Star formation inside a galactic outflow.

Recent observations have revealed massive galactic molecular outflows that may have the physical conditions (high gas densities) required to form stars. Indeed, several recent models predict that such massive outflows may ignite star formation within the outflow itself. This star-formation mode, in which stars form with high radial velocities, could contribute to the morphological evolution of galaxies, to the evolution in size and velocity dispersion of the spheroidal component of galaxies, and would contribute to the population of high-velocity stars, which could even escape the galaxy. Such star formation could provide in situ chemical enrichment of the circumgalactic and intergalactic medium (through supernova explosions of young stars on large orbits), and some models also predict it to contribute substantially to the star-formation rate observed in distant galaxies. Although there exists observational evidence for star formation triggered by outflows or jets into their host galaxy, as a consequence of gas compression, evidence for star formation occurring within galactic outflows is still missing. Here we report spectroscopic observations that unambiguously reveal star formation occurring in a galactic outflow at a redshift of 0.0448. The inferred star-formation rate in the outflow is larger than 15 solar masses per year. Star formation may also be occurring in other galactic outflows, but may have been missed by previous observations owing to the lack of adequate diagnostics.

Stress response of Salmo salar (Linnaeus 1758) facing low abundance infestation of Caligus rogercresseyi (Boxshall & Bravo 2000), an object in the tank, and handling.

This study looks at how low infestation loads of adult Caligus rogercresseyi and other stressors affect the physiology of Salmo salar. Experimental fish groups were with (infested) or without (control) exposure to the parasite. The parasite cohort was followed for 78 days post-infestation (dpi), and only adult lice were observed. Additional stressors were applied at 60 and 75 dpi. The analysis included measurements of fish physiology and weight. Low-level infestations by adult C. rogercresseyi for more than 50 dpi induced moderate stress in S. salar as well as a high energy demand and increased small skin mucous cells. Threshold lice loads were identified, and above those loads, a high stress response was observed. Additional stressors altered fish physiology, inducing downregulation of the cortisol response after the first stressor and upregulation after the second stressor, but infested fish responded more strongly. Parasitism by C. rogercresseyi is energetically demanding, affecting the primary and secondary responses (e.g. cortisol and glucose levels), as well as the tertiary response (fish weight).

Vascular angiotensin AT1 receptor neuromodulation in fetal programming of hypertension.

Fetal stress increases the susceptibility to cardiovascular diseases in adult age, including hypertension, a process known as fetal programming of hypertension (FPH). This study intends to investigate the interplay between vascular sympathetic nervous system (SNS) and RAS, namely the neuromodulatory role exerted by Angiotensin II (Ang II) receptor-1 (AT1) in FPH, and respective contribution for hypertension. METHODS: 6-month old Sprague-Dawley offspring from mothers fed ad-libitum (CONTROL) or with 50% intake during the second half of gestation (maternal undernutrition, MUN) were used. Sympathetic neurotransmission was studied in mesenteric/tail arteries and mesenteric veins by electrically-evoked [3H]-noradrenaline release experiments using RAS drugs. AT1 receptors in sympathetic nerves of mesenteric arteries were investigated by immunohistochemistry and Laser Scanning Confocal Microscopy. RESULTS: Ang II facilitated noradrenaline release in the vessels studied from MUN and CONTROL rats. Losartan induced a tonic facilitation only in MUN vessels. Sympathetic innervation was larger in MUN versus CONTROL vessels. AT1 receptors on sympathetic nerves were present in higher amounts in MUN versus CONTROL vessels. CONCLUSIONS: Findings support that FPH is associated with a vascular hyper-sympathetic activation, involving a tonic facilitation of prejunctional AT1 receptors by endogenous Ang II, which can justify, at least in part, the development of hypertension.

[Neurodevelopment and phenocopies of attention deficit hyperactivity disorder: differential diagnosis]. / Neurodesarrollo y fenocopias del trastorno por deficit de atencion/hiperactividad: diagnostico diferencial.

INTRODUCTION: Attention deficit hyperactivity disorder (ADHD) is one of the most prevalent neurodevelopmental disorders. Other neurodevelopmental disorders may appear as a comorbidity or mimicking ADHD itself. DEVELOPMENT: This study reviews the high prevalence of other neurodevelopmental disorders (specific learning difficulties, communication disorders, etc.) in patients with ADHD. Moreover, the possible differential diagnoses include the same neurodevelopmental disorders that can occur as a comorbidity. Based on the literature, the study evaluates the role of clinical evaluation and neuropsychology in distinguishing between comorbidity and mimicry. CONCLUSIONS: The clinical evaluation could be insufficient for the comorbid diagnosis of neurodevelopmental disorders. In these cases, a neuropsychological evaluation is generally required, since it can also offer alternative diagnostic hypotheses about the symptoms observed and may therefore be a valuable aid for the differential diagnosis.

TITLE: Neurodesarrollo y fenocopias del trastorno por deficit de atencion/hiperactividad: diagnostico diferencial.Introduccion. El trastorno por deficit de atencion/hiperactividad (TDAH) es uno de los trastornos del neurodesarrollo mas prevalentes. Otros trastornos del neurodesarrollo pueden aparecer de forma comorbida o mimetizar el propio TDAH. Desarrollo. Se revisa la elevada prevalencia de otros trastornos del neurodesarrollo (trastornos especificos del aprendizaje, trastornos de la comunicacion...) en los pacientes con TDAH. Por otro lado, entre los posibles diagnosticos diferenciales se situan los mismos trastornos del neurodesarrollo que pueden aparecer de forma comorbida. Se valorara, de acuerdo a la bibliografia, el papel de la valoracion clinica y la neuropsicologia en la distincion entre comorbilidad y mimetismo. Conclusiones. La valoracion clinica podria ser insuficiente para el diagnostico comorbido de los trastornos del neurodesarrollo. En estos casos, la valoracion neuropsicologica es generalmente necesaria; esta puede igualmente ofrecer hipotesis diagnosticas alternativas de la sintomatologia observada y, por tanto, ser util para el diagnostico diferencial.

[Attention deficit hyperactivity disorder: from a neurodevelopmental perspective]. / Trastorno por deficit de atencion/hiperactividad: perspectiva desde el neurodesarrollo.

INTRODUCTION: Neurodevelopmental disorders cover a heterogeneous group of disorders such as intellectual disability, autism spectrum disorders or specific learning difficulties, among others. The neurobiological and clinical variables seem to clearly justify the recent inclusion of attention deficit hyperactivity disorder (ADHD) as a neurodevelopmental disorder in the international classifications. DEVELOPMENT: Neurodevelopmental disorders are characterised by their dimensional nature and the distribution of the different symptoms in the population. These aspects are reviewed, specifically from the perspective of the clinical features and the neuropsychology of ADHD. The dimensional symptomatic nature of ADHD contrasts with the diagnostic criteria of this disorder according to different classifications or clinical guidelines. It also contrasts with the data collected by means of different complementary examinations (scales, tests, etc.). CONCLUSIONS: It is essential to understand the clinical continuum within each neurodevelopmental disorder (including ADHD), among the different neurodevelopmental disorders, and among the neurodevelopmental disorders and normality for their research, diagnosis and management. The development of instruments that provide support for this dimensional component is equally significant.

TITLE: Trastorno por deficit de atencion/hiperactividad: perspectiva desde el neurodesarrollo.Introduccion. Los trastornos del neurodesarrollo engloban a un grupo heterogeneo de trastornos como la discapacidad intelectual, el trastorno del espectro autista o los trastornos especificos del aprendizaje, entre otros. La reciente inclusion en las clasificaciones internacionales del trastorno por deficit de atencion/hiperactividad (TDAH) dentro de los trastornos del neurodesarrollo parece claramente justificada atendiendo a variables neurobiologicas y clinicas. Desarrollo. El caracter dimensional y la distribucion de diferentes sintomas en la poblacion caracterizan a la mayoria de los trastornos del neurodesarrollo. Se revisan estos aspectos, particularmente desde la sintomatologia y neuropsicologia en el TDAH. El caracter sintomatico dimensional del TDAH contrasta con los criterios diagnosticos de este trastorno de acuerdo a diferentes clasificaciones o guias clinicas. Contrasta igualmente con los datos recogidos a traves de diferentes exploraciones complementarias (escalas, tests...). Conclusiones. El entendimiento del continuo clinico dentro de cada trastorno del neurodesarrollo (incluido el TDAH), entre los diferentes trastornos del neurodesarrollo, y entre los trastornos del neurodesarrollo y la normalidad, es esencial para la investigacion, el diagnostico y el abordaje de todos ellos. El desarrollo de instrumentos que avalen este componente dimensional es igualmente trascendental.

[Dysfunction in attention deficit hyperactivity disorder: assessment and response to treatment]. / Disfuncion en el trastorno por deficit de atencion/hiperactividad: evaluacion y respuesta al tratamiento.

Attention deficit hyperactivity disorder (ADHD) is a heterogeneous, symptomatically complex disorder. Its cardinal symptom, the presence of dysexecutive problems, emotional dysregulation of many of them and its own comorbidity, among others, will condition its clinical expression and the dysfunction. Classifying ADHD as a 'disorder' calls for an accurate assessment of the terms 'dysfunction' or 'repercussion'. The progress made in the classification and quantification of the symptoms characterising ADHD should be applied to measuring and objectifying dysfunction. Considering dysfunction as a simple interference, however clear it may be, could lead to an overestimation of the diagnosis of this disorder. Just as its estimation is essential for a diagnosis, it is also necessary for the correct evaluation of the efficacy of the therapeutic interventions, especially in the medium and long term. Further studies are needed in this sense to appraise the efficacy of the treatments, whether pharmacological or not, in different domains (social relationship, learning, self-esteem, quality of life, accidents, etc.).

TITLE: Disfuncion en el trastorno por deficit de atencion/hiperactividad: evaluacion y respuesta al tratamiento.El trastorno por deficit de atencion/hiperactividad (TDAH) es un trastorno heterogeneo y complejo sintomaticamente. Su sintomatologia cardinal, la presencia de problemas disejecutivos, la desregulacion emocional de muchos de ellos y la propia comorbilidad, entre otros, condicionaran su expresion clinica y la disfuncion. La tipificacion del TDAH como 'trastorno' requiere una evaluacion precisa del termino 'disfuncion' o 'repercusion'. Los avances en la tipificacion y cuantificacion de la sintomatologia caracteristica del TDAH deberian trasladarse a la medicion y objetivacion de la disfuncion. La estimacion de la disfuncion como una simple interferencia, por clara que sea, podria llevar a una sobreestimacion del diagnostico de este trastorno. Del mismo modo que es ineludible su estimacion para el diagnostico, es igualmente necesaria para la correcta evaluacion de la eficacia de las intervenciones terapeuticas, especialmente a medio y largo plazo. Son necesarios estudios adicionales en este sentido para valorar la eficacia de los tratamientos, sean farmacologicos o no, en diferentes dominios (relacion social, aprendizaje, autoestima, calidad de vida, siniestralidad…).

Effect of fetal undernutrition and postnatal overfeeding on rat adipose tissue and organ growth at early stages of postnatal development.

Intrauterine and perinatal life are critical periods for programming of cardiometabolic diseases. However, their relative role remains controversial. We aimed to assess, at weaning, sex-dependent alterations induced by fetal or postnatal nutritional interventions on key organs for metabolic and cardiovascular control. Fetal undernutrition was induced by dam food restriction (50 % from mid-gestation to delivery) returning to ad libitum throughout lactation (Maternal Undernutrition, MUN, 12 pups/litter). Postnatal overfeeding (POF) was induced by litter size reduction from normally fed dams (4 pups/litter). Compared to control, female and male MUN offspring exhibited: 1) low birth weight and accelerated growth, reaching similar weight and tibial length by weaning, 2) increased glycemia, liver and white fat weights; 3) increased ventricular weight and tendency to reduced kidney weight (males only). Female and male POF offspring showed: 1) accelerated growth; 2) increased glycemia, liver and white fat weights; 3) unchanged heart and kidney weights. In conclusion, postnatal accelerated growth, with or without fetal undernutrition, induces early alterations relevant for metabolic disease programming, while fetal undernutrition is required for heart abnormalities. The progression of cardiac alterations and their role on hypertension development needs to be evaluated. The similarities between sexes in pre-pubertal rats suggest a role of sex-hormones in female protection against programming.

Genetic predisposition to albuminuria is associated with increased arterial stiffness: role of elastin.

BACKGROUND AND PURPOSE: The Munich Wistar Frömter (MWF) rat strain represents an experimental model to study cardiovascular alterations under conditions of progressive albuminuria. The aim of this study was to evaluate the association between genetic predisposition to albuminuria and the development of arterial stiffness and/or vascular remodelling. EXPERIMENTAL APPROACH: Experiments were performed in mesenteric arteries from 12-week-old MWF, Wistar Kyoto (WKY) and consomic MWF-6(SHR) and MWF-8(SHR) rats in which chromosomes 6 or 8 associated with albuminuria from MWF were replaced by the respective chromosome from spontaneously hypertensive rats (SHR). KEY RESULTS: Incremental distensibility, wall stress and strain were reduced, and arterial stiffness was significantly increased in albuminuric MWF compared with WKY. Albuminuria suppression in both consomic strains was associated with lower ß-values in MWF-8(SHR) and MWF-6(SHR) compared with MWF. Moreover, elastin content was significantly lower in MWF external elastic lamina compared with WKY and both consomic strains. In addition, a reduction in arterial external and internal diameter and cross-sectional area was detected in MWF compared with WKY, thus exhibiting an inward hypotrophic remodelling. However, these alterations remained unchanged in both consomic strains. CONCLUSION AND IMPLICATIONS: These data demonstrate that albuminuria in MWF is associated with increased arterial stiffness due to a reduction of elastin content in the external elastic lamina. Moreover, inward hypotrophic remodelling in MWF is not directly associated with albuminuria. In contrast, we demonstrated that two major genetic loci affect both the development of albuminuria and arterial stiffness, thus linking albuminuria and impairment of mechanical properties of resistance arteries.

Cellular aspects of vascular remodeling in hypertension revealed by confocal microscopy.

Cellular aspects of remodeling in intact arteries have not been fully investigated, mainly due to the lack of an appropriate methodology that allows for simple measurements. The aim of this study was to develop a method based on laser scanning confocal microscopy (LSCM), compare it with previous methodology, and apply it to the study of remodeling in hypertension. The morphology of mesenteric resistance arteries from stroke-prone spontaneously hypertensive rats (SHRSP) and Wistar-Kyoto rats (WKY) was determined with wire myography on one segment with a standardized diameter setting (0.9[d100]) and with perfusion myography on a second segment from the same artery at the calculated equivalent pressure. The second segments were stained with the nuclear dye Hoechst 33342 (live tissue) or propidium iodide (fixed tissue) and measured with LSCM and MetaMorph software. Compared with wire myography, perfusion myography showed similar differences from those previously reported. Compared with LSCM, perfusion myography showed a similar lumen but significantly smaller wall thickness in both live and fixed tissue, probably due to measurement underestimation. In the study with LSCM, arteries from SHRSP compared with those from WKY showed (1) reduced lumen, (2) altered cell density that was significantly increased in the adventitia, decreased in the media, and unchanged in the intima, (3) significantly increased medial volume, (4) significantly smaller endothelial cell nuclei, and (5) adventitial-like cells in the media. We conclude that (1) LSCM is a reliable and straightforward method to study morphology in intact vessels, (2) it provides new information on the cellular changes in remodeling, (3) adventitia might play an active role in the process of remodeling in hypertension, and (4) endothelium "remodels" in hypertension.

Neurogenic component of ouabain-evoked contractions is modulated by the endothelium.

The influence of endothelium on the neurogenic component of ouabain-induced contractions in isolated perfused guinea pig carotid arteries was analyzed. Ouabain (0.1 mumol/L to 0.1 mmol/L) evoked concentration-dependent increases of perfusion pressure. Phentolamine (0.3 to 10 mumol/L) and prazosin (30 nmol/L to 10 mumol/L) (nonselective antagonist of alpha-adrenergic receptors and selective antagonist of alpha 1-adrenergic receptors, respectively) induced a concentration-dependent relaxation in segments precontracted with ouabain (0.1 mmol/L). When the arteries were preincubated with those blockers (both at 3 mumol/L) or the animals were pretreated with reserpine, the contractions to the glycoside were diminished, indicating that they are partially mediated by norepinephrine release from adrenergic nerve endings. De-endothelialization abolished the effect of adrenergic blockade on ouabain-induced contractions. On the other hand, de-endothelialization did not modify significantly the effect of the adrenergic blockade on norepinephrine-induced contractions. The nitric oxide blocker oxyhemoglobin, at concentrations (10 mumol/L) that abolished endothelium-dependent relaxations induced by 3 mumol/L acetylcholine; or the cyclooxygenase blocker indomethacin (10 mumol/L) did not modify the relaxation caused by phentolamine. In bioassay experiments, 30 mumol/L phentolamine induced a relaxation on the ouabain-elicited contraction only when the glycoside was added through a donor segment with endothelium. Ouabain-induced tritiated norepinephrine release was significantly reduced by the removal of endothelium but not by 1 mumol/L oxyhemoglobin or 1 mumol/L indomethacin. These results suggest that the endothelium modulates the neurogenic component involved in contractions evoked by the glycoside by a diffusible factor (or factors) whose nature is unknown; however, the factor is neither nitric oxide nor a cyclooxygenase-related compound.

Genes encoding atrial and brain natriuretic peptides as candidates for sensitivity to brain ischemia in stroke-prone hypertensive rats.

-Previous studies suggested that atrial natriuretic peptide gene (Anp) and brain natriuretic peptide gene (Bnp) are plausible candidate genes for susceptibility to stroke and for sensitivity to brain ischemia in the stroke-prone spontaneously hypertensive rat (SHRSP). We performed structural and functional analyses of these 2 genes in SHRSP from Glasgow colonies (SHRSPGla) and Wistar-Kyoto rats from Glasgow colonies (WKYGla) and developed a radiation hybrid map of the relevant region of rat chromosome 5. Sequencing of the coding regions of the Anp and Bnp genes revealed no difference between the 2 strains. Expression studies in brain tissue showed no differences at baseline and at 24 hours after middle cerebral artery occlusion. Plasma concentrations of atrial natriuretic peptide (ANP) did not differ between the SHRSPGla and WKYGla, whereas concentrations of brain natriuretic peptide were significantly higher in the SHRSPGla as compared with the WKYGla (n=11 to 14; 163+/-21 pg/mL and 78+/-14 pg/mL; 95% confidence interval 31 to 138, P=0.003). We did not detect any attenuation of endothelium-dependent relaxations to bradykinin or ANP in middle cerebral arteries from the SHRSPGla; indeed the sensitivity to ANP was significantly increased in arteries harvested from this strain (WKYGla: n=8; pD2=7. 3+/-0.2 and SHRSPGla: n=8; pD2=8.2+/-0.15; P<0.01). Moreover, radiation hybrid mapping and fluorescence in situ hybridization allowed us to map the Anf marker in the telomeric position of rat chromosome 5 in close proximity to D5Rat48, D5Rat47, D5Mgh15, and D5Mgh16. These results exclude Anp and Bnp as candidate genes for the sensitivity to brain ischemia and pave the way to further congenic and physical mapping strategies.

Functional reduction and associated cellular rearrangement in SHRSP rat basilar arteries are affected by salt load and calcium antagonist treatment.

The stroke-prone spontaneously hypertensive rat (SHRSP) is a strain with high incidence of cerebrovascular accidents increased by salt-rich diet and decreased by calcium-antagonist treatment. In the SHRSP rat basilar artery the authors have previously shown reduced contractility and altered structure including regions of smooth muscle cell (SMC) disorganization. The aims of this study have been to analyze (1) the morphology of these abnormal regions, (2) the structural modifications responsible for the reduced function, and (3) the effect of salt and calcium-antagonist treatment on vascular structure and function. Wistar Kyoto and SHRSP rats, untreated or treated from week 8 through 14 with 1% NaCl or 1% NaCl + 1 mg x kg(-1) x d(-1) lacidipine, were used. Function was studied with wire myography. Structure was analyzed in fixed intact arteries with confocal microscopy. Basilar arteries from SHRSP rat showed (1) reduced contractility, (2) discrete foci of SMC disarray with altered proportion of adventitia to SMC, and (3) decreased SMC and increased adventitial cell number. Arteries from salt-loaded SHRSP rats showed a higher degree of SMC disarray and further reduction in contractility. Lacidipine treatment of salt-loaded rats significantly improved structure and function. These data suggest that vascular remodeling can provide an explanation for the observed reduction in vascular contractility of SHRSP rat basilar arteries and might show light on the effects of salt load and calcium-channel blockers in life span and the incidence of cerebrovascular accidents in SHRSP rats.

Measurements of vascular remodeling by confocal microscopy.

The introduction of myographs was crucial for the study of structure and function of resistance arteries. The ability to support and maintain small blood vessels paved the way for true microscopic studies of the vascular cells. However, even after decades of study, we still do not know very much about the "normal" arrangement of smooth muscle cells in the vascular wall and how their distribution affects function. It was clearly time for the next technological step forward. We have shown here how the combination of myography and confocal microscopy creates a platform for the study of vascular structure at the cellular level and in 3D. In addition, the possibility of using live myograph-mounted vessels in combination with LSCM opens a new field of research to assess vascular remodeling from a physiological point of view and to study vascular function at a level not achieved by any other method at present. Now that the hardware is in place it is time to concentrate on the software and improve the methods of analysis. We have used 2D analysis of 3D data sets to describe differences in vascular structure and, at the same time, developed methods to semiautomate the process. The success of the 3D methods will ultimately depend on the reliability and accuracy of the analysis routines. There are still problems to overcome en route to finding a complete solution. However, we believe that the search for a robust fully (or semi-) automated method of 3D analysis will be more than worthwhile. We have defined vascular remodeling to include any changes in cellular arrangement or morphology. However, on a more subtle level, changes in receptors, enzymes, and proteins leading to altered functionality could also be regarded as remodeling. In that respect it may be interesting to map the distribution of the many receptors, channels, and proteins that regulate vascular growth, death, and function. Currently, there is a growing list of fluorescent ligands and antibodies that can be used in conjunction with confocal microscopy. It is possible that multiple stains could be used and imaged at different wavelengths with a view to constructing full 3D models of various structures and their colocalization. It is our belief that the confocal approach will prove to be a major tool in unraveling the complexities of cell-cell interactions and arrangements and will allow a better understanding of the process of vascular remodeling and function.

Cellular changes induced by chronic nitric oxide inhibition in intact rat basilar arteries revealed by confocal microscopy.

BACKGROUND: Cellular aspects of remodelling have not been investigated fully in intact vessels due to lack of appropriate methodology. OBJECTIVE: To determine the cellular alterations induced by chronic inhibition of nitric oxide (NO) production in intact rat basilar arteries by combined use of perfusion myography and a laser scanning confocal microscope. METHODS: Wistar-Kyoto rats were treated with 10 mg/kg per day NG-nitro-L-arginine methyl ester (L-NAME) for 3 weeks. Basilar arteries from treated and age-matched Wistar-Kyoto rat controls were mounted on a perfusion myograph, stained with the nuclear dye Hoechst 33342 and fixed under pressure. The segments were mounted on a slide and visualized using the 364 nm line of a laser scanning confocal microscope. MetaMorph software was used to obtain optical sections from the vessel and for morphology determinations. RESULTS: L-NAME treatment induced hypertension (systolic blood pressure control 129.2+/-2.7 mmHg and SBP L-NAME treatment 176.3+/-5.2 mmHg, P< 0.001). Compared with control rat arteries, arteries from treated rats had a reduced lumen diameter, similar wall thickness and an increased wall: lumen ratio. L-NAME treatment induced specific changes in adventitia, media and intima, namely an increase in number of adventitial cells and in adventitia thickness, a reduction in number of smooth muscle cells with no change in media thickness and reductions in number of endothelial cells, size of nuclei and luminal surface area. CONCLUSIONS: Hypertension induced by chronic inhibition of NO production is associated with eutrophic remodelling of rat basilar artery. However, within this overall maintenance of constant volume, there are marked cellular changes in adventitia, media and intima. The separate contributions of inhibition of NO production and hypertension to the remodelling process need to be elucidated.

Alpha 1-adrenoceptor vasoconstriction in the tail artery during ageing.

1. We have studied the alpha 1-adrenoceptor-mediated responses in intact tail artery rings from 3-4 and 20-22 months old Sprague-Dawley rats, focusing on possible endothelial alterations. The influence of nitric oxide released by the endothelium, the number of alpha 1-adrenoceptors and the functional receptor reserve were evaluated to determine their contribution to the contractile response mediated by this receptor. The state of the endothelial layer was assessed by confocal microscopy. 2. Noradrenaline (1 nM-100 microM) induced concentration-dependent vasoconstriction. The maximum contractions to noradrenaline (P < 0.05) and to 75 mM KCl (P < 0.01) were higher in young than in old animals. 3. The density (Bmax) of alpha 1-adrenoceptors and the dissociation constant (KD) obtained in [3H]-prazosin binding experiments were unchanged by age. 4. The apparent affinity (pKA) and the percentage of functional receptors (qx 100) remaining after phenoxybenzamine (0.03 microM) were similar in both age groups. 5. After partial alpha 1-adrenoceptor inactivation with phenoxybenzamine, NG-nitro-L-arginine methylester (30 microM) significantly potentiated the E/[A] curve to noradrenaline in young rats. However, only responses to 0.1 to 1 microM noradrenaline were significantly potentiated in old animals. In addition, 94% of the vessels from young, but only 52% from old rats were relaxed by 80-100% of the noradrenaline (0.03 microM) contraction, with 1 microM acetylcholine. 6. No modifications in the area (micron2) or in the number of endothelial nuclei (per mm2) were observed between age groups. An elongation of the nuclei of endothelial cells was observed in the old animals. 7. These data suggest that the noradrenaline-induced contraction is decreased in old rats probably due to differences in either the contractile machinary or postreceptor mechanisms. These alterations may be accompanied by an impairment of the release or production of NO from endothelial cells.

Presynaptic M2-muscarinic receptors on noradrenergic nerve endings and endothelium-derived M3 receptors in cat cerebral arteries.

The muscarinic (M) receptors involved in the vasodilation elicited by acetylcholine (ACh) and in the carbachol inhibition in electrically induced [3H]noradrenaline (NA) release in cat cerebral arteries was investigated. For this, atropine, pirenzepine, AF-DX 116, 4-DAMP, non-specific, M1, M2 and M3 receptor antagonists, respectively, were used. ACh elicited concentration-dependent relaxations up to 10(-6) M which were attenuated by these antagonists; the order of potency (pA2 values) to inhibit the ACh-induced relaxation was: atropine (10.1) 4-DAMP (8.9) greater than pirenzepine (7.6) greater than AF-DX 116 (5.9). The electrical stimulation (200 mA, 0.3 ms, 2 Hz, during 1 min) of these arteries preincubated with [3H]NA caused tritium release which was inhibited by carbachol (10(-6) M). The 4 antagonists attenuated the action of the M agonist; the order of potency (pIC50 values) was: atropine (8.7) greater than 4-DAMP (8.1) greater than AF-DX 116 (7.9) greater than pirenzepine (5.8). The action of McN-A-343, a putative M1 agonist, was also investigated. This agent produced small vasodilator responses and elevated concentrations (5 x 10(-5) M) inhibited the stimulated NA release, which was partially antagonized by atropine (10(-7) M) and pirenzepine (10(-8) and 10(-7) M). These results suggest the existence of M3 and M2 receptors mediating the relaxation induced by ACh and the NA release inhibition evoked by carbachol, respectively.

Confocal microscopy for structure and real-time pharmacology in blood vessels.

The structure and composition of living small blood vessels can be studied in great detail in three dimensions using confocal microscopy. Individual cells and their components can be visualised by vital dyes for the nucleus, cytoplasm or extracellular space. Specific ligands can then localise individual components such as membrane receptors with great precision. Cell function is unaffected, allowing the study, in real time, of the changing relation and contribution to vascular contraction or dilatation of different cell types particularly smooth muscle, endothelium and adventitia. This allows not only visualisation but quantification, using image analysis software. These techniques will be of particular value in assessing the contribution of form to function in pathological situations such as vascular remodelling in hypertension.

Characterization of the subtype of presynaptic alpha 2-adrenoceptors modulating noradrenaline release in cat and bovine cerebral arteries.

The possible existence of a heterogeneous population of alpha 2-adrenoceptors (alpha 2A and alpha 2B, demonstrated by binding studies) in adrenergic nerve endings of cat and bovine cerebral arteries modulating noradrenaline release was investigated. Electrical field stimulation elicited an increase of tritium secretion from these vessels preincubated with (+/-)-[3H]noradrenaline, which was reduced by the alpha 2-agonists, clonidine (1 microM) and B-HT 920 (0.01 and 0.1 microM), in cat cerebral arteries but only by B-HT 920 in bovine cerebral arteries. This reduction was inhibited by the antagonist of the alpha 2B-subtype, prazosin, and the antagonists of alpha 2A- and alpha 2B-subtypes yohimbine and particularly rauwolscine. The effect of B-HT 920 was partially inhibited by clonidine in bovine, but not in cat cerebral arteries. In both types of arteries, prazosin, yohimbine and the alpha 1-agonist methoxamine (all at 1 microM) failed to modify the stimulated radioactivity liberation, whereas it was increased by 1 microM rauwolscine, and by yohimbine plus prazosin in cat cerebral arteries. The basal tritium release was enhanced by rauwolscine and prazosin in cat cerebral arteries but only by the latter in bovine cerebral arteries. These results suggest: (1) the existence of presynaptic alpha 2-adrenoceptors, mainly of the alpha 2B-subtype, in these vessels negatively modulating noradrenaline release, their activity being greater in cat than in bovine cerebral arteries, and (2) clonidine has no agonistic but a weak antagonistic action in the latter vessels.