Analyses of polymorphisms in the inflammasome-associated NLRP3 and miRNA-146A genes in the susceptibility to and tubal pathology of Chlamydia trachomatis infection.

Susceptibility to Chlamydia trachomatis infections is 40% host based. microRNA-146a is a negative regulator of Tolllike receptor (TLR) signaling and possesses functional polymorphisms which decrease the production of premiR-146a and mature miR-146a. Single nucleotide polymorphisms (SNPs) in NLRP3 are associated with decreased NLRP3 expression and hypoproduction of interleukin (IL)-1beta. We investigated whether the SNPs miR-146a G>C (rs2910164), NLRP3 C>T (rs4925663) and G>A (rs12065526) are associated with the susceptibility to and severity of C. trachomatis infection. The genotypes of three SNPs were tested in two cohorts: cohort 1 consists of Dutch women (n = 318) attending a sexually transmitted disease (STD) clinic and cohort 2 (n = 277) consists of subfertile (n = 184) and healthy Finnish women (n=93). While in cohort 1 the analyzed SNPs were not associated with the susceptibility to C. trachomatis infections (C. trachomatis-positive vs. C. trachomatis-negative), we showed in C. trachomatis-positive women that the NLRP3 mutant AG and AA genotypes were a risk factor for the development of symptoms (P = 0.047, OR = 2.9) and more specifically for having lower abdominal pain (genotype AA: P = 0.022, OR = 31.3). In the Finnish tubal pathology group versus the control group no statistical significant differences in the incidences of the SNPs studied were found, nor for the degree of tubal pathology. In conclusion, the mutant NLRP3 A allele is a risk factor for the development of symptoms, specifically lower abdominal pain, after a C. trachomatis infection in women attending an STD clinic.

The inflammatory aspects of Chlamydia pneumoniae-induced brain infection.

The importance of inflammation in the pathogenesis of neurodegenerative diseases, such as Alzheimer's disease, is increasingly being recognized. Although amyloid-beta is considered to be one of the main initiators of these inflammatory processes, some reports suggest that brain infections may also contribute or even initiate the neuroinflammation. One of the best studied pathogens that might be involved in this phenomenon is the herpes simplex virus, but more recently the obligate intracellular respiratory Gram-negative bacterium, Chlamydia pneumoniae, has also been associated with Alzheimer's disease. The present article discusses recent data on the role of C. pneumoniae infection in neuroinflammation and its potential contribution to the pathogenesis of Alzheimer's disease.

Exploring the role of Chlamydia pneumoniae in cardiovascular disease: a narrative review.

An overwhelming number of studies have suggested that Chlamydia pneumoniae infections play a role in the development of atherosclerosis. Several, but not all, seroepidemiological studies have shown that C. pneumoniae antibodies may be related to the development of atherosclerotic disease. Additionally, C. pneumoniae seems to be present in atherosclerotic but not in healthy vascular tissue. Experimental studies have suggested a number of molecular mechanisms by which vascular C. pneumoniae infection might stimulate atherosclerosis development. Alternatively, nonvascular C. pneumoniae infection may cause clinically relevant atherosclerosis-related cardiovascular events through the systemic effects of chronic infection. Genetic variation may account for individual differences in susceptibility to the proatherogenic effects of C. pneumoniae infection. Despite the suggested role of infection in atherosclerosis, antibiotics seem to have no place in the secondary prevention of atherosclerosis-related cardiovascular events. The present narrative review evaluates the role of C. pneumoniae infections in the development of cardiovascular disease.

Inflammatory responses following Chlamydia pneumoniae infection of glial cells.

Recently, infections have been implicated in the pathogenesis of Alzheimer's disease. Apart from the direct effects of pathogens, it can be hypothesized that inflammatory mechanisms, such as the production of pro-inflammatory mediators by resident glia, may result in neurotoxicity. Here, we examined the inflammatory responses in murine microglial cell (MMC) and murine astrocyte cell (MAC) lines following infection with Chlamydia pneumoniae (Cpn), a pathogen that has recently been associated with Alzheimer's disease. Furthermore, we determined whether these inflammatory responses are sufficient to cause neuronal cell death in vitro. MMCs and MACs were infected with Cpn. Subsequently, various chemo- and cytokines were determined in the culture supernatant fluid of infected/control cells at different time points post-infection. Significantly higher levels of monocyte chemoattractant protein 1, interleukin (IL)-6, tumour necrosis factor (TNF)-alpha and IL-1beta were found in supernatant fluids of infected MMCs compared with controls. In contrast, in the supernatant fluid of infected MACs, only monocyte chemoattractant protein 1 and IL-6 displayed significantly higher levels compared with controls. Moreover, neurotoxicity was examined up to 72 h after transferring the conditioned supernatant fluid to a neuronal cell layer. No neuronal cell death was observed when supernatant fluids from infected/mock-treated MACs were transferred. However, when neurones were exposed to conditioned supernatant fluid from infected MMCs, a significant increase in cell death was observed compared with mock. Furthermore, adding neutralizing antibodies against IL-6 and TNF-alpha to that conditioned supernatant fluid prevented neuronal cell death by approximately 50%. In conclusion, these data suggest that Cpn infection results in a pro-inflammatory milieu, particularly by activating MMCs, that ultimately results in neurodegeneration with prominent roles for both IL-6 and TNF-alpha.

Chlamydia pneumoniae infection is not associated with chronic transplant dysfunction in a rat aortic allograft model.

Long-term survival of solid-organ transplants is limited as a result of chronic transplant dysfunction (CTD), which is characterized by occlusion of intragraft vascular tissue due to myointimal hyperplasia. Recent studies have shown a role for infections in vascular pathologies. For example, Chlamydia pneumoniae (Cpn) has been shown to aggravate atherosclerosis, and Cpn immunoglobulin (Ig)G titers correlate with severity of allograft atherosclerosis after cardiac transplantation. In this study, we evaluated the effect of Cpn infection on CTD using a rat aortic allograft model. Orthotopic abdominal aorta transplantations (Tx) were performed with Brown Norway rats as donors and Lewis rats as recipients. Rats were humanely killed at 1 or 8 weeks after surgery. The graft was processed for DNA isolation and histological examination. Influx of macrophages and T cells was assessed using immunohistochemistry. At 1 week after Tx, the perivascular influx of inflammatory cells in the graft was not affected by Cpn infection. Furthermore, only limited numbers of Cpn DNA copies were found in the graft at 1 week after Tx. In addition, Cpn did not alter the severity of myointimal hyperplasia in the rat aortic allograft model at 8 weeks after surgery. Our data suggested that, in the rat aortic allograft model, Cpn infection did not influence the influx of inflammatory cells or the severity of CTD.

Chlamydia pneumoniae infections augment atherosclerotic lesion formation: a role for serum amyloid P.

Multiple reports have demonstrated an association between Chlamydia pneumoniae (Cpn) and cardiovascular disease. In this study we evaluated the effect of Cpn infections on early lesion progression in C57BL/6J mice. Since plaque formation in these mice does not develop past the initial stage, we thought these mice might be a better model for unravelling the effect of Cpn infection on early lesion type progression. C57BL/6J mice were fed an atherogenic diet and injected 10 times with 5 x 10(7) IFU Cpn or mock. At sacrifice, lesion number, size and type were analysed. To study the role of Cpn in inflammation, serum amyloid P (SAP) in plasma was determined as well as T-cells, macrophages and SAP in the lesions. In the aortic sinus of both groups, type 2 lesions were found. Cpn infection resulted in a 2.2-fold increase in total lesion size (Cpn: 10821+/-2429 microm(2)vs mock: 5022+/-1348 microm(2); p=0.04). No difference in lesion number was observed. Also, Cpn infection increased SAP in the lesions from 1.10(-4)+/-0.1.10(-4) SAP-positive cells/lesion area to 10.10(-4)+/-1.10(-4) SAP-positive cells/lesion area (p=0.05). The influx of T-lymphocytes and macrophages in the lesions as well as SAP plasma levels were not different between groups. Multiple Cpn infections resulted in a significant increase in total lesion size of C57BL/6J mice. Increase in total SAP-positive area in infected mice suggests a role for this acute-phase protein in lesion enlargement.

Delivery of Chlamydia pneumoniae to the vessel wall aggravates atherosclerosis in LDLr-/- mice.

OBJECTIVE: The role of Chlamydia pneumoniae in atherosclerosis is still debated. In this study a novel mouse model was applied to determine the direct impact of C. pneumoniae on the arterial wall and the development of atherosclerosis. METHODS: Direct effects of C. pneumoniae on collar-induced atherosclerosis were studied after local delivery of C. pneumoniae to carotid arteries of LDL receptor-deficient (LDLr-/-) mice. RESULTS: The presence of C. pneumoniae in the vessel wall was quantified by RT-PCR (6.2 x 10(4) copies/artery) and resulted in a 2.0-fold increase in intima/media ratios (p<0.05) and a 1.7-fold increase in stenosis (p<0.05). Immunostaining revealed a 2.98-fold (p<0.01) increased macrophage content and a tendency towards lower numbers of smooth muscle cells and collagen in lesions of infected carotid arteries. Direct delivery of another respiratory pathogen, Mycoplasma pneumoniae, to the carotids did not affect size or composition of the atherosclerotic lesions. Presence of C. pneumoniae in the carotid arteries resulted within 7 days in a marked upregulation of the expression of MCP-1 (p<0.01) and ICAM-1 as determined on mRNA and protein levels. These in vivo data were in line with data obtained with in vitro infections of macrophages and endothelial cells with C. pneumoniae. CONCLUSIONS: We conclude that C. pneumoniae in carotid arteries leads to more pronounced atherosclerotic lesions with a more vulnerable morphology and that this model is suitable to monitor direct effects of C. pneumoniae on atherogenesis.

Secondary prevention of atherosclerosis through chlamydia pneumoniae eradication (SPACE Trial): a randomised clinical trial in patients with peripheral arterial disease.

BACKGROUND: Sero-epidemiological and experimental studies suggest that Chlamydia pneumoniae infections play an important role in the development of atherosclerosis. Clinical trials have shown contradictory results regarding the efficacy of antibiotics to prevent atherosclerosis-related complications in patients with coronary artery disease. Our aim was to study the effect of a short course of azithromycin on the incidence of cardiovascular events and peripheral vascular function in patients with stable peripheral arterial disease (PAD). PATIENTS AND METHODS: Five hundred and nine PAD-patients were randomised to receive either a 3-day course of azithromycin (500 mg daily) or placebo, with 2 years of follow-up. C. pneumoniae serology was determined at baseline. Clinical endpoints were death, coronary events (myocardial infarction, unstable angina, and/or coronary revascularization procedures), cerebral events (stroke, TIA, and/or carotid endarterectomy) and peripheral arterial complications (increased PAD-symptoms with decreased ankle-brachial index (ABPI, 0.1-point decrease after 12 months), and/or peripheral revascularization procedures). RESULTS: Five hundred and nine patients (160 women) with an atherosclerotic risk factor profile were randomised, 257 patients to azithromycin and 252 to placebo. Four hundred and forty nine patients (88%) had intermittent claudication and 60 (12%) had critical limb ischemia. By 24-month follow up, 182 patients (36%) developed 252 complications (45 deaths, 34 coronary events, 34 cerebral events and 139 peripheral arterial complications). C. pneumoniae IgA-titres were associated with the development of cardiovascular events. Nevertheless, the number of complications (131 in the azithromycin group vs. 121 in the placebo group) and the number of patients that developed complications (98 (38%) in the azithromycin vs. 84 (33%) in the placebo group) was comparable in both treatment groups. Life table analysis showed no effect of azithromycin on survival or ABPI. CONCLUSION: A short-term course of azithromycin offers no benefits for survival or ankle pressure in PAD-patients.

Serological markers of persistent C. trachomatis infections in women with tubal factor subfertility.

BACKGROUND: Persistent C. trachomatis infections are assumed to increase the risk of tubal pathology. We studied whether serological markers, assumed to be associated with persistent C. trachomatis infections, could identify subfertile women at risk of tubal pathology. METHODS: Sera of 313 subfertile women, who all underwent a laparoscopy with tubal testing to assess the grade of tubal pathology, were tested for the presence of immunoglobulin (Ig) G and IgA antibodies to C. trachomatis, IgG antibodies to chlamydia heat shock protein 60 (cHSP60) and C-reactive protein (CRP). RESULTS: C. trachomatis IgA, cHSP60 IgG and CRP, all serological markers of persistent infections, were significantly more prevalent in women with tubal pathology as compared to those without tubal pathology. The predictive value of the currently used screening test for tubal pathology (IgG to C. trachomatis) could be significantly improved by adding the CRP test. CONCLUSIONS: In subfertile women with tubal pathology, serological markers of persistent C. trachomatis infections are significantly more common as compared to women without tubal pathology. C. trachomatis IgG-positive subfertile women with slightly elevated (< 10 mg/l) CRP levels are at highest risk of persistent C. trachomatis infections and tubal pathology.

The role of chlamydia genus-specific and species-specific IgG antibody testing in predicting tubal disease in subfertile women.

BACKGROUND: We evaluated whether measuring chlamydia genus- and species-specific immunoglobulin (Ig) G antibodies might improve the predictive value of C. trachomatis antibody testing (CAT) in screening for distal tubal pathology (DTP). METHODS: Serum of 313 subfertile women was tested for the presence of species-specific antibodies to C. trachomatis, C. pneumoniae and C. psittaci and genus-specific antibodies to chlamydia lipopolysaccharide (LPS). Only patients who had undergone a laparoscopy with tubal testing, to assess the grade of DTP, were included in this study. RESULTS: The presence of C. trachomatis antibodies was the only independent predictor for DTP. The predictive value of CAT for DTP could not be improved by adding test results of C. pneumoniae or LPS antibody testing. The role of C. psittaci could not be evaluated, due to the absence of C. psittaci-positive patients in our cohort. CONCLUSIONS: In spite of the high interspecies homology, C. pneumoniae does not contribute to the development of DTP. Anti-LPS antibodies, which are considered to be markers for ongoing infections, do not identify C. trachomatis-positive subfertile women who are at highest risk of DTP. The high prevalence of anti-LPS antibodies in C. trachomatis-positive subfertile women may suggest that C. trachomatis remains more active in the upper genital tract than currently is presumed.

Chlamydia pneumoniae infection induces an unstable atherosclerotic plaque phenotype in LDL-receptor, ApoE double knockout mice.

OBJECTIVES: To study whether Chlamydia pneumoniae (Cpn) infection affects atherosclerotic plaque morphology in atherogenic (LDLr/ApoE(-/-)) mice. METHODS: In mice sacrificed 20 or 40 weeks after Cpn infection aortic arch sections were analysed for lesion and fibrous cap area and the presence of matrix metalloproteinases (MMP)-2 and -9. RESULTS: All infected mice seroconverted, demonstrated Cpn DNA in their aortas on PCR and developed atherosclerotic plaques. Infection was not associated with changes in lesion area or type, but was associated with reduced the fibrous cap area and increased MMP-2 and -9 immunoreactivity. CONCLUSION: These findings suggest that Cpn infection may predispose to plaque instability.

Chlamydophila pneumoniae (Chlamydia pneumoniae) accelerates the formation of complex atherosclerotic lesions in Apo E3-Leiden mice.

OBJECTIVE: Atherosclerosis is an inflammatory process and is characterised by the presence of T-lymphocytes in the lesions. To study the role of Chlamydophila pneumoniae (C. pneumoniae) in this process and the effect of infection on T-cell influx, we infected Apo E3-Leiden mice with C. pneumoniae and investigated the effect on lesion development and T-cell influx in atherosclerotic lesions at different time points post infection (pi). METHODS: Nine week old mice, fed an atherogenic diet, were either mock-infected or infected with C. pneumoniae and sacrificed at 1, 6 and 9 months pi. Longitudinal sections of the aortic arches of the mice were stained with hematoxylin-eosin for atherosclerotic lesion type and lesion area analysis, or with rabbit-anti-CD3(+) to detect the presence of T-cells in the atherosclerotic lesions. T-cell influx was expressed as number of T-lymphocytes/lesion area. RESULTS: At 1 month pi, type 1, 2 and 3 lesions were present. At other time points pi, more complex lesion types 4, 5a and 5b were also present. Although infection did not influence the total lesion number or area, we observed an effect of C. pneumoniae infection on lesion type. Infection resulted in a significant shift in lesion formation from type 3 to type 4 (P=0.022) at 6 months pi, and from type 4 to type 5a (P=0.002) at 9 months pi. T-cells were observed at every time point pi. At 1 month pi, a significant increase in T-cell influx in the C. pneumoniae-infected atherosclerotic lesions was observed (P=0.0005). CONCLUSION: This study shows that C. pneumoniae infection enhances the inflammatory process by increasing T-lymphocytes in the plaque and accelerates the formation of complex lesions.

Angiogenesis and hypertension.

BACKGROUND: The formation of new blood vessels is an important process in embryonic development and in physiological repair processes. Abnormalities in blood vessel growth have been associated with various pathologies. HYPERTENSION AND IMPAIRED VASCULAR GROWTH: The basic observation underlying the hypothesis that essential hypertension is based on an impaired capacity for vascular growth is the nature of the structural alterations of microvascular beds in essential hypertension. Recent advances in understanding the molecular and cellular mechanisms of vascular growth suggest that the remodeling of individual vessels and vascular networks in hypertension may be a pathological variant of the formation of mature networks. PATHOGENESIS OF IMPAIRED VASCULAR GROWTH: Genetic and fetal influences appear to have significant effects in determining impaired vascular development as an early cause of essential hypertension.

A positive and reversible relationship between adrenergic nerves and alpha-1A adrenoceptors in rat arteries.

We evaluated the relationship between the presence of adrenergic nerves and the presence of alpha-1 adrenoceptors (alpha-1 AR) in the arterial tree of the rat. The thoracic aorta and the carotid, mammary, renal and femoral arteries were isolated from 20-week-old male WKY rats, along with the superior mesenteric artery and small (first order) and resistance-sized (third order) side branches of this vessel. Norepinephrine content ([NE]) and specific binding of 300 pM [3H]prazosin were determined. To estimate the total density of alpha-1 AR ([alpha-1 AR]) as well as the density of alpha-1A AR ([alpha-1A AR]), binding experiments were performed with and without pretreatment of the preparations with the irreversible alpha-1B AR and alpha-1D AR antagonist chloroethylclonidine and in the absence and presence of the alpha-1A AR selective ligand (+)-niguldipine (30 nM). Also the presence of mRNA for alpha-1A AR was evaluated by use of reverse transcriptase-polymerase chain reaction (RT-PCR). In intact rats, arterial [NE] ranged between 0.1 and 15 ng/microgram DNA, arterial [alpha-1 AR] ranged between 12.4 and 46.8 fmol/mg protein and [alpha-1A AR] ranged between 0.05 and 27.9 fmol/mg protein. There was no significant correlation between [alpha-1 AR] and [NE]. However, with respect to the [alpha-1A AR] a significant correlation between [NE] and [alpha-1A AR] was observed. RT-PCR analysis confirmed the expression of alpha-1A AR in the densely innervated mesenteric resistance-sized arteries. Two weeks after chemical sympathectomy of the rats with 6-hydroxydopamine (i) arterial [NE] was markedly reduced, and (ii) a distinct reduction in the [alpha-1A AR] as percentage of the total [alpha-1 AR] density in mesenteric artery side branches was noted. These findings indicate that there is a positive and reversible relationship between the presence of adrenergic nerves and that of alpha-1A AR in rat arteries.

Angiotensin II induces media hypertrophy and hyperreactivity in mesenteric but not epigastric small arteries of the rat.

We examined effects of a 2-week infusion of angiotensin II (AII, 250 ng x kg[-1] x min[-1]) on properties of mesenteric resistance arteries (MrA) and superior epigastric arteries (SEA) of male Wistar rats. Histochemistry and pharmacological tools showed that MrA are densely innervated, whereas SEA are only sparsely innervated. AII infusion resulted in a significant elevation in mean arterial pressure and in plasma AII and noradrenaline levels. Organ chamber studies and morphometry were used to determine arterial contractile reactivity and structure. After AII infusion, in MrA (i) maximal contractile responses to 125 mM K+, noradrenaline, serotonin and adrenergic nerve stimulation were significantly increased, without modification of the sensitivity to these stimuli and (ii) a significant increase in media cross-sectional area and media thickness was observed without alterations in lumen diameter. The observed increase in vascular reactivity could fully be attributed to the observed increase in wall mass since no alterations in maximal active wall stress were noted. In SEA, no significant changes in responsiveness to vasoconstrictor stimuli or in wall structure were observed. These findings suggest that perivascular nerves are involved in the hypertrophy and subsequent hyperreactivity of small arteries in rats exposed for 2 weeks to a low dose of AII.

Coronary arterial hyperreactivity and mesenteric arterial hyporeactivity after myocardial infarction in the rat.

After myocardial infarction, several neurohumoral systems become activated to maintain systemic perfusion pressure. We evaluated whether this leads to alterations of wall structure and contractile reactivity in the thoracic aorta, coronary septal artery, and mesenteric resistance arteries. In male Wistar rats, myocardial infarction (MI) was induced by permanent ligation of the left coronary artery. At 5 weeks after MI or sham operation, vessel segments were isolated, chemically sympathectomized, and mounted in a myograph for recording of isometric force development. Contractile reactivity to high potassium, norepinephrine, phenylephrine, serotonin, and Arg-vasopressin was determined. At the end of the experiments, vessels were fixed for morphometric analysis (cross-sectional area, media thickness, radius, and wall-to-lumen ratio). At 5 weeks after myocardial infarction, no alterations of contractile reactivity or wall structure were observed in the thoracic aorta of MI rats. In mesenteric resistance arteries, a nonselective reduction of maximal active wall tension and of active wall stress in response to vasoconstrictors was observed, whereas vessel wall structure and sensitivity to stimuli were not modified. On the other hand, coronary septal arteries displayed hyperreactivity to all strong contractile stimuli. These observations demonstrate a heterogeneity of arterial reactivity changes at 5 weeks after MI in the rat: (a) no alterations in thoracic aorta, (b) hyporeactivity of mesenteric resistance arteries despite maintenance of media mass, and (c) hyperreactivity of coronary vessels obtained from the hypertrophic remnant myocardium. This could result from the complex regional hemodynamic and neurohumoral changes associated with heart failure and may contribute to the further deterioration of cardiovascular function in this setting.

Reduced responsiveness of rat mesenteric resistance artery smooth muscle to phenylephrine and calcium following myocardial infarction.

1. We evaluated responses of peripheral resistance arterial smooth muscle to alpha 1-adrenoceptor stimulation in a rat model of heart failure in relation to neurohumoral changes, wall structure, receptor density and cellular calcium handling. 2. Plasma samples and third order mesenteric artery side-branches were obtained from Wistar rats after induction of left ventricular infarction (M1) or sham surgery. Vessels were denuded of endothelium, sympathectomized, depleted of neuropeptides, and mounted in a myograph for recording of isometric force development in response to calcium, agonist and high potassium. Also, the morphology of these preparations was determined. Separate vessel segments were used in radioligand binding assays with [1H]-prazosin. 3. At 1 week after MI, circulating plasma levels of adrenaline, angiotensin II, atrial natriuretic factor (ANF) and vasopressin were significantly elevated. At 5 weeks only a significant elevation of ANF persisted. 4. At 5 weeks after MI, the structure of the vessels and responsiveness to high potassium or Bay K 8466 (10(6) mol l-1) were not modified. Yet, at this stage, sensitivity to phenylephrine was increased (pD2: 6.24 +/- 0.04 vs 5.98 +/- 0.04 for controls) while maximal contractile responses to phenylephrine in the presence of 2.5 mmol l-1 calcium (2.26 +/- 0.28 vs 3.53 +/- 0.34 N m-1) and the sensitivity to calcium in the presence of phenylephrine (pD2: 2.81 +/- 0.22 vs 3.74 +/- 0.16) were reduced. Responses to the agonist in calcium-free solution and the calcium sensitivity in the presence of 125 mmol l-1 potassium or of phorbol myristate acetate (PMA, 10(-6) mol l-1) were not altered. 5. At 5 weeks after MI, the density of prazosin binding sites was not reduced (4.04 +/- 1.40 vs 2.29 +/- 0.21 fmol microgram-1 DNA in controls). 6. In conclusion, myocardial infarction leads in the rat to a reduction of contractile responses of mesenteric resistance arterial smooth muscle to alpha 1-adrenoceptor stimulation. This seems to involve impaired agonist-stimulated calcium influx.

Alpha 1-adrenoceptor subtypes in rat aorta and mesenteric small arteries are preserved during left ventricular dysfunction post-myocardial infarction.

OBJECTIVE: In heart failure, homologous downregulation of beta-adrenoceptors contributes to impaired adrenergic responsiveness of the myocardium. We evaluated alpha 1-adrenoceptors (alpha 1-AR) in a sparsely innervated and a densely innervated peripheral artery in an experimental model of left ventricular dysfunction post-myocardial infarction. METHODS: [3H]Prazosin binding was determined in arterial segments of Wistar-Kyoto rats (WKY), and of Wistar rats 5 weeks after myocardial infarction (MI) or sham operation (SHAM). RESULTS: In the thoracic aorta (TAO) of WKY, specific prazosin binding was: (i) prevented by the irreversible alpha 1B-AR and relatively selective alpha 1D-AR antagonist, chloroethylclonidine (CEC); (ii) displaced with low affinity (pKi 6.25) by the alpha 1A-AR selective ligand, (+)-niguldipine; and (iii) displaced with both high (pKi 10.4) and low (pKi 7.37) affinity by the alpha 1D-AR antagonist, BMY 7378. In mesenteric small arteries (MSA) of WKY, prazosin binding was: (i) reduced 50% by CEC; (ii) displaced in a biphasic fashion by (+)-niguldipine (pKi 8.60 and pKi 6.22); and (iii) displaced by BMY 7378 with low affinity only (pKi 6.86). Also in TAO of SHAM. prazosin binding was prevented by CEC, but neither 30 nM (+)-niguldipine nor 1 nM BMY 7378 affected it. In MSA of SHAM, prazosin binding was virtually abolished in the presence of 30 nM (+)-niguldipine and was not reduced by 1 nM BMY 7378. In TAO and MSA of MI, compared to SHAM, the density of binding sites tended to be increased rather than decreased and neither the affinity for the ligand nor the effects of alpha 1-AR subtype selective tools were significantly modified. CONCLUSIONS: These findings indicate that: (i) radioligand binding can be applied in intact arterial segments to quantify and characterize alpha 1-AR; (ii) although differences seem to exist between rat strains, alpha 1B-AR and alpha 1D-AR predominate in rat thoracic aorta and alpha 1A-AR and alpha 1B-AR in mesenteric small arteries; and (iii) alpha 1-AR density is not reduced in the poorly innervated aorta and the densely innervated mesenteric small arteries of rats with heart failure due to myocardial infarction.

High energy phosphates and related compounds, glycogen levels and histology in the rat tibialis anterior muscle after forced lengthening and isometric exercise.

Eccentric exercise may elicit damage to the contractile elements. This primary damage is followed by secondary changes, consisting of histological changes and changes in glycogen and energy metabolism. The mechanism underlying changes in glycogen homeostasis and energy metabolism is not well established. The aim of this study was to investigate the possible relationship between changes in adenine and guanine nucleotides, inosine monophosphate (IMP), creatine phosphate, glycogen content and histology in the rat tibialis anterior (TA) muscle after forced lengthening or isometric exercise. The right muscles were either forcibly lengthened or isometrically exercised, while the contralateral muscles served as non-exercised controls. The exercised muscles were dissected 0, 6 and 24 h post-exercise and the contents of adenine and guanine nucleotides, IMP, creatine phosphate, and glycogen determined. In addition, histological changes were assessed. Immediately after both types of exercise increases in tissue IMP levels were found. Irrespective of the type of exercise, glycogen content was decreased immediately post-exercise, but restored 6 h post-exercise. Twenty-four hours later a second decline in glycogen content was found after both types of exercise. In forcibly lengthened muscles ATP content was decreased 24 h post-exercise. In isometrically exercised muscles ATP was not decreased at any time. Gross structural changes were found in all forcibly lengthened muscles (9-12% of TA muscle volume). In isometrically exercised muscles structural changes were minor (up to 0.1% of muscle volume), were found only immediately post-exercise and in only 4 out of 18 muscles. It is concluded that forced lengthening results in decreased ATP levels.(ABSTRACT TRUNCATED AT 250 WORDS)