Enalapril Is Superior to Lisinopril in Improving Endothelial Function without a Difference in Blood-Pressure-Lowering Effects in Newly Diagnosed Hypertensives.

Angiotensin-converting enzyme (ACE) inhibitors are the primarily chosen drugs to treat various cardiovascular diseases, such as hypertension. Although the most recent guidelines do not differentiate among the various ACE inhibitory drugs, there are substantial pharmacological differences. GOAL: Here, we tested if lipophilicity affects the efficacy of ACE inhibitory drugs when used as the first therapy in newly identified hypertensives in a prospective study. METHODS: We tested the differences in the cardiovascular efficacy of the hydrophilic lisinopril (8.3 ± 3.0 mg/day) and the lipophilic enalapril (5.5 ± 2.3 mg/day) (n = 59 patients). The cardiovascular parameters were determined using sonography (flow-mediated dilation (FMD) in the brachial artery, intima-media thickness of the carotid artery), 24 h ambulatory blood pressure monitoring (peripheral arterial blood pressure), and arteriography (aortic blood pressure, augmentation index, and pulse wave velocity) before and after the initiation of ACE inhibitor therapy. RESULTS: Both enalapril and lisinopril decreased blood pressure. However, lisinopril failed to improve arterial endothelial function (lack of effects on FMD) when compared to enalapril. Enalapril-mediated improved arterial endothelial function (FMD) positively correlated with its blood-pressure-lowering effect. In contrast, there was no correlation between the decrease in systolic blood pressure and FMD in the case of lisinopril treatment. CONCLUSION: The blood-pressure-lowering effects of ACE inhibitor drugs are independent of their lipophilicity. In contrast, the effects of ACE inhibition on arterial endothelial function are associated with lipophilicity: the hydrophilic lisinopril was unable to improve, while the lipophilic enalapril significantly improved endothelial function. Moreover, the effects on blood pressure and endothelial function did not correlate in lisinopril-treated patients, suggesting divergent mechanisms in the regulation of blood pressure and endothelial function upon ACE inhibitory treatment.

The feasibility of baroreflex sensitivity measurements in heart failure subjects: The role of slow-patterned breathing.

INTRODUCTION: Increased muscle sympathetic nerve activity (MSNA) indicates an adverse outcome in heart failure. Decreased baroreflex modulation of MSNA is a well-known feature of the disease. The determinability of cardiovagal baroreflex sensitivity (BRS) in heart failure is low, however, the determinability of sympathetic BRS is not known. METHODS: We have assessed the spontaneous, MSNA burst incidence-based baroreflex index (BRSsymp) in 33 stable heart failure patients and in 10 healthy controls using the traditional r ≥ .5 cutoff for acceptable individual diastolic pressure-burst incidence slopes, and also a more stringent r ≥ .7 cutoff. We have also assessed the influence of 6/min breathing. RESULTS: The determinability of BRSsymp in heart failure patients was 64% during spontaneous breathing with r ≥ .5 cutoff, and 39% using the r ≥ .7 cutoff. The determinability of these indices further decreased during 6/min breathing, dropping to 29% with the r ≥ .7 cutoff. In contrast, the determinability of the cardiovagal BRS indices increased significantly with 6/min breathing (from 24% to 66%; p < .001). Patients who still had determinable BRSsymp at the r ≥ .7 cutoff had a significantly lower baseline burst incidence than those with an undeterminable index (70 ± 14 vs. 89 ± 10 burst/100 cycles; p < .002). Neither the 6/min breathing, nor the r ≥ .7 cutoff limit influenced the high availability of BRSsymp in healthy subjects. CONCLUSION: The determinability of BRSsymp in heart failure patients is limited, especially with the 0.7 limit for correlation. Undeterminable BRSsymp in patients is associated with higher sympathetic activity. 6/min breathing improves the determinability of cardiovagal BRS indices, but not that of BRSsymp.

Changes in the SARS-CoV-2 cellular receptor ACE2 levels in cardiovascular patients: a potential biomarker for the stratification of COVID-19 patients.

Angiotensin-converting enzyme 2 (ACE2) is essential for SARS-CoV-2 cellular entry. Here we studied the effects of common comorbidities in severe COVID-19 on ACE2 expression. ACE2 levels (by enzyme activity and ELISA measurements) were determined in human serum, heart and lung samples from patients with hypertension (n = 540), heart transplantation (289) and thoracic surgery (n = 49). Healthy individuals (n = 46) represented the controls. Serum ACE2 activity was increased in hypertensive subjects (132%) and substantially elevated in end-stage heart failure patients (689%) and showed a strong negative correlation with the left ventricular ejection fraction. Serum ACE2 activity was higher in male (147%), overweight (122%), obese (126%) and elderly (115%) hypertensive patients. Primary lung cancer resulted in higher circulating ACE2 activity, without affecting ACE2 levels in the surrounding lung tissue. Male sex resulted in elevated serum ACE2 activities in patients with heart transplantation or thoracic surgery (146% and 150%, respectively). Left ventricular (tissular) ACE2 activity was unaffected by sex and was lower in overweight (67%), obese (62%) and older (73%) patients with end-stage heart failure. There was no correlation between serum and tissular (left ventricular or lung) ACE2 activities. Neither serum nor tissue (left ventricle or lung) ACE2 levels were affected by RAS inhibitory medications. Abandoning of ACEi treatment (non-compliance) resulted in elevated blood pressure without effects on circulating ACE2 activities. ACE2 levels associate with the severity of cardiovascular diseases, suggestive for a role of ACE2 in the pathomechanisms of cardiovascular diseases and providing a potential explanation for the higher mortality of COVID-19 among cardiovascular patients. Abandoning RAS inhibitory medication worsens the cardiovascular status without affecting circulating or tissue ACE2 levels.

Sympathetic activation in heart failure with reduced and mildly reduced ejection fraction: the role of aetiology.

AIM: While sympathetic overactivity in heart failure (HF) with reduced ejection fraction (HFrEF; EF < 40%) is well-documented, it is ill-defined in patients with mildly reduced EF (HFmrEF; EF 40-49%). Furthermore, the significance of ischaemic versus non-ischaemic aetiology in sympathetic activation is also unclear and has yet to be studied in HF. Our goal was to compare muscle sympathetic nerve activity (MSNA) in HFmrEF and HFrEF patients and in healthy subjects, as well as to elucidate the influence of the underlying disease. METHODS AND RESULTS: Twenty-three HFrEF (age 58 ± 10 years), 33 HFmrEF patients (age 61 ± 10 years), including 11 subjects with non-ischaemic cardiomyopathy in each HF groups and 10 healthy controls (age 55 ± 10 years), were studied. MSNA-detected by peroneal microneurography, continuous arterial pressure, and ECG-was recorded. MSNA frequency (burst/min) and incidence (burst/100 cycles) were calculated. Association with the patients' characteristics were assessed, and aetiology-based comparisons were performed. Burst frequency demonstrated a significant stepwise increase in both HFmrEF (41 ± 11 burst/min) and HFrEF (58 ± 17 burst/min, P < 0.001) patients as compared with controls (27 ± 9; P < 0.001 for both HF groups). Similarly, burst incidences were 66 ± 17, 82 ± 15, and 36 ± 10 burst/100 cycles in HFmrEF, HFrEF patients, and in healthy controls, respectively (P < 0.001 for all). Burst frequencies in HF patients showed significant correlation with NT-proBNP levels, and significant inverse correlations with the subjects' mean RR intervals, stroke volumes, pulse pressures, and EF. CONCLUSIONS: Muscle sympathetic nerve activity parameters indicated significant sympathetic activation in both HFmrEF and HFrEF patients as compared with healthy controls with no difference in relation to ischaemic versus non-ischaemic aetiology.

[Consensus statement of the Hungarian Clinical Neurogenic Society about the therapy of adult SMA patients]. / A Magyar Klinikai Neurogenetikai Társaság konszenzusajánlása a felnottkori spinalis izomatrophia (SMA) kezeléséhez.

BACKGROUND AND PURPOSE: Background - Spinal muscular atrophy (SMA) is an autosomal recessive, progressive neuromuscular disorder resulting in a loss of lower motoneurons. Recently, new disease-modifying treatments (two drugs for splicing modification of SMN2 and one for SMN1 gene replacement) have become available. Purpose - The new drugs change the progression of SMA with neonatal and childhood onset. Increasing amount of data are available about the effects of these drugs in adult patients with SMA. In this article, we summarize the available data of new SMA therapies in adult patients. METHODS: Methods - Members of the Executive Committee of the Hungarian Clinical Neurogenetic Society surveyed the literature for palliative treatments, randomized controlled trials, and retrospective and prospective studies using disease modifying therapies in adult patients with SMA. Patients - We evaluated the outcomes of studies focused on treatments of adult patients mainly with SMA II and III. RESULTS: In this paper, we present our consensus statement in nine points covering palliative care, technical, medical and safety considerations, patient selection, and long-term monitoring of adult patients with SMA. CONCLUSION: This consensus statement aims to support the most efficient management of adult patients with SMA, and provides information about treatment efficacy and safety to be considered during personalized therapy. It also highlights open questions needed to be answered in future. Using this recommendation in clinical practice can result in optimization of therapy.

Cardiovagal and sympathetic baroreflex regulation in heart failure / Cardiovagalis és szimpatikus artériás baroreflex szabályozásának vizsgálata szívelégtelenségben.

Összefoglaló. Bevezetés: Az artériás baroreflex-érzékenységi (BRS-) indexek egységnyi nyomásváltozásra adott élettani válaszokat írnak le. Az RR-intervallum gyors válaszait a cardiovagalis BRS-indexekkel, a vasomotorválaszokat az izom szimpatikus idegi aktivitás (MSNA) válaszain alapuló szimpatikus-BRS-indexekkel jellemezzük. Szívelégtelenségben kórosan csökkent értékeik kedvezotlen kimenetelt jeleznek. Betegek és módszerek: A BRS-indexek meghatározhatóságát 52, szívelégtelenségben szenvedo betegben (kor: 59 ± 10 év; EF: 37 ± 11%) és 11, kor szerint illesztett egészséges önkéntesben vizsgáltuk. EKG- és vérnyomásfelvételekbol három cardiovagalis BRS-indexet számítottunk; a növekvo, illetve csökkeno spontán szekvenciák módszerén alapuló up-BRS-t és down-BRS-t, továbbá az alacsony frekvenciatartomány-beli 'cross-spectralis ' indexet, az LF-alfát. Egy perifériás ideg (nervus peroneus) perkután punkciójával detektáltuk az MSNA szimpatikus csúcs incidenciáját (csúcs/100 szívciklus), s ezt korreláltattuk a diastolés nyomás 3 Hgmm sávokba rendezett értékeivel. Így nyertük a szimpatikus BRS jellemzoit, a BRSSY-incidencia-értékeket. Eredmények: Az up- és down-BRS-szekvenciák csak a betegek 19%-ában voltak meghatározhatók, az LF-alfa a 69%-ukban. Azok, akiknél cardiovagalis BRS nem volt meghatározható, szignifikánsan csökkent RR-intervallum-ingadozást és magasabb NT-proBNP-értékeket mutattak. A meghatározható cardiovagalis BRS-indexek nem különítették el a betegeket és a kontrollszemélyeket. A BRSSY-incidencia-érték 58%-ban állt rendelkezésre, s csakúgy, mint maga a "csúcs" incidencia, jól elkülönítette a betegeket és az önkénteseket. A hiányzó baroreflexérték a magas "csúcs" incidenciával állt összefüggésben. Következtetés: A cardiovagalis BRS-értékek csak korlátozottan alkalmasak egészséges önkéntesek és szívelégtelen betegek elkülönítésére, a meghatározhatatlan értékek súlyosabb betegségre utalnak. A BRSSY-incidencia elkülöníti az egészséges és a beteg csoportokat; a hiányzó érték a fokozott szimpatikus aktivitással áll összefüggésben. Orv Hetil. 2021; 162(3): 91-98. INTRODUCTION: Arterial baroreflex sensitivity (BRS) is characterized by the magnitude of physiological responses to arterial pressure changes. Rapid RR interval responses are quantified by cardiovagal BRS parameters, sympathetic responses could be assessed by changes in muscle sympathetic nerve activity (MSNA). Abnormal indices in heart failure are associated with poor outcome. PATIENTS AND METHODS: 52, heart failure patients (age 59 ± 10 years, EF 37 ± 11%), and 11, age-matched healthy volunteers were studied. From ECG and arterial pressure recordings up-BRS and down-BRS values were determined using the method of spontaneous sequences. The low frequency cross-spectral gain, the LF alpha was also determined. Percutaneous puncture of the peroneal nerves allowed determination of MSNA burst incidence (burst/100 cycles), which was correlated to corresponding diastolic pressure bins of 3 mmHg, yielding a sympathetic BRS, the BRSSY-incidence. RESULTS: Up- and down-BRS could be calculated in 19% of the patients, LF alpha was determined in 69%. Those with missing cardiovagal BRS values showed diminished RR interval variation, and higher levels of NT-proBNP. The measurable cardiovagal BRS indices did not separate patients and healthy volunteers. BRSSY-incidence could be determined in 58% of the patients. The sympathetic gain as well as the burst incidence differed significantly between patients and healthy volunteers. Missing BRSSY-incidence was associated with higher burst incidence. CONCLUSION: Cardiovagal BRS indices have limited value in differentiating healthy and heart failure subjects. Incalculable values among patients indicate more severe disease state. BRSSY-incidence does separate healthy and diseased population, the missing BRSSY-incidence values are related to increased sympathetic activity. Orv Hetil. 2021; 162(3): 91-98.

Theory and history of the study of muscle sympathetic nerve activity / Az izom szimpatikus idegaktivitás vizsgálatának elméleti alapjai és története

Heart failure is a rapidly growing epidemic in developed countries. It has been well documented that heart failure is associated with abnormal neurohumoral activation. The autonomic regulation is characterized by decreased parasympathetic and elevated sympathetic activity. While the cardiovagal activity could be easily assessed by various heart rate variability parameters, markers of the sympathetic activity are not readily available. Percutaneous insertion of microelectrodes in a peripheral nerve allows recording of the muscle sympathetic vasomotor nerve activity (MSNA). MSNA shows good correlation with the cardiac sympathetic activity, and also with the levels of circulating catecholamines. Besides determination of the baseline sympathetic activity, rapid sympathetic responses to various stimuli can be also described by changes of MSNA. Elevated MSNA has been documented in several diseases, including hypertension, obesity, myocardial ischemia and renal failure. In heart failure, the elevated MSNA is well correlated to the clinical severity of the patient's conditions, and serves as a prognostic marker of mortality. In our paper, we give a short account of the history of MSNA studies, describe its physiological background and clinical relevance with special regard to heart failure. Orv Hetil. 2020; 161(29): 1190-1199.

Genotypic and phenotypic spectrum of the most common causative genes of Charcot-Marie-Tooth disease in Hungarian patients.

Charcot-Marie-Tooth neuropathy (CMT) is a genetically and clinically heterogeneous group of neuromuscular disorders with an overall prevalence of 1 per 2500. Here we report the first comprehensive genetic epidemiology study of Hungarian CMT patients. 409 CMT1 and 122 CMT2 patients were enrolled and genetic testing of PMP22, GJB1, MPZ, EGR2 and MFN2 genes were performed routinely. NDRG1 and CTDP1 genes were screened only for founder mutations in Roma patients. Causative genetic mutations were identified in 67.2% of the CMT1 and in 33.6% of the CMT2 cases, which indicates an overall success rate of 59.9% in the study population. Considering all affected individuals, alterations were most frequently found in PMP22 (40.5%), followed by GJB1 (9.2%), MPZ (4.5%), MFN2 (2.5%), NDRG1 (1.5%), EGR2 (0.8%) and CTDP1 (0.8%). The phenotypic spectrum and the disease severity of the studied patients also varied broadly. Deafness and autoimmune disorders were more often associated with PMP22 duplication, while MFN2 and GJB1 mutations were frequently present with central nervous system abnormalities. Our study may be helpful in determining the strategy of genetic diagnostics in Hungarian CMT patients.

Three novel mutations and genetic epidemiology analysis of the Gap Junction Beta 1 (GJB1) gene among Hungarian Charcot-Marie-Tooth disease patients.

Pathogenic variants of the gap junction beta 1 (GJB1) gene are responsible for the Charcot-Marie-Tooth neuropathy X type 1 (CMTX1). In this study, we report the mutation frequency of GJB1 in 210 Hungarian CMT patients and the phenotype comparison between male and female CMTX1 patients. Altogether, 13 missense substitutions were found in the GJB1 gene. Among them, 10 have been previously described as pathogenic variants (p.Arg15Trp, p.Val63Ile, p.Leu89Val, p.Ala96Gly, p.Arg107Trp, p.Arg142Gln, p.Arg164Trp, p.Arg164Gln, p.Pro172Ala and p.Asn205Ser), while 3 were novel, likely pathogenic alterations (p.Val13Glu, p.Glu186Gly, p.Met194Ile). These variants were not present in controls and were predicted as disease causing by in silico analysis. The frequency of the variants was 6.7% in our cohort which refers to a common cause of hereditary neuropathy among Hungarian patients. In addition to the classical phenotype, CNS involvement was proved in 26.1% of the CMTX1 patients. GJB1 pathogenic alterations were found mainly in males but we also detected them in female probands. The statistical analysis of CMTX1 patients revealed a significant difference between the two genders regarding the age of onset, Charcot-Marie-Tooth neuropathy and examination scores.

New perspectives in the renin-angiotensin-aldosterone system (RAAS) III: endogenous inhibition of angiotensin converting enzyme (ACE) provides protection against cardiovascular diseases.

ACE inhibitor drugs decrease mortality by up to one-fifth in cardiovascular patients. Surprisingly, there are reports dating back to 1979 suggesting the existence of endogenous ACE inhibitors. Here we investigated the clinical significance of this potential endogenous ACE inhibition. ACE concentration and activity was measured in patient's serum samples (n = 151). ACE concentration was found to be in a wide range (47-288 ng/mL). ACE activity decreased with the increasing concentration of the serum albumin (HSA): ACE activity was 56 ± 1 U/L in the presence of 2.4 ± 0.3 mg/mL HSA, compared to 39 ± 1 U/L in the presence of 12 ± 1 mg/mL HSA (values are mean ± SEM). Effects of the differences in ACE concentration were suppressed in human sera: patients with ACE DD genotype exhibited a 64% higher serum ACE concentration (range, 74-288 ng/mL, median, 155.2 ng/mL, n = 52) compared to patients with II genotype (range, 47-194 ng/mL, median, 94.5 ng/mL, n = 28) while the difference in ACE activities was only 32% (range, 27.3-59.8 U/L, median, 43.11 U/L, and range 15.6-55.4 U/L, median, 32.74 U/L, respectively) in the presence of 12 ± 1 mg/mL HSA. No correlations were found between serum ACE concentration (or genotype) and cardiovascular diseases, in accordance with the proposed suppressed physiological ACE activities by HSA (concentration in the sera of these patients: 48.5 ± 0.5 mg/mL) or other endogenous inhibitors. Main implications are that (1) physiological ACE activity can be stabilized at a low level by endogenous ACE inhibitors, such as HSA; (2) angiotensin II elimination may have a significant role in angiotensin II related pathologies.

New perspectives in the renin-angiotensin-aldosterone system (RAAS) I: endogenous angiotensin converting enzyme (ACE) inhibition.

Angiotensin-converting enzyme (ACE) inhibitors represent the fifth most often prescribed drugs. ACE inhibitors decrease 5-year mortality by approximately one-fifth in cardiovascular patients. Surprisingly, there are reports dating back to 1979 suggesting the existence of endogenous ACE inhibitors, which endogenous inhibitory effects are much less characterized than that for the clinically administered ACE inhibitors. Here we aimed to investigate this endogenous ACE inhibition in human sera. It was hypothesized that ACE activity is masked by an endogenous inhibitor, which dissociates from the ACE when its concentration decreases upon dilution. ACE activity was measured by FAPGG hydrolysis first. The specific (dilution corrected) enzyme activities significantly increased by dilution of human serum samples (23.2 ± 0.7 U/L at 4-fold dilution, 51.4 ± 0.3 U/L at 32-fold dilution, n = 3, p = 0.001), suggesting the presence of an endogenous inhibitor. In accordance, specific enzyme activities did not changed by dilution when purified renal ACE was used, where no endogenous inhibitor was present (655 ± 145 U/L, 605 ± 42 U/L, n = 3, p = 0.715, respectively). FAPGG conversion strongly correlated with angiotensin I conversion suggesting that this feature is not related to the artificial substrate. Serum samples were ultra-filtered to separate ACE (MW: 180 kDa) and the hypothesized inhibitor. Filtering through 50 kDa filters was without effect, while filtering through 100 kDa filters eliminated the inhibiting factor (ACE activity after <100 kDa filtering: 56.4 ± 2.4 U/L, n = 4, control: 26.4 ± 0.7 U/L, n = 4, p<0.001). Lineweaver-Burk plot indicated non-competitive inhibition of ACE by this endogenous factor. The endogenous inhibitor had higher potency on the C-terminal active site than N-terminal active site of ACE. Finally, this endogenous ACE inhibition was also present in mouse, donkey, goat, bovine sera besides men (increasing of specific ACE activity from 4-fold to 32-fold dilution: 2.8-fold, 1.7-fold, 1.5-fold, 1.8-fold, 2.6-fold, respectively). We report here the existence of an evolutionary conserved mechanism suppressing circulating ACE activity, in vivo, similarly to ACE inhibitory drugs.

New perspectives in the renin-angiotensin-aldosterone system (RAAS) II: albumin suppresses angiotensin converting enzyme (ACE) activity in human.

About 8% of the adult population is taking angiotensin-converting enzyme (ACE) inhibitors to treat cardiovascular disease including hypertension, myocardial infarction and heart failure. These drugs decrease mortality by up to one-fifth in these patients. We and others have reported previously that endogenous inhibitory substances suppress serum ACE activity, in vivo, similarly to the ACE inhibitor drugs. Here we have made an effort to identify this endogenous ACE inhibitor substance. ACE was crosslinked with interacting proteins in human sera. The crosslinked products were immunoprecipitated and subjected to Western blot. One of the crosslinked products was recognized by both anti-ACE and anti-HSA (human serum albumin) antibodies. Direct ACE-HSA interaction was confirmed by binding assays using purified ACE and HSA. HSA inhibited human purified (circulating) and human recombinant ACE with potencies (IC50) of 5.7 ± 0.7 and 9.5 ± 1.1 mg/mL, respectively. Effects of HSA on the tissue bound native ACE were tested on human saphenous vein samples. Angiotensin I evoked vasoconstriction was inhibited by HSA in this vascular tissue (maximal force with HSA: 6.14 ± 1.34 mN, without HSA: 13.54 ± 2.63 mN), while HSA was without effects on angiotensin II mediated constrictions (maximal force with HSA: 18.73 ± 2.17 mN, without HSA: 19.22 ± 3.50 mN). The main finding of this study is that HSA was identified as a potent physiological inhibitor of the ACE. The enzymatic activity of ACE appears to be almost completely suppressed by HSA when it is present in its physiological concentration. These data suggest that angiotensin I conversion is limited by low physiological ACE activities, in vivo.

Vanilloid receptor-1 (TRPV1) expression and function in the vasculature of the rat.

Transient receptor potential (TRP) cation channels are emerging in vascular biology. In particular, the expression of the capsaicin receptor (TRPV1) was reported in vascular smooth muscle cells. This study characterized the arteriolar TRPV1 function and expression in the rat. TRPV1 mRNA was expressed in various vascular beds. Six commercially available antibodies were tested for TRPV1 specificity. Two of them were specific (immunostaining was abolished by blocking peptides) for neuronal TRPV1 and one recognized vascular TRPV1. TRPV1 was expressed in blood vessels in the skeletal muscle, mesenteric and skin tissues, as well as in the aorta and carotid arteries. TRPV1 expression was found to be regulated at the level of individual blood vessels, where some vessels expressed, while others did not express TRPV1 in the same tissue sections. Capsaicin (a TRPV1 agonist) evoked constrictions in skeletal muscle arteries and in the carotid artery, but had no effect on the femoral and mesenteric arteries or the aorta. In blood vessels, TRPV1 expression was detected in most of the large arteries, but there were striking differences at level of the small arteries. TRPV1 activity was suppressed in some isolated arteries. This tightly regulated expression and function suggests a physiological role for vascular TRPV1.

Different desensitization patterns for sensory and vascular TRPV1 populations in the rat: expression, localization and functional consequences.

BACKGROUND AND PURPOSE: TRPV1 is expressed in sensory neurons and vascular smooth muscle cells, contributing to both pain perception and tissue blood distribution. Local desensitization of TRPV1 in sensory neurons by prolonged, high dose stimulation is re-engaged in clinical practice to achieve analgesia, but the effects of such treatments on the vascular TRPV1 are not known. EXPERIMENTAL APPROACH: Newborn rats were injected with capsaicin for five days. Sensory activation was measured by eye wiping tests and plasma extravasation. Isolated, pressurized skeletal muscle arterioles were used to characterize TRPV1 mediated vascular responses, while expression of TRPV1 was detected by immunohistochemistry. KEY RESULTS: Capsaicin evoked sensory responses, such as eye wiping (3.6±2.5 versus 15.5±1.4 wipes, p<0.01) or plasma extravasation (evans blue accumulation 10±3 versus 33±7 µg/g, p<0.05) were reduced in desensitized rats. In accordance, the number of TRPV1 positive sensory neurons in the dorsal root ganglia was also decreased. However, TRPV1 expression in smooth muscle cells was not affected by the treatment. There were no differences in the diameter (192±27 versus 194±8 µm), endothelium mediated dilations (evoked by acetylcholine), norepinephrine mediated constrictions, myogenic response and in the capsaicin evoked constrictions of arterioles isolated from skeletal muscle. CONCLUSION AND IMPLICATIONS: Systemic capsaicin treatment of juvenile rats evokes anatomical and functional disappearance of the TRPV1-expressing neuronal cells but does not affect the TRPV1-expressing cells of the arterioles, implicating different effects of TRPV1 stimulation on the viability of these cell types.

Vascular metabolism of anandamide to arachidonic acid affects myogenic constriction in response to intraluminal pressure elevation.

AIMS: We hypothesized that arachidonic acid produced by anandamide breakdown contributes to the vascular effects of anandamide. MAIN METHODS: Isolated, pressurized rat skeletal muscle arteries, which possess spontaneous myogenic tone, were treated with anandamide, arachidonic acid, capsaicin (vanilloid receptor agonist), WIN 55-212-2 (cannabinoid receptor agonist), URB-597 (FAAH inhibitor), baicalein (lipoxygenase inhibitor), PPOH (cytochrome P450 inhibitor), and indomethacin (cyclooxygenase inhibitor). Changes in the arteriolar diameter in response to the various treatments were measured. To assess the effect of anandamide metabolism, anandamide was applied for 20 min followed by washout for 40 min. This protocol was used to eliminate other, more direct effects of anandamide in order to reveal how anandamide metabolism may influence vasodilation. KEY FINDINGS: Anandamide at a low dose (1µM) evoked a loss of myogenic tone, while a high dose (30 µM) not only attenuated the myogenic response but also evoked acute dilation. Both of these effects were inhibited by the FAAH inhibitor URB-597 and were mimicked by arachidonic acid. The CB1 and CB2 agonist R-WIN 55-212-2 and the vanilloid receptor agonist capsaicin were without effect on the myogenic response. The inhibition of the myogenic response by anandamide was blocked by indomethacin and PPOH, but not by baicalein or removal of the endothelium. FAAH expression in the smooth muscle cells of the blood vessels was confirmed by immunohistochemistry. SIGNIFICANCE: Anandamide activates the arachidonic acid pathway in the microvasculature, affecting vascular autoregulation (myogenic response) and local perfusion.

[Therapy for anti-MuSK antibody positive myasthenia gravis]. / A MuSK-ellenes antitest pozitív myasthenia gravis kezelése.

The authors report the case of a 27-year-old woman with muscle-specific receptor tyrosine kinase antibody positive myasthenia with predominantly ocular and bulbar symptoms. Both edrophonium and low dose (4×30 mg/day) pyridostigmin resulted in cholinergic side effects including fasciculation mainly in the facial and neck muscles, and excessive salivation. The patient responded well to a relatively high dose of chronic corticosteroid treatment (methyprednisolone 64mg/day), but the decrease of the corticosteroid dose below 16 mg/day induced exacerbation of the clinical symptoms. Immunosuppression with azathioprine and methotrexate failed to maintain the clinical improvement. However, plasma exchange was always very effective, and all clinical symptoms improved significantly. The authors conclude that patients with muscle-specific receptor tyrosine kinase antibody positive myasthenia gravis should have an individual treatment protocol differing from those used in patients who do not have this antibody but are positive for acetylcholine-receptor antibody. Identification of the pathogenic antibody in the early stage of myasthenia gravis may help to develop the optimal, individualized treatment strategy, to avoid severe side effects, and to achieve fast improvement.

Anandamide and the vanilloid receptor (TRPV1).

Arachidonylethanolamide (anandamide) was identified some 15 years ago as a brain constituent that binds to the cannabinoid receptor. After this seminal discovery, multiple new receptors for anandamide have been identified, including the vanilloid receptor (TRPV1), and anandamide is now frequently referred as an "endovanilloid." Characterization of the action of anandamide on TRPV1 revealed that (1) the potency and efficacy of anandamide on TRPV1 very much depend on the species and tissue, (2) anandamide responsiveness in vivo is significantly controlled by its local metabolism, (3) anandamide activation of cannabinoid receptors regulates TRPV1 responsiveness, (4) TRPV1 activation regulates anandamide synthesis, (5) anandamide metabolites affect TRPV1 responses, (6) the often observed convergent physiological actions of anandamide and TRPV1 agonists in neither case necessarily represent direct effects on TRPV1, and (7) coactivation of the cannabinoid receptors and TRPV1 often complicates the distinction between these pathways. These issues are reviewed here together with the potential implications for the pathophysiological and pharmacological regulation of inflammatory, respiratory, and cardiovascular disorders, as well as of appetite and fat metabolism.

Expression and distribution of vanilloid receptor 1 (TRPV1) in the adult rat brain.

The vanilloid receptor (TRPV1 or VR1) is a molecular integrator of various painful stimuli, including capsaicin, acid, and high temperature. It can also be activated by endogenous ligands, like the cannabinoid 1 receptor (CB1) agonist anandamide. TRPV1 is well characterized at the terminals of sensory nerves involved in the pain pathway. There is also evidence that TRPV1 is expressed in the brain but little is known about its function. Here, using commercially available specific antibodies to investigate the localization of TRPV1 in the brain of the rat, we report that TRPV1 was expressed in hippocampus, cortex, cerebellum, olfactory bulb, mesencephalon and hindbrain. Immunohistochemical analyses showed high expression in the cell bodies and dendrites of neurons in the hippocampus and in the cortex. To address the question of subcellular localization, immunoelectronmicroscopy was used. TRPV1-like staining was detected in the synapses (mostly, but not exclusively in post-synaptic dendritic spines), on the end feet of astrocytes and in pericytes. In summary, TRPV1 expression shows wide distribution in the brain of the rat, being found in astrocytes and pericytes as well as in neurons. Its localization is consistent with multiple functions within the central nervous system, including the regulation of brain vasculature.