Coordination régionale et suivi prospectif du traitement prophylactique et curatif de 301 patients traités par anticorps monoclonaux anti-SARS-CoV-2

Introduction

La pandémie a particulièrement mis en danger nos patients immunodéprimés et questionne notre place dans l’organisation de l’administration des anticorps monoclonaux à titre préventif et curatif. L’objectif de l’étude a été d’évaluer l’activité d’une cellule régionale mise en place pour évaluer l’indication, organiser le traitement prophylactique ou curatif par anticorps monoclonaux ou par antiviraux, quelle que soit la pathologie chronique des patients concernés.

Matériels et méthodes

La cellule « anticorps monoclonaux et traitements du COVID », composée d’un médecin coordonnateur, de médecins retraités, et d’une secrétaire médicale, a été mise en place début janvier 2022 grâce à un financement par l’ARS. Tous les médecins ont été informés par l’ARS et les URPS, des critères d’éligibilité aux anticorps monoclonaux et du rôle de la cellule dans l’évaluation de l’indication, l’aide apportée pour la demande d’accès précoce et la logistique (injections en hospitalisation de jour ou en hospitalisation à domicile (HAD)). Les structures d’HAD ont été spécifiquement formées aux formalités de prescription, à l’administration et au suivi de ces patients. Les patients ayant reçu un traitement prophylactique ont été recontactés par la cellule la semaine suivant l’injection, 3 mois et 6 mois suivant l’injection. Des questionnaires ont été adressés aux médecins généralistes pour évaluer leur perception concernant les anticorps monoclonaux et les antiviraux.

Résultats

Au total, 216 patients (dont 121 patients ayant des facteurs de risque cardiovasculaire) ont reçu un traitement prophylactique par anticorps monoclonaux (Evusheld), pour les indications suivantes : 110 patients transplantés d’organe, 95 patients traités par anti-CD20, 2 patients traités par chimiothérapie, 8 patients ayant d’autres facteurs d’immunodépression et 1 contre-indication au vaccin. Les sollicitations de la cellule dans cette indication émanaient quasi exclusivement de médecins spécialistes. Avec un suivi médian de 6 mois, aucun événement indésirable (EI) grave, y compris cardiovasculaire, n’est survenu. Des EI non graves ont été observés chez 50 patients (23 %). Trente patients (14 %) ont été infectés par le SARS-CoV-2, dont 2 ont été traités par anticorps monoclonaux à titre curatif et 2 par Paxlovid. Aucun patient n’a été hospitalisé pour COVID, aucun n’a développé de COVID sévère. Sur les 214 patients recontactés pour une ré-administration d’anticorps à visée prophylactique, 12 (5 %) l’ont refusée. Au total, 85 patients ont été traités par anticorps monoclonaux à visée curative dont 3 par Ronapreve, 68 par Xevudy, 14 par Evusheld, dont 53 (62,3 %) en HAD et 30 patients ont été traités par Paxlovid. Les sollicitations de la cellule dans cette indication émanaient le plus souvent de médecins généralistes. Aucun effet indésirable grave n’a été observé.

Conclusion

La coordination régionale pour l’aide au traitement par anticorps monoclonaux et antiviraux est utile pour faciliter la prescription de ces traitements. Le suivi prospectif confirme leur tolérance très satisfaisante. Cette coordination a également permis d’évaluer les difficultés rencontrées par les médecins généralistes, en partie liées au caractère innovant, aux difficultés logistiques ou aux contraintes administratives de ces traitements.

An embedded neutral layer for advanced surface affinity control in grapho-epitaxy directed self-assembly

Advanced surface affinity control for grapho-epitaxy directed self-assembly (DSA) patterning is essential for providing reliable DSA-based solutions for the development of semiconductor patterning. Independent control of surface affinity between the bottom and the sidewalls of a topographical guiding structure was achieved by embedding an ultrathin layer in the guiding template stack. The implementation of an embedded layer with tunable surface properties for DSA grapho-epitaxy was evaluated and optimized on 300 mm wafers by critical dimension SEM characterization. It was demonstrated that a thin protective layer, placed between the hard mask guiding template and the embedded layer, allows the preservation of the surface properties of the embedded layer during guiding template etching. The DSA performances of this novel grapho-epitaxy integration, using a topographical template patterned with 193 nm immersion lithography, were evaluated by monitoring the success rate and the critical dimension uniformity of the shrunk contacts. FIB-STEM analyses were further carried out to analyze the residual polymer thickness on the resulting contacts. This new integration leads to the control of the polymer residual thickness (a few nanometers) and uniformity (inferior to 1 nm) at the bottom of the guiding template which will facilitate the subsequent DSA pattern transfer.

Influence of preoperative cognitive status on propofol requirement to maintain hypnosis in the elderly

BACKGROUND

The loss of cholinergic neurones in the basal forebrain has been shown to correlate to the extent of cognitive dysfunction during ageing in humans and to the hypnotic potency of propofol in animal models. We examined how the preoperative cognitive status, as assessed by mini-mental state examination (MMSE), may interact with propofol consumption during anaesthesia in the elderly.

METHODS

In a prospective study, we recruited 41 patients (65-99 yr) undergoing surgery for hip fracture. Femoral nerve block was performed for analgesia. Target-controlled infusion of propofol (Schnider's model) was adjusted to the bispectral index within the range 40-60. Multiple linear regression analysis determined whether age, BMI, gender, duration of anaesthesia, and preoperative MMSE score affected the propofol consumption (general linear model, Systat 8.0).

RESULTS

BMI and MMSE score significantly affected the mean value of propofol consumption. A low MMSE score (below 19) was associated with an observed decrease in propofol requirement in patients >65 yr of age. No significant effect of age, gender, and duration of anaesthesia on the propofol consumption was observed.

CONCLUSIONS

Propofol requirement to maintain hypnosis during general anaesthesia appears to decrease with deterioration in the cognitive status in the elderly. We suggest that a cognitive dysfunction linked to a cerebral cholinergic dysfunction may influence the brain sensitivity for propofol in aged patients.

[Biological rhythms for anaesthesia and intensive care]

Knowledge of biological rhythms has led to better understanding of the time-of-day dependent effects of anaesthetic drugs. These chronopharmacological effects are currently explained by the biological rhythms modulating the pharmacokinetic, toxic and pharmacodynamic parameters of these substances. Such effect has been described for general anesthetics, local anaesthetics, analgesics as well as for antibiotics. But recent data also highlight that general anaesthetics, probably part of their brain effects, also alter the regulation of biological rhythms, including the sleep-wake or the endogenous circadian temperature rhythms. This desynchronization of biological rhythms can led to disturbance of the circadian secretion of many substances, including hormones. Finally, biological rhythms have been also described with regard to physiology of pain and cardiovascular physiopathology. The concept of biological rhythm should be present in mind not only for the clinical management of patients but also for setting studies in the field of anaesthesia, pain and intensive care.

Complication neuroméningée d’une infection systémique à Candida albicans chez un prématuré

INTRODUCTION

Systemic maternal-fetal Candida albicans infections are uncommon diseases with a poor outcome. An associated cerebromeningeal infection increases morbidity. We present a case of neuromeningeal candidiasis following systemic neonatal infection in a premature infant. Management and therapeutic difficulties are outlined.

OBSERVATION

The patient was a male infant born preterm at 30 weeks gestation. During his first week of life, he developed a systemic infection with an associated symptomatic hydrocephalus. Systemic candidaisis with neuromeningeal complication was diagnosed five weeks later. Despite treatment including cerebrospinal fluid (CSF) shunting and antimycotic medications (flucytosin and amphotericin B), the candidal infection did not resolve. Infectious and mechanical complications of the CSF drainage were treated by several surgical interventions during the following months. At 10 months of life, there was clinical and laboratory evidence of active persistent neuromeningeal candidaisis. Finally, candidal infection was eradicated with intravenous administration of fluconazole. After five year follow-up, the intellectual and psychological status of the patient was quite satisfactory, and no neurological deficits were found on clinical examination.

DISCUSSION

Management of neuromeningeal candidaisis in premature infants is a challenging task particularly because of delayed diagnosis. Candida infection should routinely be suspected in cases of systemic infection with neurological impairment in premature infants. Fluconazole may constitute an efficient therapeutic option.

Mechanisms of action of midazolam on expression of contextual fear in rats

BACKGROUND

Midazolam may suppress conditioned fear after an aversive event by disrupting the memory trace formed during conditioning, by altering the emotional part of the aversive event, or by the combination of both effects. The purpose of the present study was to determine whether affective-related processes contribute to the amnesic-like effects of midazolam on aversive events.

METHODS

The effects of acute administration of low doses of midazolam (0.37-3 mg kg(-1)) on fear conditioning (association between a neutral context and an aversive stimulus) and on innate anxiety in fearful surroundings were examined in rats. The effect of midazolam on the deleterious consequences of pre-exposure to the context (a non-aversive event) for subsequent fear conditioning was then compared with its effect on fear conditioning. The role of midazolam as an affective context was assessed by performing the testing phase under midazolam. Possible locomotor impairment or long-term effects of midazolam were controlled in additional experiments.

RESULTS

Midazolam reduced both contextual fear conditioning and spontaneous fear. The deleterious effect of midazolam on pre-exposure to the context was of the same magnitude as its effect on the acquisition phase of fear conditioning. The effects of midazolam on both pre-exposure to the context and fear conditioning were unchanged when rats received a second injection of midazolam before the retention phase.

CONCLUSIONS

Low doses of midazolam that do not impair locomotion suppress conditioned fear to the context by acting on memory processes rather than on affective or anxiolytic processes.

VACUTEX: a dressing designed for patients, tailored by nurses

VACUTEX is a new rapid capillary action dressing comprising three layers: two 100% polyester filament outer layers, and a 65% polyester and 35% cotton woven inner layer. The outer surfaces are fused in such a way as to prevent micro fibres shedding within the wound bed. No two wounds are alike, and wounds are often located in difficult-to-dress areas. This article will describe how VACUTEX, when used with creativity, addresses many of the challenges of wound management.

Central cholinergic depletion induced by 192 IgG-saporin alleviates the sedative effects of propofol in rats

We examined the effect of central cholinergic depletion on the sedative potency of propofol in rats. Depletion was produced by intracerebroventricular administration of an immunotoxin specific to cholinergic neurones (192 IgG-Saporin; 2 microg). As a result of this lesion, acetylcholine concentration was reduced by about 40% in the frontoparietal cortex and in the hippocampus but was essentially normal in the striatum and cerebellum. Sedation in rats was assessed as the decrease in locomotor activity. Sedative potency of propofol (30 mg kg(-1) i.p.) was reduced by about 50% in rats who received the injection of 192 IgG-Saporin as compared to controls. These results show that a central cholinergic depletion alleviates the sedative effect of propofol, and indicates that basal forebrain cholinergic neurones might mediate part of the sedative/hypnotic effects of propofol.

[How to read a scientific paper. Committee for Clinical References of the French Anesthesia and Resuscitation Society]

Every scientific article has to undergo a critical reading before its conclusions can be accepted. This article discusses the tools for assessing the scientific value of a study. A sequence of methodological criteria allows quality evaluation of an article and its classification in a scale of level of proof.

Combined lesions of cholinergic and serotonergic neurons in the rat brain using 192 IgG-saporin and 5,7-dihydroxytryptamine: neurochemical and behavioural characterization

This study assessed behavioural and neurochemical effects of i.c.v. injections of both the cholinergic toxin 192 IgG-saporin (2 microgram) and the serotonergic toxin 5,7-dihydroxytryptamine (5,7-DHT; 150 microgram) in Long-Evans female rats. Dependent behavioural variables were locomotor activity, forced T-maze alternation, beam walking, Morris water-maze (working and reference memory) and radial-maze performances. After killing by microwave irradiation, the concentrations of acetylcholine, monoamines and 5-hydroxyindoleacetic acid (5-HIAA) were measured in the hippocampus, frontoparietal cortex and striatum. 192 IgG-saporin reduced the concentration of acetylcholine by approximately 40% in the frontoparietal cortex and hippocampus, but had no effect in the striatum. 5,7-DHT lesions reduced the concentration of serotonin by 60% in the frontoparietal cortex and 80% in the hippocampus and striatum. Noradrenaline was unchanged in all structures except the ventral hippocampus where it was slightly increased in rats given 192 IgG-saporin. Cholinergic lesions induced severe motor deficits but had no other effect. Serotonergic lesions produced diurnal and nocturnal hyperactivity but had no other effect. Rats with combined lesions were more active than those with only serotonergic lesions, showed motor dysfunctions similar to those found in rats with cholinergic lesions alone, and exhibited impaired performances in the T-maze alternation test, the water-maze working memory test and the radial-maze. Taken together and although cholinergic lesions were not maximal, these data show that 192 IgG-saporin and 5,7-DHT lesions can be combined to selectively damage cholinergic and serotonergic neurons, and confirm that cholinergic-serotonergic interactions play an important role in some aspects of memory, particularly in spatial working memory.

Effect of nonsedative doses of propofol on an innate anxiogenic situation in rats

BACKGROUND

The effect of propofol on anxiety has not been well studied. In humans, such investigations are confused by the fact that sedation often coexists with anxiolysis. Therefore, the authors evaluated the effects of minimal sedation with propofol in rats placed in an innate anxiogenic situation, the elevated plus-shaped maze.

METHODS

In experiment 1, spontaneous locomotor activity was determined in rats as a measure of sedative effect induced by propofol (0-9 mg/kg administered intraperitoneally). In experiment 2, groups of rats received propofol (0-9 mg/kg) or diazepam (0-2 mg/kg) and then were placed on a plus-shaped maze elevated above the ground that was composed of two opposite closed arms and two opposite open arms. On an initial exposure to the maze, undrugged rats avoid the open arms, with the number of entries into and time spent within the open arms constituting approximately 20% of their total activity. This reflects normal anxiety in a rodent for any elevated open platform.

RESULTS

In experiment 1, 0-9 mg/kg propofol did not alter spontaneous activity in rats. In experiment 2, propofol and diazepam significantly increased the number of entries into and the time spent within the open arms. Propofol at a dose of 9 mg/kg significantly increased the rats' level of exploration of the open arms to about 50% of all exploratory activity, and a similar observation was made with 2 mg/kg diazepam.

CONCLUSIONS

In a standard animal model, propofol has anxiolytic properties at doses that do not produce sedation.

[Intracranial surgery in the lateral position]

The lateral posture (Park Bench) is now widely used. It provides a comfortable position for the surgeon and a convenient brain relaxation. However the positioning is complex and carries a risk of stretching of the brachial plexus. Spatial orientation is more difficult and requires surgical experience. The lateral position does not modify the haemodynamic and respiratory function in healthy patients. In the opposite, various cardiac or respiratory effects of right or left lateral position can occur in patients with cardiac and/or respiratory pathology.

[The sitting position in neurosurgery: the viewpoint of the surgeon]

The sitting position offers the benefits of better access to the apex of the posterior fossa, and an improved exploration and dissection because blood and cerebral spinal fluid drain away from the operative site. Specific complications of the sitting position include cardiovascular instability, jugular venous obstruction, airway oedema, quadriplegia, displacements of catheters and the endotracheal tube, ulnar, sciatic and lateral peroneal nerve compression, venous air embolism, and tension pneumocephalus. In the only existing comparative study, the differences were an increased bleeding in the horizontal position and a better cranial nerve preservation in the sitting position. This argues strongly for teaching and use of the sitting position whenever surgically indicated.

The anxiolytic effect of gamma-hydroxybutyrate in the elevated plus maze is reversed by the benzodiazepine receptor antagonist, flumazenil

The effects of gamma-hydroxybutyrate (GHB), a product of gamma-aminobutyric acid (GABA) metabolism which possesses neuromodulatory properties in brain, were investigated in the elevated plus maze in rats. The number of entries and the time spent in the open arms of the maze were increased by GHB (50, 150, 250 mg/kg i.p.). This is classically considered as indicative of an anxiolytic effect of the drug. There was no sedative effect at these doses as measured by the spontaneous locomotor activity in the actimeter or the total number of arm entries. The anxiolytic properties of GHB were reversed by neither the GHB receptor antagonist, NCS-382 (6,7,8,9-tetrahydro-5(H)-5-olylidene acetic acid) (300 mg/kg i.p.), nor the opioid receptor antagonist, naloxone (10 mg/kg i.p.). However the anti-anxiety effect of GHB was antagonized by the benzodiazepine receptor antagonist, flumazenil (10 mg/kg i.p.), suggesting an interaction of GHB with the GABA(A) receptor complex which mediates the anti-anxiety effect of benzodiazepines.

Effect of midazolam on propofol-induced positive affective state assessed by place conditioning in rats

BACKGROUND

The effect of either midazolam or the combination of midazolam and propofol on the affective state was assessed in rats at subanesthetic doses and at recovery from anesthesia.

METHODS

The putative drug(s)-induced affective states were repeatedly paired with one of two distinguishable compartments of an experimental cage, whereas the vehicle(s)-induced effect was repeatedly paired with the other compartment. During a subsequent choice test for one compartment over the other, the rats' preference for the drug(s)-paired compartment over the vehicle(s)-paired compartment is indicative of a pleasant state induced by the drug(s). In experiment 1, rats were conditioned with different doses of midazolam either at subanesthetic states or at recovery from anesthesia. In experiment 2, groups of rats were conditioned with different combinations of midazolam and propofol either at subanesthetic states or at recovery from anesthesia induced jointly by midazolam (10 mg/kg) and propofol (60 mg/kg). Experiment 3 was conducted in the same way as experiment 2, except that midazolam was paired with both compartments. In addition, these groups were tested not only in an undrugged state but also in a drugged (with midazolam) state.

RESULTS

In experiment 1, rats exhibited a place preference for the environment previously associated with midazolam, at subanesthetic and anesthetic doses. Experiment 2 showed that a propofol-induced place preference was found to be dose-dependently suppressed by midazolam. Experiment 3 replicated the findings of experiment 2 and extended them to the mechanism by which midazolam blocked a propofol-induced place preference.

CONCLUSIONS

Midazolam administered before propofol blocked the expression of a propofol-induced pleasant state.

Early assessment of transplanted liver function: lignocaine clearance test (MEGX)

The purpose of this study was to assess the value of lignocaine biotransformation into monoethylglycinexylidide (MEGX) and conventional liver function tests in the early post-operative period as an indicator of graft function and as a diagnostic tool for complications after hepatic transplantation. Monoethylglycinexylidide formation, plasma bilirubin, aspartate aminotransferase (ASAT), alanine aminotransferase (ALAT), factor V index (FVI) and prothrombin time index (PTI) were measured in 71 patients undergoing 80 liver transplantations respectively at 12 (T1), 24 (T2), 48 (T3) and 72 h (T4) after liver graft revascularization. Patients were divided into two group according to the post-operative outcome. Patients with favourable outcome (n = 59) had significantly higher monoethylglycinexylidide synthesis, higher factor V index and prothrombin time index plasma concentrations, lower bilirubin, ASAT and ALAT plasma concentration (P < 0.0001 at T2 and T3) than those with complicated time course (n = 21). Monoethylglycinexylidide synthesis was the best discriminant of a favourable outcome, whereas bilirubin and ALAT concentrations were associated with complications (bilirubin for primary non function [PNF], ALAT for acute rejection). Thus, the combination of parameters at T2 was a very efficient predictor of primary non function, acute rejection and an uncomplicated time course.

Effect of propofol on affective state as assessed by place conditioning paradigm in rats

BACKGROUND

Whether propofol produces a pleasant affective state remains unclear from clinical studies. In the current study, the effect on affective state of subanesthetic and anesthetic doses of propofol was assessed at a preclinical level with rats in a place conditioning paradigm. Propofol was compared with methohexital.

METHODS

In the place conditioning paradigm, propofol-induced effect was repeatedly paired with one of two distinguishable compartments of the apparatus, whereas the vehicle-induced effect was repeatedly paired with the other compartment. During a subsequent free-choice test, a preference for the drug-paired compartment over the vehicle-paired compartment would be indicative of pleasant state induced by the drug. For all experiments, the conditioning session lasted 8 days and consisted of four pairings of the drug with one compartment and four pairings of the equivalent volume of vehicle with the other compartment. In experiment 1A, four groups of rats were designated according to the dose of propofol that they received intraperitoneally: 0,30,60, or 90 mg/kg. In experiment 1B, the same procedure was used with subanesthetic doses of intraperitoneal methohexital: 0,10,20, or 30 mg/kg. In experiment 2, the rats were conditioned during the recovery period from short-term anesthesia. For one group, anesthesia was induced by propofol (100 mg/kg) whereas for the other group, anesthesia was induced by an equivalent anesthetic dose of methohexital (40 mg/kg).

RESULTS

In experiment 1A, the 30-mg/kg, 60-mg/kg, and 90-mg/kg groups showed a place preference for the drug-paired compartment, but only the group conditioned with 60 mg/kg propofol significantly differed from the 0-mg/kg group. In experiment 1B, the groups conditioned with methohexital showed no place preference for the drug-paired compartment. In experiment 2, the rats showed a place preference for the compartment in which they recovered from propofol-induced anesthesia but no place preference for the compartment in which they recovered from methohexital-induced anesthesia.

CONCLUSIONS

Propofol, but not methohexital, induced a pleasant affective state in rats at subanesthetic doses as well as during recovery from an anesthetic dose.

Fetal pulse oximetry during labor of 62 patients

The objectives of the study were to assess the ability of a fetal pulse oximeter to measure the fetal oxygen saturation (SPO2) continuously during labor and to assess the correlation between readings of fetal pulse oximetry and cord blood gases at birth. The Nellcor N-400 Fetal Oximeter was used in 62 women prospectively. The mean SPO2 was unchanged at the different stages of normal labor. 53.3 +/- 9.1 to 50.1 +/- 11.8% (n = 50). The SPO2 recorded during the pushing phase of stage II (n = 40) was correlated significantly with umbilical cord arterial pH (r = 0.55; p = 0.0002), venous pH (r = 0.63; p = 0.0001), venous PCO2 (r = 0.47; p = 0.002) and venous PO2 (r = 0.39; p = 0.01). SPO2 was also correlated with scalp pH (r = 0.52; p < 0.05; n = 21). No side effects were noted. Fetal pulse oximetry could be useful to assess fetal oxygenation during labor and at birth.

[Antibiotic prophylaxis and appendectomy]

Analysis of clinical studies shows that a single preoperative systematic administration of antibiotics may reduce postoperative sepsis rate after appendicectomy. If the appendix is gangrenous or perforated, this therapy must last for a longer time and is not considered as a prophylaxis. In clinical practice, there are obvious advantages in the use of a single agent efficient against both aerobes and anaerobes. According to the literature, cefotetan or cefoxitin (2 g in adults, 40 mg.kg-1 in children) can be proposed.

[Information to relatives of organ donors. Factors of consent or refusal. Results of a multicenter study]

The French law on organ harvesting in brain dead patients allows this to be done without the family's consent, but prescribes to inform the relatives. Despite this, most teams do not harvest organs if the family is strongly opposed to the procedure. Information given to the relatives is therefore a very important point in the management of the donor. This prospective multicentre enquiry was designed to assess the conditions in which relatives were informed, and to determine the criteria which improve the rate of consent for the donation. After such information had been given, a questionnaire was filled in and sent to France-Transplant. Two hundred and seven interviews were analysed over an 18-month period. In two thirds of cases, the relatives were interviewed less than three hours after the diagnosis of brain death had been made. A written information sheet was used in only one third of interviews. Information was given by telephone in 11% of cases. Organ donation was accepted, on average, in 74% of cases. This ratio, which did not depend on the hospital, increased with the age of the donor: 66% for donors aged less than 18 years to 86% for those more than 50 years old. The aetiology of brain death was not a factor determining acceptance of the donation. The main factor was the conditions of interview: acceptance rate was the highest when there was a one hour delay between giving the information on the donor's brain death and that concerning organ donation.(ABSTRACT TRUNCATED AT 250 WORDS)

Role of cyclic AMP in the prejunctional alpha 2-adrenoceptor modulation of noradrenaline release from the rat tail artery

Experiments were designed to evaluate the effect of cyclic AMP on the electrically-induced release of noradrenaline from vascular sympathetic nerve terminals. The possible implication of the inhibition of adenylate cyclase in the negative feed-back control by prejunctional alpha 2-adrenoceptors of neurotransmitter release was also investigated. Rat isolated tail arteries were preincubated with [3H]-noradrenaline; the preparations were subsequently perfused/superfused with [3H )-noradrenaline-free medium and their perivascular nerves were field stimulated with 24 pulses at 0.4 Hz (0.3 ms, 200 mA). 2 compounds known to enhance the intracellular concentration of cyclic AMP, namely the membrane permeant analogue 8-Br-cAMP (10-300 mumol/l) and forskolin (0.3-10 mumol/l), an activator of adenylate cyclase, concentration-dependently enhanced the stimulation-evoked tritium overflow. The 1,9-dideoxy derivative of forskolin, which does not stimulate adenylate cyclase, was ineffective. Exposure to the cyclic AMP phosphodiesterase inhibitor rolipram 30 mumol/l produced a moderate increase (about 20%) in tritium overflow. However, in the presence of rolipram the facilitatory effect of forskolin was significantly more pronounced than in its absence. Whereas 8-Br-cAMP produced a slight concentration-dependent enhancement of the stimulation-induced vasoconstriction, forskolin and rolipram depressed it. The alpha 2-adrenoceptor agonist B-HT 933 (3-30 mumol/l) concentration-dependently inhibited the tritium overflow. The effect of B-HT 933 30 mumol/l was slightly, but significantly reduced in the presence of 8-Br-cAMP 100 and 300 mumol/l, but was not changed in the presence of forskolin 3 mumol/l. The facilitatory effect of rauwolscine 1 mumol/l was enhanced in the presence of 8-Br-cAMP 100 mumol/l. During perfusion with 8-Br-cAMP 100 mumol/l, the current strength and frequency were decreased to 150 mA and 0.2 Hz, respectively in order to obtain similar amounts of tritium overflow to those observed in the absence of the cyclic AMP analogue with the initial stimulation parameters. Under these conditions, the inhibition of the overflow by B-HT 933 30 mumol/l and the facilitation by the alpha 2-adrenoceptor antagonist rauwolscine 1 mumol/l were unaltered as compared to controls under initial stimulation conditions. It is concluded that, in the rat tail artery, the terminals of perivascular sympathetic nerves are endowed with an adenylate cyclase system. Cyclic AMP is able to modulate noradrenaline release, but does not appear to play a role in the initiation of the release process itself. In addition, the results do not support the hypothesis that prejunctional alpha 2-adrenoceptors depress noradrenaline release through the inhibition of adenylate cyclase.