen extraction. Exaggerated circulatory and ventilatory responses to exercise are direct consequences of the level of impaired muscle oxidative phosphorylation.

Hypoxic vasoconstriction of rat main pulmonary artery: role of endogenous nitric oxide, potassium channels, and phosphodiesterase inhibition.

This study investigated the influence of NO, potassium (K+) channel blockade, and the phosphodiesterase inhibitors (PDEIs) theophylline (non-selective PDEI), siguazodan (PDE3I), rolipram (PDE4I), and zaprinast (PDE5I) on rat isolated main pulmonary artery hypoxic (95% N2 and 5% CO2) vasoconstriction. Hypoxic vasoconstriction increased by 27% (p < 0.01) in the presence of the NO synthase inhibitor L-NAME (10(-4) M), and by 15% (p < 0.05) in the presence of the K(ATP) channel blocker glibenclamide (10(-6) M), without potentiation by the combination of these two drugs. Hypoxic vasoconstriction decreased by 28% (p < 0.01) in presence of the Kv,-voltage-dependent channel blocker 4-aminopyridine (10(-3) M), whereas the other K+ channel blockers, charybdotoxin (BKCa, large-conductance Ca2+-sensitive K+ channels) and apamin (SKCa, small-conductance Ca2+-sensitive K+ channels) had no effect. The nonselective PDEI theophylline induced a concentration-dependent relaxation (pD2 = 4.05, Emax = 90% [expressed as a percentage of maximal relaxation induced by papaverine 10(-4) M]). Among the selective PDEIs, siguazodan was significantly (p < 0.01) more efficient than rolipram and zaprinast (Emax values were 84%, 67%, and 58%, respectively) and significantly (p < 0.05) more potent than zaprinast (pD2 values were 6.48, 6.34, and 6.16 for siguazodan, rolipram, and zaprinast). Glibenclamide and L-NAME significantly (p < 0.05) shifted the concentration-response curve (CRC) for zaprinast to the right, and L-NAME shifted the CRC significantly to the right for siguazodan. In the presence of L-NAME, glibenclamide had no effect on the CRC of zaprinast. We conclude that (a) NO exerts a permanent inhibitory effect against hypoxic vasoconstriction that might be mediated in part by an activation of K(ATP) channels; (b) a 4-aminopyridine-sensitive K+ channel is involved in vasoconstriction under hypoxic conditions; (c) PDEs 3 and 5 are the predominant PDE isoforms in rat pulmonary artery relaxation; and (d) NO and K(ATP), but neither BK(Ca), SK(Ca), nor Kv channels, are involved in the relaxant effect of PDEIs.

Physical impairments in cervicogenic headache: traumatic vs. nontraumatic onset.

In order to quantify the physical impairments associated with different types of headache, 77 subjects belonging to four different groups (postmotor vehicle accident cervicogenic headache subjects, cervicogenic headache subjects nontraumatic, migraine patients and control subjects) were evaluated using the following variables: posture, cervical range of motion, strength of the neck flexors and extensors, endurance of the short neck flexors, manual segmental mobility, proprioception of the neck, and pain (McGill Pain Questionnaire and the skin roll test). The results of this study showed that postmotor vehicle accident cervicogenic patients have significantly limited active cervical range of motion (in flexion/extension and rotations), present decreased strength and endurance of neck flexors and decreased strength of the extensor muscles. Our results suggest that there are enough differences between the postmotor vehicle accident and nontraumatic cervicogenic headache subjects to warrant caution when analysing the data of these two subgroups together, as several studies have done in the past. The onset of headache is therefore an important variable that should be controlled for when attempting to characterize the physical impairments associated with cervicogenic headache.

[Splenic lobulation and pseudo-cancer of the left kidney]. / Lobulation splénique et pseudo-cancer du rein gauche.

Discovery of a mass in the spleno-reno-pancreatic region requires complementary investigations to exclude a false diagnosis of renal tumour. While resembling a renal tumour, such masses can actually correspond to splenic lobulation, a cyst of the tail of the pancreas or a splenic entity (accessory spleen or splenosis).

[Penile lichen sclerosus: follow-up study]. / Lichen scléreux génital masculin: étude de suivi.

INTRODUCTION: The aim of this work was to study the long-term course of patients with penile lichen sclerosus and atrophicus. PATIENTS AND METHODS: We reviewed the files of 16 patients followed at our university center from 1982 to 1997 for pathologically proven penile lichen sclerosus and atrophicus. Age at disease onset, duration of the disease course, presence of a triggering factor, initial localization, signs and symptoms, treatment given and its efficacy were recorded. RESULTS: Mean age at diagnosis was 52 years. Inaugural prepuce localizations were observed in 6 cases, involving the distal part of the penis and the glan in 3 cases. Concomitant involvement of the glan and the balanopreputial groove were seen in 6 cases. The localization was limited to the glan in one case. Six patients underwent posthectomy and one had dorsal plasty of the prepuce. The 9 other patients were treated medically with topical corticosteroids and/or androgens. One patient had died prior to evaluation. Among the 9 patients given medical treatment, lichen sclerosus persisted in 7, one developed a squamous cell carcinoma of the penis and one was cured. Among the 6 cases of surgical treatment, 5 were cured and 1 had persistent lesions. Considering the initial localization, long-term course showed that 7 of the 8 patients with a prepuce localization (alone or in association with glan involvement) were cured while the 7 patients with a lesion of the balanopreputial groove (alone or in association with glan involvement) or a lesion of the glan alone still had lichen sclerosus and atrophicus. The non parametric Fischer test showed that the chances of cure were better for preputial localizations than for balanopreputial localizations (p = 0.001) and that surgical treatment was more effective than medical treatment. DISCUSSION: This study of a small number of patients highlighted two points: prepuce localizations of lichen sclerosus and atrophicus cure better than balanopreputial localizations, and that medical treatment is partially effective in balanopreputial localizations. One patient developed squamous cell carcinoma of the penis. As the level of the cancer risk remains unknown, it would be important to provide the most effective treatment in all cases of penis lichen sclerosus and atrophicus.

Hypoxic pulmonary vasoconstriction.

Hypoxic vasoconstriction is unique to pulmonary circulation. The pulmonary response is part of a self-regulatory mechanism by which pulmonary capillary blood flow is automatically adjusted to alveolar ventilation for maintaining the optimal balance of ventilation and perfusion. In pathological conditions, hypoxic pulmonary vasoconstriction may occur as an acute episode or as a sustained response with pulmonary hypertension and vascular remodeling. Vasoactive substances produced from the endothelial cells (prostanoids, nitric oxide, or endothelin) or other mediators such as 5 hydroxytryptamine have been examined as possible mediators of hypoxic vasoconstriction. These appear more likely to be modulators than mediators of the vasoconstrictor response to hypoxia. Recent hypotheses have emerged indicating that O2 levels per se can regulate ion channel activity. The modulation of both K+ and Ca2+ channels differs according to the conduit or resistance pulmonary vessel type, tending to extend the former and contract the latter, thereby opposing the ventilation to perfusion mismatching. In the absence of drugs that act selectively on pulmonary circulation, inhaled therapy is an alternative in the treatment of pulmonary hypertension. According to its short half-life and to its potential cytotoxicity, nitric oxide is only of value in the management of patients with acute respiratory disease. Aerosolized prostacyclin and iloprost result in a sustained efficacy of the inhaled vasodilator regimen in patients with severe pulmonary hypertension and offer a new strategy for treatment of this disease. At the moment, therapy aimed at reversing the structural remodeling and matrix deposition in pulmonary arteries remains experimental. New drugs such as potassium channel openers or endothelin receptor antagonists warrant further investigations as possible therapeutic candidates in the treatment of pulmonary hypertension.

Role of potassium channels and nitric oxide in the relaxant effects elicited by beta-adrenoceptor agonists on hypoxic vasoconstriction in the isolated perfused lung of the rat.

1. The aims of this study were to compare, in the rat isolated perfused lung preparation, the antagonist effects of a nonselective beta-adrenoceptor agonist (isoprenaline), a selective beta2-adrenoceptor agonist (salbutamol) and a selective beta3-adrenoceptor agonist (SR 59104A) on the hypoxic pulmonary pressure response, and to investigate the role of K+ channels, endothelium derived relaxing factor and prostaglandins in these effects. K+ channels were inhibited by glibenclamide, charybdotoxin or apamin, NO synthase and cyclo-oxygenase were inhibited by N(G)-nitro-L-arginine methyl ester (L-NAME) and indomethacin, respectively. 2. Hypoxic ventilation produced a significant increase in perfusion pressure (+65%, P<0.001) and L-NAME significantly increased this response further (+123%, P<0.01). After apamin, L-NAME, indomethacin, post-hypoxic basal pressure did not return to baseline values (P<0.001). 3. Glibenclamide partially inhibited the relaxant effects of isoprenaline (P<0.05) and salbutamol (P<0.001) but not that of SR 59104A. In contrast, charybdotoxin and apamin partially inhibited the relaxant effects of SR 59104A (P=0.053 and <0.01, respectively) but did not modify the effects of isoprenaline and salbutamol. L-NAME partially inhibited the dilator response of salbutamol (P<0.01) and SR 59104A (P<0.05) but not that of isoprenaline. 4. We conclude that (a) EDRF exerts a significant inhibition of the hypoxic pulmonary response, (b) SK(Ca) channel activation, EDRF and prostaglandins contribute to the reversal of the hypoxic pressure response, (c) the vasodilation induced by isoprenaline is mediated in part by activation of K(ATP) channels, that of salbutamol by activation of K(ATP) channels and EDRF. In contrast, SR 59104A partly operates through BK(Ca), SK(Ca), channels and EDRF activation, differing in this from the beta1 and beta2-adrenoceptor agonists.

Adenocarcinoma in the exstrophic bladder.

We report 2 cases of cancerous transformation in an exstrophic bladder. The histology of these tumors, methods of surveillance, and treatment are discussed in conjunction with a review of published reports. These rare tumors are almost entirely adenocarcinomas. Their treatment is surgical (radical cystectomy) with or without associated radiation therapy. Surveillance for patients with bladder exstrophy, whether surgically corrected or not, is indispensable and rests on cystoscopy and urine cytology.

Renal lesions in Von Hippel-Lindau disease: the benign, the malignant, the unknown.

OBJECTIVES: To describe the features and treatment of renal lesions in von Hippel-Lindau disease (VHL) from a series of patients, to highlight important issues in the management of these lesions. MATERIALS AND METHODS: We performed a retrospective study in 7 patients with VHL who underwent surgery for renal lesions between January 1990 and July 1996. The initial evaluation consisted of an abdominal CT scan and renal arteriography. RESULTS: The mean age of patients at the time of discovery was 38 (+/- 12.01 years). All cases were of type 1. Radiology assessment underestimated the gravity of the lesions in 5 patients. In all patients, unilateral surgery was performed with the kidney being conserved in 4 cases. Of the 44 lesions removed, 23 had signs of progressiveness (atypical or malignant cyst, renal cell carcinoma), most of the cancers were of low grade. 84% of the lesions did not exceed 3 cm and 48% were

Influence of beta-adrenoceptor agonists on the pulmonary circulation. Effects of a beta3-adrenoceptor antagonist, SR 59230A.

The aims of this study were (a) to compare in the rat isolated perfused lung preparation, the effects of isoprenaline and of three beta3-adrenoceptors agonists, SR 59104A, (N-[(6hydroxy-1,2,3,4-tetrahydronaphtalen-(2 R)-2yl)methyl]-(2R)-2-hydroxy-2-(3-chlorophenyl)ethanamine hydrochloride), SR 59119A (N[(7-methoxy-1,2,3,4-tetrahydronaphtalen-(2R)-2yl)methyl]-( 2R)-2-hydroxy-2-(3-chlorophenyl)ethanamine hydrochloride) and SR 58611A (ethyl¿(7S)-7-[(2R)-2-(3-chlorophenyl)-2-hydroxyethylamino]-5,6,7, 8-tetrahydronaphtalen-2-yloxy¿acetate hydrochloride) on hypoxia-induced pulmonary vasoconstriction, and (b) to investigate the potential existence of atypical beta-adrenoceptors in these effects. Propranolol (0.1 microM) was used to antagonize beta1- and beta2-adrenoceptors whereas SR 59230A, 3-(2-ethylphenoxy)-1-[(1S)-1,2,3,4-tetrahydronapht-1-ylam ino]-(2S)-2-propanol oxalate) (0.3 microM) was used to block beta3-adrenoceptors. Isoprenaline and the three beta3-adrenoceptors agonists caused concentration-dependent relaxations during the pulmonary pressure response. Propranolol and SR 59230A inhibited the relaxant effects of isoprenaline. SR 59230A but not propranolol inhibited those of SR 59104A. Finally, propranolol and SR 59230A failed to oppose SR 59119A- and SR 58611A-induced relaxant effects. In concentrations > or = 1 microM, SR 59230A caused per se a relaxation of the hypoxic vasoconstricted lung. These results suggest the existence of atypical beta-adrenoceptors in the rat pulmonary vessels.

Role of potassium channels and nitric oxide in the effects of iloprost and prostaglandin E1 on hypoxic vasoconstriction in the isolated perfused lung of the rat.

1. The aims of this study were to compare in the rat isolated perfused lung preparation, the antagonist effects of iloprost, a stable analogue of prostacyclin, and prostaglandin E1 (PGE1) on the hypoxic pulmonary pressure response, and to investigate the possible involvement of KATP and KCa channels and of EDRF (NO) in the effects. In addition, iloprost and PGE1 effects were compared to those of adenosine and forskolin. 2. Isolated lungs from male Wistar rats (260-320 g) were ventilated with 21% O2 + 5% CO2 + 74% N2 (normoxia) or 5% CO2 + 95% N2 (hypoxia) and perfused with a salt solution supplemented with ficoll. Glibenclamide (1 microM), charybdotoxin (0.1 microM), NG-nitro-L-arginine methyl ester (L-NAME, 100 microM) were used to block KATP, KCa channels and NO synthesis, respectively. 3. Iloprost, PGE1, adenosine and forskolin caused relaxation during the hypoxic pressure response. The order of potency was: iloprost > PGE1 = forskolin > adenosine. EC50 values were 1.91 +/- 0.52 10(-9) M, 3.31 +/- 0.58 10(-7) M, 3.24 +/- 0.78 10(-7) M and 7.70 +/- 1.68 10(-5) M, respectively. Glibenclamide, charybdotoxin and L-NAME inhibited partially the relaxant effects of iloprost and forskolin but not those of PGE1. 4. It is concluded that in the rat isolated lung preparation, iloprost and forskolin but not PGE1 dilate pulmonary vessels partly through KATP channels, KCa and nitric oxide release. Furthermore our results suggest that the role of cycli AMP in these effects is not unequivocal.

Comparison of the effects of nicorandil, pinacidil and nitroglycerin on hypoxic and hypercapnic pulmonary vasoconstriction in the isolated perfused lung of rat.

1. The aims of this study were to compare in the rat isolated perfused lung preparation, the dilator actions of nicorandil, pinacidil and nitroglycerin on the hypoxic pulmonary pressure response with or without hypercapnic acidosis and to investigate the possible involvement of K channels and EDRF in these effects. 2. Isolated lungs from male Wistar rats (260-320 g) were ventilated with 21%O2 + 5%CO2 + 74%N2 (normoxia) or 5%CO2 + 95%N2 (hypoxia) and perfused with a salt solution supplemented with ficoll and gassed with 40%CO2 + 60%N2 to produce hypercapnic acidosis. Glibenclamide (1 microM), charybdotoxin (0.1 microM), NG-nitro-L-arginine methyl ester (L-NAME, 100 microM) and methylene blue (30 microM) were used to block KATP channels, KCa channels, EDRF synthesis and guanylate cyclase, respectively. 3. Hypoxic pressure response was significantly increased by hypercapnic acidosis (+115%, P < 0.001), L-NAME (+111%, P < 0.001), methylene blue (+100%, P < 0.05) but not by glibenclamide or charybdotoxin. In contrast none of these inhibitors affected the hypoxic hypercapnic acidosis response. 4. Nicorandil, pinacidil and nitroglycerin caused relaxation during the hypoxic pressure response and hypoxic hypercapnic acidosis response. Nicorandil was more potent in the latter. Glibenclamide inhibited the relaxant effects of nicorandil and pinacidil but not those of nitroglycerin during hypoxia alone. In contrast, glibenclamide inhibited the relaxant effects of the three drugs during hypoxia + hypercapnia. Charybdotoxin inhibited the relaxant effect of pinacidil during normocapnia and hypoxia but not those of nicorandil or nitroglycerin. Methylene blue inhibited partially the dilator response to pinacidil but did not modify the effects of nitroglycerin or nicorandil. 5. It is concluded that in the rat isolated lung preparation, EDRF limits hypoxic pulmonary vasoconstriction but not hypoxic vasoconstriction potentiated by hypercapnic acidosis, whereas KATP or KCa channels are not involved in either case. Nicorandil and pinacidil dilate pulmonary vessels mainly through KATP channels but the effects of pinacidil may also involve an additional mechanism of action through KCa channels. Finally it is suggested that nitroglycerin may partly exert its relaxant effects through KATP channels.

Effects of two K+ channel openers, aprikalim and pinacidil, on hypoxic pulmonary vasoconstriction.

This study investigated the effects of two K+ channel openers, aprikalim and pinacidil, on hypoxic pulmonary vasoconstriction induced in isolated rat lung perfused at constant flow. In order to evaluate the mechanism of the hypoxic vasoconstriction we also studied the effects of an inhibitor of the endothelium-derived relaxing factor (EDRF), NG-nitro-L-arginine methyl ester (100 microM), an inhibitor of the guanylate cyclase, methylene blue (30 microM), two K+ channel blockers, glibenclamide (1 microM) and tetraethylammonium (20 mM). In normoxia, NG-nitro-L-arginine methyl ester, methylene blue, glibenclamide or tetraethylammonium did not enhance significantly the baseline perfusion pressure, suggesting that neither EDRF nor K+ channels are involved in the modulation of the low basal pulmonary vascular tone. In hypoxia, aprikalim and pinacidil (0.03-3 microM) induced a concentration-dependent decrease of pulmonary pressure, exhibiting their spasmolytic effects in acute hypoxia. The hypoxic pressure response was significantly increased by NG-nitro-L-arginine methyl ester, methylene blue and tetraethylammonium, but not by glibenclamide suggesting that EDRF and K+ channels other than ATP-sensitive K+ channels are involved in the modulation of the hypoxic pressure response. The spasmolytic effects of aprikalim and pinacidil (1 microM) were not modified by NG-nitro-L-arginine methyl ester, but were partially reduced by tetraethylammonium and completely abolished by glibenclamide, suggesting that these effects are mainly but not exclusively mediated through ATP-sensitive K+ channel opening.