Recurrent focal segmental glomerulosclerosis in the renal allograft: single center experience in the era of modern immunosuppression.

FSGS is an important cause of ESRD and tends to recur in allografts (rFSGS). Older series suggest recurrence rates of 30-60%. In the modern era of transplant immunosuppression, recurrence rates are unknown. There are also few data regarding prevalence of known genetic mutations in adult FSGS patients who undergo transplantation. Recently, FSGS has been subdivided into histological variants, which may predict renal outcomes; there is little information on patterns of recurrence and outcomes in these variants. Finally, treatment for rFSGS relies upon up-titrating calcineurin inhibitors and plasmapheresis. Insufficient information exists on the use of these regimens for rFSGS in the era of modern immunosuppression. We conducted a retrospective chart review involving all renal transplant recipients at Columbia University Medical Center from December 1999 to March 2007. Those with biopsy confirmed primary FSGS were included and information regarding baseline characteristics, histologic variants, genetics, treatment, and clinical outcomes were collected. FSGS recurred in 23% of patients. Those with collapsing histology on native kidney biopsy, tended to recur with the same histology. No known genetic mutations were identified among those with recurrence. Plasmapheresis resulted in complete or partial remission in 75% of those with recurrence. Recurrent FSGS resulted in a trend toward the combined outcome of ESRD or death compared to those without recurrence (27% vs. 12%). Modern immunosuppression does not reduce the rate of rFSGS, known genetic mutations are uncommon in such adult patients, collapsing FSGS tends to recur with the same histology, and plasmapheresis may be helpful in the treatment of recurrence.

Peritoneal macrophage depletion by liposomal bisphosphonate attenuates endometriosis in the rat model.

BACKGROUND: Activation of macrophages is central to the implantation of endometriosis (EM). We examined the hypothesis that macrophage depletion by intraperitoneal (IP) injection of liposomal alendronate (LA) could result in EM attenuation in a rat model, thus supporting the notion of the pivotal role of macrophages in EM pathology. METHODS: In this study, 90 rats were subjected to an EM model and were divided randomly into seven groups: five groups were treated by 4x once-weekly IP injections of LA (0.02, 0.1, 1, 5 or 10 mg/kg) and the other two groups received saline injections (control) or empty liposomes. Sham-operated rats also received empty liposomes. Depletion of circulating monocytes was determined by flow cytometry analyzes of blood specimens. Four weeks after the initial surgery, the number, size and weight of implants were recorded, adhesions were graded, macrophage infiltration was assessed and the peritoneal fluid was analyzed for monocyte chemotactic protein 1 (MCP-1) and tumor necrosis factor alpha (TNFalpha). RESULTS: Monocyte depletion following IP LA administration resulted in an inhibitory effect on the initiation and growth of EM implants, as expressed by implantation rate, adhesion scoring, implants' size and weight (>0.1 mg/kg LA, P < 0.05). Reduced numbers of infiltrating macrophages were observed in implants of the 1 mg/kg LA group. Peritoneal fluid MCP-1 levels were negatively correlated with LA dose (P < 0.001), whereas no significant correlation could be found for TNFalpha. CONCLUSIONS: Macrophage depletion using IP LA has been shown to effectively inhibit the initiation and growth of EM implants, in a rat EM model. The clear dose-response effect may be viewed as a confirmation of the validity of the concept and encourages further study.

Incidental atherosclerotic renal artery stenosis in patients undergoing elective coronary angiography: are these lesions significant?

BACKGROUND: Cardiologists often identify atherosclerotic renal artery stenosis (ARAS) during cardiac angiography. The importance of such 'incidental' ARAS (iARAS) is not known. The present study sought to describe renal perfusion using non-captopril (baseline) nuclear renograms in patients with iARAS, and to determine characteristics associated with a positive captopril renogram. METHODS: Patients presenting for non-emergent coronary angiography between June 2001 and February 2006 were angiographically screened for iARAS. Those with >50% stenosis of one or both renal arteries were referred to nephrology and underwent nuclear renography. RESULTS: 131 patients had renograms. The mean age was 73.2 +/-8.1 and median eGFR was 51.2 (40.0, 66.6) ml/min/1.73 m(2). 51% had evidence of reduced perfusion to one kidney, of which 13% were discordant with the angiographic lesion. 9% had positive captopril renograms. Captopril renogram positivity was associated with severe unilateral stenosis (p = 0.02). CONCLUSIONS: In cardiac patients diagnosed with iARAS, the presence of known anatomic lesions did not correlate with captopril renogram positivity. Uncertainty remains as to whether nuclear renography is a poor functional test in this population, or the lesions are not functionally significant. These results lead us to question both the significance of such lesions, and the utility of conducting renograms in this population.

Vitamins and cardiovascular disease.

CVD is a major cause of mortality and morbidity in the Western world. In recent years its importance has expanded internationally and it is believed that by 2020 it will be the biggest cause of mortality in the world, emphasising the importance to prevent or minimise this increase. A beneficial role for vitamins in CVD has long been explored but the data are still inconsistent. While being supported by observational studies, randomised controlled trials have not yet supported a role for vitamins in primary or secondary prevention of CVD and have in some cases even indicated increased mortality in those with pre-existing late-stage atherosclerosis. The superiority of combination therapy over single supplementation has been suggested but this has not been confirmed in trials. Studies have indicated that beta-carotene mediates pro-oxidant effects and it has been suggested that its negative effects may diminish the beneficial effects mediated by the other vitamins in the supplementation cocktail. The trials that used a combination of vitamins that include beta-carotene have been disappointing. However, vitamin E and vitamin C have in combination shown long-term anti-atherogenic effects but their combined effect on clinical endpoints has been inconsistent. Studies also suggest that vitamins would be beneficial to individuals who are antioxidant-deficient or exposed to increased levels of oxidative stress, for example, smokers, diabetics and elderly patients, emphasising the importance of subgroup targeting. Through defining the right population group and the optimal vitamin combination we could potentially find a future role for vitamins in CVD.

The possible association between IVF and breast cancer incidence.

BACKGROUND: The possible association between ovulation-inducing drugs and breast cancer development has been debated. Our aim was to evaluate the incidence of breast cancer in a cohort of women exposed to in vitro fertilization (IVF). METHODS: A retrospective cohort analysis was performed by linkage of the computerized database of all women treated at the IVF Unit at Assaf Harofeh Medical Center between 1986 and 2003, and the Israeli National Cancer Registry. The standardized incidence ratio (SIR) was computed as the ratio between the observed number of breast cancer cases and the expected cases, adjusted for age and continent of birth, in the general population. Tumor characteristics of the IVF patients were studied by reviewing original medical records. RESULTS: 35 breast carcinomas were diagnosed among 3,375 IVF-treated women, compared to 24.8 cases expected (SIR = 1.4; 95% CI 0.98-1.96). Age >or=40 years at IVF treatment (SIR = 1.9; 95% CI 0.97-3.30), hormonal infertility (SIR = 3.1; 95% CI 0.99-7.22), and >or=4 IVF cycles (SIR = 2.0; 95% CI 1.15-3.27) were found to be risk factors to develop breast cancer compared to the general population. Multivariate analysis revealed that women who underwent >or=4 IVF cycles compared to those with one to three cycles were at risk to develop breast cancer, although not significantly (SIR = 1.9; 95% CI 0.95-3.81). Of IVF-treated women 85% had ER(+) tumors and 29% had positive family history. CONCLUSIONS: A possible association between IVF therapy and breast cancer development was demonstrated, especially in women >or=40 years of age. These preliminary findings need to be replicated in other cohort studies.

Measurement of intracellular magnesium in a vascular smooth muscle cell line using a fluorescent probe.

Until recently, direct measurement of intracellular free magnesium has been complex and difficult. However, fluorescent probes are now available, based on the same principle as well-established probes for free calcium. Using one such probe, mag-fura-2, we have estimated basal intracellular magnesium concentrations in the A7r5 rat vascular smooth muscle cell line. This level was unaffected by numerous pharmacological manipulations, including agonist stimulation and depolarisation. The possible implications of these findings are discussed.

Desipramine treatment in normal subjects. Effects on neuroendocrine responses to tryptophan and on platelet serotonin (5-HT)-related receptors.

Normal subjects took the tricyclic antidepressant, desipramine hydrochloride, for 16 days. Following treatment there was an increase in the number of specific binding sites on the platelet for both tritiated imipramine and tritiated LSD, the latter site probably representing a platelet serotonin (5-HT) receptor. During desipramine treatment the prolactin response to tryptophan (L-tryptophan) was enhanced, and this enhancement correlated with the increase in platelet LSD binding. The results confirm previous observations that desipramine administration increases certain 5-HT-mediated neuroendocrine responses. Our findings further indicate that desipramine may alter both 5-HT uptake and 5-HT receptor sensitivity, and suggest that the platelet LSD receptor may in certain conditions provide a useful model of 5-HT receptors in the brain.

The use of ezetimibe in achieving low density lipoprotein lowering goals in clinical practice: position statement of a United Kingdom consensus panel.

There is no doubt that lowering serum cholesterol levels reduces the risk of major coronary events. This evidence has led treatment guidelines to set progressively lower targets for low density lipoprotein cholesterol (LDL-C). However, despite widespread use of statins, substantial numbers of patients do not achieve the LDL-C goals. Using higher doses of statins in an attempt to achieve these targets may increase the risk of serious adverse effects. Furthermore, the use of combination therapy with agents such as bile acid sequestrants, niacin and fibrates has been limited by increased potential for side effects, drug interactions and poor compliance. Ezetimibe, a selective cholesterol transport inhibitor, reduces the intestinal uptake of cholesterol without affecting absorption of triglycerides or fat-soluble vitamins. In clinical studies, ezetimibe 10 mg, in combination with statins or as monotherapy, was well tolerated and reduced LDL-C by 34-53% and 17-18%, respectively. The available evidence for ezetimibe is reviewed. The role of ezetimibe in increasing the proportion of patients attaining LDL-C treatment goals is discussed.

Total antioxidant status and coronary artery calcification in type 1 diabetes.

OBJECTIVE: Type 1 diabetes is associated with a high risk of coronary heart disease (CHD), despite the absence of dyslipidemia. Oxidative modification may render LDLs more atherogenic. We aimed to assess antioxidant status in type 1 diabetes and its association with coronary artery calcification (CAC). RESEARCH DESIGN AND METHODS: Total antioxidant status (TAS) of serum was measured using the Trolox equivalent antioxidant capacity assay in 48 type 1 diabetic and 25 nondiabetic subjects. The presence of CAC was assessed in the diabetic subjects using electron beam computed tomography. RESULTS: TAS was reduced in type 1 diabetic subjects compared with nondiabetic subjects (Mann-Whitney U test, P < 0.0001). There were associations between TAS and HbA(1c) (r = -0.43; P = 0.0026) and duration of diabetes (r = -0.35; P = 0.0157). Significant CAC was considered present if the Agatston score was >10. The diabetic subjects with significant CAC were older (P < 0.0001); had longer duration of diabetes (P = 0.0002); were more likely to have high blood pressure (P = 0.040); had higher total cholesterol concentration (P = 0.039), serum creatinine concentration (P = 0.003), and urinary albumin-to-creatinine ratio (P = 0.022); and had lower serum TAS (P = 0.018) compared with those without significant calcification. In logistic regression with CAC as the dependent variable, TAS was entered as a predictor, and the effects on its predictive value of adding other explanatory variables in bivariate analyses were assessed. The power of TAS to predict CAC was independent of many of the traditional CHD risk factors. Whereas TAS as a predictor was no longer statistically significant when age or duration of diabetes were entered into the model, the odds ratio for a TAS concentration above the median value predicting significant CAC only increased from 0.19 to 0.26 and 0.32, respectively. CONCLUSIONS: TAS is reduced in type 1 diabetes and is associated with the presence of CAC.

Role of polyamines in hypertension induced by angiotensin II.

OBJECTIVE: The aim was to investigate the involvement of polyamines in the development of cardiovascular hypertrophy in a rat angiotensin II infusion model of hypertension. METHODS: Rats were chronically infused with a low dose of angiotensin II (83 ng.min-1.rat-1) or vehicle by osmotic minipumps. The polyamine content of the cardiovascular organs and liver was measured by HPLC, and the blood pressure of conscious rats was determined by a tail cuff method. The mesenteric arterial beds were perfusion fixed in situ and medial and luminal cross sectional areas were determined by computer assisted planimetry. Cardiac hypertrophy was assessed by determination of ventricular:body weight ratios. RESULTS: Angiotensin II infusion caused an increased concentration of polyamines in the ventricles and aorta within hours of beginning the infusion, and within days in the mesenteric arteries. Polyamine content of the liver was unaffected. Hypertrophy of the myocardium and mesenteric arteries in association with the increased blood pressure was evident. CONCLUSIONS: A low dose of angiotensin II stimulates an early biochemical marker of growth, the polyamines, in cardiovascular tissues but not in the liver. The increase in tissue polyamines is associated with cardiovascular hypertrophy and the development of hypertension.

Growth inhibition of human vascular smooth muscle cells by fenofibrate: a possible therapy for restenosis.

OBJECTIVE: The aim was to assess the growth inhibitory effect of fibrates on human vascular smooth muscle cells. Restenosis is the most important factor limiting the long term success of invasive vascular interventions and there is as yet no effective preventive treatment. Platelet derived growth factor (PDGF) is considered to be an important growth promoting agent for vascular smooth muscle cells (VSMC) and fenofibric acid (a hypolipidaemic drug) has been reported to be a PDGF antagonist. METHODS: The effect of the fibrate drugs fenofibrate, clofibrate, bezafibrate, and gemfibrozil were examined on the proliferation of cultured human vascular smooth muscle cells derived from saphenous vein (n = 20) and graft stenoses (n = 7). RESULTS: Fenofibrate (100 microM) produced potent inhibition (48%) of VSMC proliferation at a concentration equivalent to that of its circulating metabolite fenofibric acid, but none of the other drugs produced any significant effect on growth. VSMC derived from graft stenoses were equally sensitive to inhibition as saphenous vein derived controls, in contrast to our previous work which reported that graft stenosis derived VSMC were resistant to growth inhibition by the physiological inhibitor heparin. The antiproliferative effect of fenofibrate was independent of inhibition of cellular cholesterol synthesis or toxicity. Fenofibrate inhibited VSMC growth induced by 15% fetal calf serum, PDGF, and basic fibroblast growth factor to a similar degree, indicating that it is not a specific PDGF antagonist. CONCLUSIONS: Fenofibrate is not a specific PDGF antagonist. Fenofibric acid, one of the principal metabolites of fenofibrate, did not produce any inhibition of growth, suggesting that oral administration of fenofibrate would not be efficacious. Fenofibrate is the first potent inhibitor to be described for VSMC derived from human myo-intimal hyperplastic lesions.

Risk of active tuberculosis in chronic kidney disease: a systematic review and meta-analysis.

BACKGROUND: Although the global prevalence of chronic kidney disease (CKD) is increasing, the relationship between CKD and active TB is not well described. OBJECTIVE: To conduct a systematic review to evaluate active TB risk in CKD populations. METHODS: We searched Ovid Medline, EMBASE and Cochrane databases and relevant journals to identify multicentre or regional studies reporting quantitative effect estimates of an association between CKD and active TB. Risk ratios and rate ratios were used as common measures of association. Pooled estimates were generated using a random-effects model. RESULTS: Of 3406 papers screened, 12 eligible studies were identified with 71,374 end-stage renal disease (ESRD) patients and 560 TB cases. Meta-analysis of adjusted rate ratio data in dialysis populations showed an increased rate of 3.62 (95%CI 1.79-7.33, P < 0.001) compared to the general population, while unadjusted risk ratio data in transplant populations showed an increased risk of 11.35 (95%CI 2.97-43.41) compared to the general population. CONCLUSION: We found consistent evidence of an increased risk of active TB in ESRD compared to the general population. This relationship persisted despite variability in study population, design and renal replacement therapy (RRT) modality. Further research into the role of comorbidities, RRT modality and CKD stage is required to better understand the association between CKD and active TB.

Multiple pathways for entry of calcium and other divalent cations in a vascular smooth muscle cell line (A7r5).

The influx of calcium in response to vasopressin receptor stimulation is an important component of excitation-contraction coupling. We have examined the routes by which Ca2+ and other divalent cations enter vascular smooth muscle cells using a cultured vascular smooth muscle cell line (A7r5). Confluent A7r5 cells were loaded with Fura-2 to permit measurement of intracellular divalent cation concentration (Ca2+, Ba2+, Mn2+). Combinations of excitation wavelengths (340/380, 340/356, 356/380 and 340/370) were used depending on the divalent cation being studied. Emission was measured at 510 nm for all studies. Ca2+, Ba2+ and Mn2+ permeated unstimulated A7r5 cells. Vasopressin increased intracellular Ca2+ in cells both in the presence and absence of extracellular Ca2+, although responses in the absence of extracellular Ca2+ were smaller and had no sustained component. Amlodipine, a voltage-dependent calcium channel blocker, had no effect on Ca2+ entry, but Ni2+ did block Ca2+ influx. Vasopressin-induced elevations of intracellular Ca2+ in Ca(2+)-free physiological saline were abolished by ionomycin and thapsigargin. In the presence of extracellular Ba2+ vasopressin increased intracellular Ca2+ transiently and caused a small sustained increase in intracellular Ba2+ concentration. Ionomycin and thapsigargin increased intracellular Ca2+ but had no effect on Ba2+ influx. In contrast vasopressin, ionomycin and thapsigargin had no effect on Mn2+ influx. Econazole and SKF 96365, imidazoles reported to be blockers of receptor-induced cation entry, increased intracellular Ca2+ by releasing intracellular Ca2+ from a different site to that mobilized by vasopressin or thapsigargin in A7r5 cells. Econazole and SKF 96365 partially inhibited passive influx of Ca2+ and Ba2+ but did not inhibit passive influx of Mn2+, or vasopressin-induced influx of Ba2+. U73122, a putative inhibitor of phospholipase C partially inhibited passive entry of Ca2+ but not passive entry of Mn2+ and Ba2+. U73122 also inhibited vasopressin-induced release of intracellular Ca2+ and agonist-induced Ca2+ influx but did not block vasopressin-induced Ba2+ influx. Divalent cations enter A7r5 cells by a number of routes - 'passive' pathway(s) that admit Ca2+, Ba2+ and Mn2+ and receptor-operated pathway(s) that are permeable to Ca2+, Ba2+ but not Mn2+. On the basis of ionic permeabilities and the effect of various blocking agents, there appear to be two distinct passive influx routes. One is permeable to Ca2+ and Ba2+ and is blocked by econazole or SKF 96365. The other is permeable to Mn2+ and is blocked by Ni2+. There also appear to be two different routes of divalent cation entry involved in responses to receptor activation.(ABSTRACT TRUNCATED AT 400 WORDS)

Inhibition of carbonic anhydrase accounts for the direct vascular effects of hydrochlorothiazide.

Hydrochlorothiazide has been shown to exert direct vasodilator effects by activation of calcium-activated potassium (KCa) channels in human and guinea pig isolated resistance arteries. Since hydrochlorothiazide binds to and inhibits the enzyme carbonic anhydrase and because KCa channel activation is pH sensitive, we investigated the role of intracellular and extracellular carbonic anhydrase in the vascular effects of thiazide diuretics. Small arteries were isolated from guinea pig mesentery and studied by use of a microvascular myograph technique. In some experiments, tone and intracellular pH (pHi) were measured simultaneously with 2', 7'-bis(2-carboxyethyl)-5(6)'-carboxyfluorescein (BCECF-AM). Bendroflumethiazide, a thiazide diuretic with minimal inhibitory effects on carbonic anhydrase, had little effect on noradrenaline-induced tone (16+/-8% relaxation) compared with hydrochlorothiazide (74+/-12% relaxation). In contrast to hydrochlorothiazide, the action of bendroflumethiazide was unaffected by 100 nmol/L charybdotoxin, a selective blocker of KCa channels. All inhibitors of carbonic anhydrase relaxed noradrenaline-induced tone in a concentration-dependent manner, and this effect was blocked by charybdotoxin. Hydrochlorothiazide and the inhibitors of carbonic anhydrase failed to relax tone induced by a depolarizing potassium solution. Acetazolamide and hydrochlorothiazide increased pHi by 0.27+/-0.07 and 0.21+/-0.04, respectively, whereas bendroflumethiazide had a much smaller effect: 0.06+/-0.03. The rise in pHi induced by any agent was not inhibited by charybdotoxin. The vasorelaxant effect of hydrochlorothiazide is shared by other inhibitors of carbonic anhydrase. Inhibitors of carbonic anhydrase, but not bendroflumethiazide, cause intracellular alkalinization, which is associated with KCa channel opening. These data suggest that the vasodilator effect of thiazide diuretics results primarily from inhibition of vascular smooth muscle cell carbonic anhydrase, which results in a rise in pHI, leading to KCa channel activation and vasorelaxation.

Characterisation of a high-affinity VIP receptor in human lung parenchyma.

A method is described for preparing human lung parenchymal membranes essentially free of carbon contamination. Using this technique, a high-affinity 125I-VIP-binding site has been characterised. The receptor density is approx. 200 fmol/mg protein, and the Kd of 125I-VIP by saturation binding is 200 pM. The dissociation kinetics are complex and cannot be described by first-order kinetics. Several VIP-related peptides displace 125I-VIP from this binding site with a rank order of potency: VIP greater than rat GRF greater than PHM greater than PHI greater than human GRF greater than secretin greater than glucagon. Displacement curves of these peptides exhibited slope factors significantly less than unity with the exception of human GRF.

Low-density lipoproteins increase intracellular calcium in aequorin-loaded platelets.

Low-density lipoproteins activate isolated human platelets. The mechanism of this activation is unknown, but may involve increased phosphoinositide turnover. We have examined the effect of low-density lipoproteins on intracellular calcium concentrations in platelets loaded with the photoprotein aequorin. The lipoproteins induced concentration-dependent increases in intracellular calcium, associated with shape change and aggregation. These responses could be partially inhibited by the removal of extracellular calcium and by pre-incubation with acetylsalicylic acid. They were also antagonised by agents which increase cellular concentrations of cyclic adenosine and guanosine monophosphates. It is not clear whether the platelet-lipoprotein interaction involves a 'classical' lipoprotein receptor.

Clinical evidence of genomic imprinting in Tourette's syndrome.

Recent genetic studies of Tourette's syndrome (TS) have suggested a sex-specific expression of TS behaviors but not a sex-associated difference in their transmission. In a retrospective study designed to assess the influence of gender of the affected parent on childhood TS phenotype, we compared unmedicated TS subjects with patrilineal (n = 25) or matrilineal (n = 25) inheritance of TS, as determined by family history methodology, with respect to demographic variables, temporal profile of tic evolution, and clinical ratings of tics and associated behaviors, particularly obsessive-compulsive symptoms and attention deficit hyperactivity disorder (ADHD). Maternal transmission of TS was characterized by trends toward greater motor tic complexity and more frequent noninterfering rituals (p < 0.05); paternal transmission was associated with increased vocal tic frequency (p = 0.01), an earlier onset of vocal tics relative to motor tics (p < 0.01), and more prominent ADHD behaviors, including motor restlessness (p < 0.01). These findings are consistent with genomic imprinting in TS. Confirmation of this phenomenon promises not only to advance understanding concerning the genetic link between TS and ADHD but may also help to explain the apparent fit of competing models of genetic transmission in TS.

Electrophysiological evidence for a role of nitric oxide in prolonged chemical nociception in the rat.

The role of nitric oxide in the periphery and the spinal cord, during acute electrically-evoked and prolonged chemically-evoked nociceptive stimulation, was investigated in rats anaesthetised with halothane. The responses of single dorsal horn neurones to electrically-evoked A beta fibre and C fibre inputs were reduced by topical application (directly onto the spinal cord) of both the nitric oxide inhibitor, nitro-L-arginine methyl ester (L-NAME; 500-1500 micrograms) and the precursor of nitric oxide, L-arginine (4500 micrograms). Administration of L-NAME, either directly into the receptive field (500-1500 micrograms) or intravenously (10-100 mg/kg) had little or no effect on the acute electrically-evoked activity. Intravenous injection of L-NAME, administered 40 min prior to injection of formalin, significantly reduced the prolonged second peak of firing, with only a small effect on the short-duration first peak. Administration of L-NAME, directly into the site of injection of formalin, as a 10 min pretreatment, significantly reduced the second but not the first peak of the response. Topical application of L-NAME onto the spinal cord, as a 30 min pretreatment, significantly reduced both the first and second peaks of the response. This inhibition was not reversed by the coadministration of L-arginine, which was inhibitory by itself. Thus, nitric oxide may be involved, in a complex way, in nociceptive events both in the periphery and within the spinal cord.

Inhibition of 5-hydroxytryptamine-mediated behaviour by the putative 5-HT2 antagonist pirenperone.

The effect of pirenperone, a putative 5-HT2 receptor antagonist, on various 5-HT-mediated behavioural responses has been examined. The head twitch response in mice, induced by administration of carbidopa (25 mg/kg) followed by 5-hydroxytryptophan (5-HTP) (200 mg/kg), was inhibited in a dose-dependent manner by pirenperone, with an ED50 of 76 micrograms/kg. The appearance of head weaving, forepaw treading and hind-limb abduction, which followed the administration of tranylcypromine (5 mg/kg) plus L-tryptophan (100 mg/kg) or quipazine (50 mg/kg) to rats, was also inhibited by pretreatment with pirenperone (100 micrograms/kg). Pirenperone did not alter the rate of 5-HT synthesis in the rat brain. Whilst pirenperone (100 micrograms/kg) did decrease methamphetamine-induced locomotor activity in rats, a dose of haloperidol producing a similar inhibition of this response did not alter the 5-HT-mediated behaviour. It is suggested, therefore, that the currently used 5-HT-induced behavioural models are 5-HT2 receptor-mediated.

Effect of angiotension II on the expression of the early growth response gene c-fos and DNA synthesis in human vascular smooth muscle cells.

OBJECTIVES: The aims of this study were to characterize the angiotensin II receptor subtype present on vascular smooth muscle cells from human saphenous vein and to assess the effect of angiotensin II on the expression of the early growth response gene c-fos and on DNA synthesis. METHODS AND RESULTS: Using radioligand binding studies, we have defined the angiotensin II receptors present on these cells as being predominantly of the AT1 subtype. Angiotensin II increased peak intracellular calcium levels by 126 +/- 16 nmol/l (mean +/- SEM) in 17/49 cultures. Angiotensin II induced c-fos expression in a concentration-dependent manner only in cultures that exhibited an intracellular calcium transient in response to stimulation with angiotensin II. The induction of c-fos was inhibited by the selective AT1 antagonist losartan in accordance with the binding studies. Angiotensin II stimulated DNA synthesis with a maximal increase of 66.4% +/- 20.5% over serum-free levels at 1 nmol/l (mean +/- SEM, n = 6, P < 0.05). DNA synthesis declined with increasing angiotensin II concentration, falling to control values at 1 mumol/l, suggesting that a growth-inhibitory influence may counter-balance the stimulatory effect that is observed at lower concentrations. CONCLUSION: Vascular smooth muscle cells from human saphenous vein possess predominantly AT1 receptors and in response to angiotensin II show an induction of c-fos and a modest increase in DNA synthesis.