Levels of matrix metalloproteinase (MMP)-1 in paired sera and synovial fluids of juvenile idiopathic arthritis patients: relationship to inflammatory activity, MMP-3 and tissue inhibitor of metalloproteinases-1 in a longitudinal study

OBJECTIVES

To measure levels of the collagenases matrix metalloproteinase (MMP)-1 and -13 in the synovial fluid (SF) and serum of patients with juvenile idiopathic arthritis (JIA), and to correlate these measurements with inflammatory activity, levels of the collagenase activator MMP-3 and the tissue inhibitor of metalloproteinases-1 (TIMP-1).

METHODS

Levels of MMP-1, -3, -13 and TIMP-1 were measured in paired SF and serum from 82 JIA patients using enzyme-linked immunsorbent assay and compared between subtypes and patients of different ages and disease durations. These levels were also correlated to the active joint count (AJC) and standard measures of inflammatory activity and therapeutic response, including erythrocyte sedimentation rate (ESR) and platelet count (PLT).

RESULTS

MMP-1 was detected in JIA SF and correlated with PLT. MMP-3 levels were high in SF and detectable in serum where they correlated with PLT, ESR and AJC. MMP-13, however, was not detected in SF or serum. No differences were observed between patients grouped by subtype, age or disease duration. MMP-3 contributed the majority of total MMP in SF samples resulting in excess MMP levels over TIMP-1.

CONCLUSIONS

MMP-1 is up-regulated in SF concordant with inflammatory activity in JIA. This was true for patients in all JIA subtypes and age groups, suggesting that the capability for degradation of type II collagen is present in early disease, and throughout the disease course. MMP-3 may be important in the activation of collagenases and the saturation of exogenous inhibitors. Serum MMP-3 may therefore be a useful, measurable and specific marker of active disease in JIA.

Autologous stem cell transplantation for refractory juvenile idiopathic arthritis: analysis of clinical effects, mortality, and transplant related morbidity

OBJECTIVE

To evaluate the safety and efficacy of autologous stem cell transplantation (ASCT) for refractory juvenile idiopathic arthritis (JIA).

DESIGN

Retrospective analysis of follow up data on 34 children with JIA who were treated with ASCT in nine different European transplant centres. Rheumatological evaluation employed a modified set of core criteria. Immunological reconstitution and infectious complications were monitored at three month intervals after transplantation.

RESULTS

Clinical follow up ranged from 12 to 60 months. Eighteen of the 34 patients (53%) with a follow up of 12 to 60 months achieved complete drug-free remission. Seven of these patients had previously failed treatment with anti-TNF. Six of the 34 patients (18%) showed a partial response (ranging from 30% to 70% improvement) and seven (21%) were resistant to ASCT. Infectious complications were common. There were three cases of transplant related mortality (9%) and two of disease related mortality (6%).

CONCLUSIONS

ASCT in severely ill patients with JIA induces a drug-free remission of the disease and a profound increase in general wellbeing in a substantial proportion of patients, but the procedure carries a significant mortality risk. The following adjustments are proposed for future protocols: (1) elimination of total body irradiation from the conditioning regimen; (2) prophylactic administration of antiviral drugs and intravenous immunoglobulins until there is a normal CD4+ T cell count.

More 'cries from the joints': assessment of the musculoskeletal system is poorly documented in routine paediatric clerking

OBJECTIVES

The aim of this study was to describe the assessment of the musculoskeletal (MSK) system in comparison with other systems in routine paediatric medical clerking. Furthermore, to survey trainee paediatricians (SPRs, specialist registrars) about their self-rated confidence in assessing the MSK system.

METHODS

Case notes of consecutive general paediatric medical patients admitted to three UK hospitals over a 4-week period were assessed using a standard pro forma. All patients had been assessed by a consultant paediatrician during their admission. A postal questionnaire was sent to all SPRs in training in each of the hospitals, regarding their confidence in assessing the MSK system compared with other systems and their exposure to MSK teaching.

RESULTS

Case notes of 257 patients [117 females, median age 3 yr (range 1-18 yr)] were reviewed. The most common reason for admission was acute infection, although the spectrum of other recorded diagnoses varied between hospitals. Thirteen children (5%) had an acute problem (e.g. infection) against a background of chronic disease. The case note documentation showed that cardiovascular (CVS), respiratory (RS) and gastrointestinal (GI) systems were assessed in the vast majority (>90%) of patients, irrespective of the underlying diagnosis. However, other systems were less well recorded; the trend being the same in each hospital and in descending order, the neurological system (38%), skin (32%), eyes (10%) and musculoskeletal system (4%). Only 2.7% (7/257) patients were documented to have been asked about MSK symptoms, and only 1.6% (4/257) had any documentation of joint examination--in all cases this was limited (e.g. range of movement of the knee only), and no patients had documentation of gait being examined, even in those children presenting with 'limp'. The response rate to the postal questionnaire was 60% (67/112). The self-rated confidence in MSK assessment was markedly low in comparison with other systems, even though 61/67 recalled some teaching of the MSK system as an undergraduate (61/67) or postgraduate (50/67). Of note none could recall teaching as an undergraduate in paediatric MSK assessment and where there had been postgraduate rheumatology MSK teaching this had been delivered by paediatric rheumatologists in many cases (34/50), reflecting the centres participating in the study.

CONCLUSIONS

In routine general paediatric medical in-patient clerking and throughout the admission, MSK assessment was rarely documented, and even where present was limited. This contrasts markedly with other systems which were examined in most children irrespective of the presenting complaint. Self-rated confidence in MSK assessment is low amongst SPRs compared with other systems, despite most recalling some teaching. This discrepancy between teaching and clinical practice needs to be addressed in undergraduate and postgraduate training.

Increased prevalence of dental caries and poor oral hygiene in juvenile idiopathic arthritis

OBJECTIVES

Recent decades have seen a trend to treat juvenile idiopathic arthritis (JIA) with increasing immunosuppression to improve the long-term outcome. Poor oral hygiene and dental decay cause significant morbidity, and patients with chronic disease (who may be further immunocompromised by treatment) are at greater risk. This study investigated patients with JIA using standard measures of oral health.

METHODS

One hundred and forty-nine patients with JIA were included. The children were attending a regional paediatric rheumatology service and the adults were attending an adult rheumatology clinic. Random age- and sex-matched healthy controls were recruited from a dental teaching hospital. The structured dental examination included standard epidemiological indices of oral hygiene (gingival index, plaque index, oral cleanliness index) and dental decay [DMFT (decayed, missing or filled teeth) index].

RESULTS

JIA patients, at all ages, had increased levels of dental decay and poor oral hygiene. This increased level of decay was statistically significant in the patients aged 0-11 yr. Significant levels of untreated caries and increased levels of missing teeth were found in JIA, suggesting that patients with JIA had less restorative dental treatment, with tooth extraction often the chosen option for the treatment of dental decay.

CONCLUSIONS

This is the largest study of oral health in JIA and is cross-sectional with non-diseased controls. It shows significantly increased levels of poor oral hygiene and dental decay in patients with JIA. The high levels of untreated dental decay suggest barriers to dental care. These results emphasize the role of regular dental care in the multidisciplinary management of JIA.

Type and extent of enamel defects in juvenile idiopathic arthritis (JIA)

AIM

To establish whether there is an increased prevalence and extent of enamel defects associated with Juvenile Idiopathic Arthritis (JIA) in patients in the North of England.

STUDY DESIGN

clinical examination of subjects and age and sex matched controls.

METHODS

The labial surfaces of all erupted permanent teeth in subjects, as well as age and sex matched controls, were examined. They were classified for type and extent of defects according to the Modified DDE index. The records of 146 subjects and 142 controls were available for analysis.

STATISTICS

defects were expressed as the percentage of subjects or controls with or without any defects or specific types of defect. Fisher's exact test was used to compare the prevalence of disease in the two groups with significance being accepted at the 5% level. In addition, 95% confidence intervals for the relative risk of disease in the two groups were derived.

RESULTS

There was no significant difference between subjects and controls for the presence of any type of defect (p=0.48), demarcated opacities (p=0.39), diffuse opacities (p=0.71), or hypoplasias (p=0.19). There was no significant increase in severity of defects in subjects compared with controls. There was also no significant difference when comparing the group diagnosed before the age of 4 (0-3) and the group diagnosed after the age of 4 (>4) years.

CONCLUSION

There was no greater overall prevalence of enamel defects or specific type of defects and no greater extent of them in subjects with JIA compared with age and sex matched controls.

Sialochemistry in juvenile idiopathic arthritis

OBJECTIVES

To investigate whether there are any differences in salivary flow rates and saliva composition that may contribute to the reported increase in caries prevalence in patients with juvenile idiopathic arthritis (JIA).

DESIGN

Randomized controlled trial.

SETTING

The sialochemistry of children with JIA has rarely been investigated.

METHODS

Unstimulated and stimulated whole saliva was collected from 17 randomly selected JIA patients and 17 age and sex matched controls. Both samples were analysed for salivary flow rate, pH, calcium and phosphate.

RESULTS

Unstimulated and stimulated JIA saliva flow rates, and the flow rate change from unstimulated to stimulated in JIA saliva were all significantly lower than the controls. There were no significant differences in the pH of unstimulated and stimulated JIA saliva compared with the controls, however, the change in pH (from unstimulated to stimulated) in the study group was significantly greater. The JIA patients had non-significantly lower levels of both calcium and phosphate ions in the unstimulated and stimulated samples.

CONCLUSIONS

This data would suggest that there is both a reduced resting salivary flow and a reduced response to stimulation in JIA patients, which may contribute to a previously reported higher caries prevalence.

Regulatory effect of experimental diabetes on the expression of endothelin receptor subtypes and their gene transcripts in the rat adrenal gland

Endothelins (ETs) mediate paracrine control of vascular tone and secretion of steroids and catecholamines in the adrenal gland through two ET receptor subtypes, ETA and ETB. The differential distribution and function of these subtypes are responsible for the multiplicity of endothelin actions in this tissue. This study examines the regulatory effects of experimental diabetes on the gene expression, subtype specificity and localization of ET receptor subtypes, ET isopeptides, and endothelin-converting enzyme-1 (ECE-1) in the rat adrenal gland. The densities, pharmacological properties and distribution of ET receptor subtypes ETA and ETB in adrenal glands from streptozotocin-induced diabetic, insulin-treated diabetic and age-matched control rats were investigated, using radioligand receptor binding and autoradiographic techniques. The gene expression of ETA and ETB receptors ET-1, ET-3 and ECE-1 was evaluated using relative multiplex reverse transcription/PCR. The induction of diabetes caused a marked reduction in body weight but no significant change in adrenal gland size. The density of ET receptors was significantly increased in the diabetic rat adrenal gland, mainly because of an increase in the expression of ETB receptors. Insulin treatment normalized the diabetes-induced changes in the expression levels of ET receptor subtypes to control levels. The expression level of ET-1 mRNA was up-regulated, whereas ET-3 mRNA was down-regulated in the diabetic adrenal gland compared with the controls. The ECE-1 mRNA level in the adrenal gland was not altered by the induction of diabetes. Autoradiographic studies showed that ETA and ETB are the predominant receptor subtypes in the adrenal medulla and cortex respectively. These results suggest that ETA and ETB receptors are differentially distributed and regulated in the diabetic rat adrenal gland.

Properties of alpha-1-adrenergic receptors in the rat prostate: effect of experimental diabetes

We studied the effects of 8 weeks of streptozotocin (STZ)-induced diabetes on the density and the pharmacological properties of alpha1-adrenoceptors in the rat prostate using receptor-binding experiments with [125I]iodo-2[beta-(4-hydroxyphenyl)-ethylaminomethyl]tetralone [125I]HEAT. Saturation experiments showed the presence of specific [125I]HEAT-binding sites in the control and diabetic rat prostate and that the induction of diabetes significantly decreased the density of [125I]HEAT-binding sites in the rat prostate. [125I]HEAT-binding sites in the prostate of both groups were inhibited by prazosin (nonselective), spiperone (alpha1B-selective), WB4101 and 5-methylurapidil (alpha1A-selective) and BMY7378 (alpha1D-selective) with the following rank order of Ki values: prazosin < WB4101 < 5-methylurapidil < spiperone < BMY7378, indicating a similar pharmacological profile of alpha1-adrenoceptor in the 2 groups. Comparing the Ki values of the rat prostate with those obtained from the rat submaxillary gland (alpha1A), rat spleen (alpha1B), rat vas deferens (alpha1A + alpha1B) and those reported for cloned alpha1D, indicates the predominance of the alpha1A + alpha1B or the alpha1A subtype in the rat prostate. The present study demonstrates that STZ-induced diabetes downregulates the expression of alpha1-adrenoceptor in the rat prostate, without significantly affecting the receptor subtype specificity.

Expression of endothelin receptor subtypes and their messenger RNAs in diabetic rat prostate: effect of insulin treatment

Streptozotocin (STZ)-induced diabetes causes an upregulation in the expression of endothelin (ET) receptors in the rat prostate (Eur J Pharmacol 310:197, 1996). We examined the effects of insulin treatment, started 8 weeks after the induction of diabetes, on the expression and distribution of ET receptors and their respective mRNAs in the rat prostate. The densities, pharmacological properties and distribution of ET receptors in the rat prostate were examined using radioligand receptor binding and autoradiographic studies, and gene expression of ET receptors was evaluated utilizing the reverse transcription-polymerase chain reaction (RT-PCR). STZ-injected rats had smaller prostates and reduced serum testosterone levels than control and insulin treated diabetic animals. ET receptor density was shown to be significantly higher in the prostate from diabetic rats than those from either control or insulin treated diabetic animals. The pharmacological profile of prostatic ET receptors was similar in all groups (approximately 80% ET(A); 20% ET(B) subtype). ET receptors were predominantly localized to the prostatic stroma. Induction of diabetes increased the expression of mRNA levels of ET(A) and ET receptors, and insulin treatment reversed this upregulation to control levels. These results indicate that (1) ET receptor subtypes are expressed in the rat prostate as transcription and translation products; (2) insulin can normalize the diabetes-induced upregulation in the expression of ET receptors and their respective mRNAs; and (3) diabetes-induced regression of the prostate may involve an alteration in ET receptors.

Experimental diabetes-induced regression of the rat prostate is associated with an increased expression of transforming growth factor-beta

PURPOSE

Transforming growth factor-beta (TGF-beta), a potent inhibitor of cell growth, plays an important role in the androgen-dependent processes of the prostate through a complex network of growth factors. TGF-beta expression in the prostate is under negative regulatory control of androgen. As experimental diabetes causes a regression of the prostate and decrease in serum testosterone levels in rats, we examined TGF-beta alterations at the mRNA and protein levels in the diabetic rat prostate.

MATERIALS AND METHODS

The expression of TGF-beta1 and TGF-beta2 and their respective mRNAs in prostates from streptozotocin (STZ)-induced diabetic, insulin-treated diabetic and age-matched control rats were investigated, using relative multiplex RT-PCR, semi-quantitative Western blotting, and immunohistochemistry.

RESULTS

Induction of diabetes caused a significant reduction in prostatic weight and in serum testosterone levels in rats. Both mRNA and protein levels of TGF-beta1, and mRNA level of TGF-beta2 were up-regulated in the diabetic rat prostate. Insulin-treatment normalized changes observed in prostatic weight and serum testosterone levels, and reversed the alterations in the TGF-beta1 and TGF-beta2 expression at the gene transcript and protein levels to control levels. Immunohistochemical studies demonstrated that TGF-beta1 is localized to prostatic stromal cells, whereas TGF-beta2 is located in both epithelial and stromal cells.

CONCLUSION

These results suggest that TGF-beta1 and TGF-beta2 may be involved in the diabetes-induced regression of the prostate gland.

Audit of rheumatology services for adolescents and young adults in the UK. British Paediatric Rheumatology Group

BACKGROUND

Juvenile idiopathic arthritis (JIA) is associated with significant morbidity in adulthood with at least one third of children continuing to have active inflammatory disease into their adult years and up to 60% of all patients continuing to have some limitation of their activities of daily living. A survey of service provision for these young people in the transition from paediatric to adult rheumatology care was therefore undertaken.

METHODS

A postal questionnaire was sent to all 92 members of the British Paediatric Rheumatology Group, representing 61 units providing a paediatric rheumatology service in the UK and Eire.

RESULTS

Fifty-five replies were received representing a 60% completion rate of doctors and 84% of units on the mailing list. The majority of respondents were adult rheumatologists (n = 36, 65%) with 42% of respondents based in teaching hospitals. A median of 24 patients (new and follow-up, range 1-225) were seen in a median of two paediatric rheumatology clinics (range 0-15) per month. Eighteen per cent of units had a dedicated adolescent clinic (n = 9) with a median of one clinic per month and a median number of new patients per month of two (range 0-24) and 10 review patients (4-32). All the adolescent clinics involved an adult rheumatologist with five having a paediatrician in clinic and four having access to a paediatrician. The majority of clinics involved a specialist registrar (n = 6), a nurse specialist (n = 6), an occupational therapist (n = 6) and a physiotherapist (n = 5). The majority of clinics had flexible entry and exit criteria. In seven clinics there was a standardized process of transfer, first discussed at a median age of 13 yr (range 12-16) but no unit provided literature or organized pre-visits for this process. A demand for patient information resources (e.g. disease and drug information, careers) specifically aimed at adolescents with rheumatic diseases was identified. Generic health issues were only addressed by two clinics. Obstacles to current service provision and ideas for future developments were identified.

CONCLUSIONS

This survey identifies a heterogeneity of provision of healthcare for adolescents with rheumatic disease and highlights the potential for further research and development.

Expression and localization of basic fibroblast growth factor in diabetic rat prostate

OBJECTIVE

To assess fibroblast growth factor-2 (FGF2/bFGF), which is important in the development and maintenance of the normal prostate and in the development of human benign prostatic hyperplasia (BPH) and prostatic carcinoma, in an animal model of experimentally induced diabetes. Materials and methods Using Western blotting and immunohistochemical analyses, the expression of FGF2 in prostates from several groups of rats was investigated. Rats had diabetes for 8 or 16 weeks (induced by intravenous injection with 65 mg/kg streptozotocin); rats were also treated with insulin (starting 8 weeks after the induction of diabetes, for 8 weeks), and two further groups acted as age-matched control rats. Immunohistochemical markers for smooth muscle (alpha-actin) and epithelium (cytokeratin) were used to distinguish different cell types in adjacent prostatic sections.

RESULTS

Diabetic rats had smaller prostates and lower serum testosterone levels than their controls; insulin treatment of diabetic rats increased prostatic size and testosterone levels. As shown by Western blotting, diabetes caused greater FGF2 expression than in controls, whereas reverse-transcriptase polymerase chain reaction studies showed similar levels of prostatic FGF-2 mRNA in all groups. Immuno-histochemical studies showed that FGF-2 was expressed in both stromal and epithelial components of the rat prostate. Furthermore, although the expression of FGF2 was higher in epithelial than stromal cells in control prostates, it was distributed uniformly in the diabetic prostate.

CONCLUSION

The differences in the level of expression and pattern of distribution of FGF2 suggests a potential role for FGF2 in the changes observed in prostatic growth in diabetic rats.

Oral health and juvenile idiopathic arthritis: a review

Juvenile idiopathic arthritis (JIA) results in significant morbidity that includes an adverse impact on oral health that is generally not well recognized. This review describes current literature which demonstrates poor oral health in children with JIA. The impact of JIA on oral health is probably multifactorial and these factors are discussed. This review emphasizes the role of paediatric dentistry in the multidisciplinary management of JIA and highlights the need for further research.

Cystic pelvic pathology presenting as falsely elevated post-void residual urine measured by portable ultrasound bladder scanning: report of 3 cases and review of the literature

Dedicated portable ultrasound devices generally offer a rapid, noninvasive, largely operator-independent means of assessing post-void residual urine (PVR) volume. In most published series, PVR measured by portable ultrasound correlates well with catheterized urine volume. We report 3 cases in which follow-up of falsely elevated PVR measurements on ultrasound resulted in comparatively low catheterized volumes. In all 3 cases, the elevated readings were due to cystic ovarian pathology, which was diagnosed by formal radiologic evaluation and ultimately confirmed operatively in 2 cases. Cystic pathology of the pelvis or lower abdomen may present as an elevated PVR on ultrasound and low urine volume on subsequent catheterization and should prompt further evaluation.

Gene expression, localization, and pharmacological characterization of endothelin receptors in diabetic rat bladder dome

As there are significant amounts of functional endothelin receptors in the mammalian urinary tract, we examined the effect of experimental diabetes on the expression of endothelin receptors and their mRNAs in the rat bladder dome. The density of endothelin receptors in the rat bladder dome was higher (8 and 16 weeks following the onset of diabetes) than in age-matched controls. Insulin treatment, started 8 weeks after the induction of diabetes, partially reversed the endothelin receptor alterations. The pharmacological profile of the endothelin receptors in the bladder dome was similar in all groups and was consistent with the predominance of the endothelin ET(A) receptor subtype (ET(A):ET(B)=approximately 4:1). Autoradiographic studies demonstrated that the endothelin receptors were located in all tissue components of the bladder, including epithelial and muscular layers. Semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) data indicated that diabetes increased the expression level of gene transcripts for both endothelin receptor subtypes and that insulin treatment reversed the mRNA upregulation.

A randomized double-blind trial of oral L-arginine for treatment of interstitial cystitis

PURPOSE

Nitric oxide synthase activity is decreased in the urine of patients with interstitial cystitis compared to the urine of controls. In a preliminary trial oral L-arginine, the substrate for nitric oxide synthase, increased urinary nitric oxide synthase activity and improved interstitial cystitis symptoms. This randomized, double-blind, placebo controlled study further investigates the efficacy of L-arginine treatment for interstitial cystitis.

MATERIALS AND METHODS

A total of 53 interstitial cystitis patients were assigned to receive daily 1,500 mg. L-arginine or placebo orally for 3 months. Interstitial cystitis symptoms were assessed by interviews at 2 weeks, and 1, 2 and 3 months.

RESULTS

The trial was completed by 21 of 27 patients in the L-arginine group and 25 of 26 in the placebo group. Using per protocol analysis 29% (6 of 21 patients) in the L-arginine group and 8% (2 of 25) in the placebo group were clinically improved by the end of the trial (p = 0.07). A Likert scale showed greater global improvement in the L-arginine group (48%, 10 of 21) compared to the placebo group (24%, 6 of 25) at 3 months (p = 0.05) with a decrease in pain intensity (p = 0.04), and tendency toward improvement in urgency (p = 0.06) and frequency of pain (p = 0.09). Using an intention to treat approach to analysis there were no differences between groups.

CONCLUSIONS

Oral L-arginine (1,500 mg. daily) may decrease pain and urgency in a subset of interstitial cystitis patients.

Juvenile chronic arthritis: a dental review

A review of the literature relating to juvenile chronic arthritis (JCA) is presented. It includes a description of the disease itself and identifies our knowledge of the increased risk of dental disease associated with this condition. In addition the impact of JCA therapy on the dental management of the patient is discussed. The review highlights the need for further research into the effects of the disease on dental caries, periodontal disease and saliva.

Choice and stimulus-response compatibility affect duration of response selection

In general, for movements to visual targets, response times increase with the number of possible response choices. However, this rule only seems to hold when an incompatibility exists between the stimulus and response, and is absent when stimulus and response are highly compatible (e.g., when reaching toward the location of the stimulus). Stimulus-response (S-R) compatibility can be manipulated either at the level of stimulus and response characteristics, or at the level of the mapping between elements of the stimulus and response sets. The current study was undertaken to determine the extent of the interaction between choice and each of these two levels of S-R compatibility. Subjects used a joystick to move a cursor in response to two, four or eight possible cues, with S-R compatibility manipulated along two dimensions (type of stimulus, and mapping between stimulus and response sets) in separate blocks of trials. Choice effects were absent when S-R relationships were highly compatible, moderate when incompatible in either of the two dimensions, and greatest when incompatible in both dimensions. These results indicate that choice affects response selection at each stage in the decoding of S-R relationships. Similar but smaller effects were seen for trials in which the stimulus was the same as that presented in the immediately preceding trial, suggesting that repeated stimulus-response transformations are faster and more efficient due to the priming effects of previous trials.

Characterization, localization and distribution of alpha1 adrenoceptor subtype in male rabbit urethra

PURPOSE

The subtype specificity, localization and distribution of urethral alpha1-adrenoceptors were studied in the male rabbit urethra.

MATERIALS AND METHODS

The properties of the urethral alpha1-adrenoceptors were investigated using radioligand receptor binding and light microscopic autoradiography with [125I]iodo-2-[b-(4-hydroxyphenyl)-ethylaminomethyl]tetralone (HEAT), and immunohistochemistry with monoclonal anti-alpha smooth muscle actin and anti-alpha sarcomeric actin antibodies.

RESULTS

Saturation experiments with [125I]HEAT demonstrated the presence of significant amounts of a single high affinity binding site for alpha1 adrenoceptors in the male rabbit urethra. The pharmacological profile of the alpha1 adrenoceptors in rabbit urethra, determined by inhibition experiments with subtype selective alpha1 adrenoceptor antagonists, was characterized by the following rank order of potency of inhibition constants (Ki values): prazosin < or = WB 4101 < spiperone < 5-methylurapidil < BMY 7378. The pKi values for the rabbit urethra were correlated with the pKi values for rat spleen, submaxillary glands, and vas deferens and for those reported for cloned alpha1d receptors with correlation coefficients of 0.68, 0.929, 0.909, and 0.523, respectively.

CONCLUSIONS

The pharmacological characterization demonstrates the predominance of alpha1A or alpha1A + alpha1B adrenoceptor subtype(s) in male rabbit urethral smooth muscle. Furthermore, the autoradiographic and immunohistochemical studies show a heterogeneous distribution of alpha1 adrenoceptors along the longitudinal axis of the urethra, within the smooth muscle fibers, with the receptors being localized more densely in the proximal than in the distal urethra.