Cardiovascular diseases, including coronary artery disease, ischemic heart diseases such as acute myocardial infarction and postischemic heart failure, heart failure of other etiologies, and cardiac arrhythmias, belong to the leading causes of death. Activation of capsaicin-sensitive sensory nerves by the transient receptor potential vanilloid 1 (TRPV1) capsaicin receptor and other receptors, as well as neuropeptide mediators released from them upon stimulation, play important physiological regulatory roles. Capsaicin-sensitive sensory nerves also contribute to the development and progression of some cardiac diseases, as well as to mechanisms of endogenous stress adaptation leading to cardioprotection. In this review, we summarize the role of capsaicin-sensitive afferents and the TRPV1 ion channel in physiological and pathophysiological functions of the heart based mainly on experimental results and show their diagnostic or therapeutic potentials. Although the actions of several other channels or receptors expressed on cardiac sensory afferents and the effects of TRPV1 channel activation on different non-neural cell types in the heart are not precisely known, most data suggest that stimulation of the TRPV1-expressing sensory nerves or stimulation/overexpression of TRPV1 channels have beneficial effects in cardiac diseases.

Background: We recently developed novel matrix metalloproteinase-2 (MMP-2) inhibitor small molecules for cardioprotection against ischemia/reperfusion injury and validated their efficacy in ischemia/reperfusion injury in cardiac myocytes. The aim of the present study was to test our lead compounds for cardioprotection in vivo in a rat model of acute myocardial infarction (AMI) in the presence or absence of hypercholesterolemia, one of the major comorbidities affecting cardioprotection. Methods: Normocholesterolemic adult male Wistar rats were subjected to 30 min of coronary occlusion followed by 120 min of reperfusion to induce AMI. MMP inhibitors (MMPI)-1154 and -1260 at 0.3, 1, and 3 µmol/kg, MMPI-1248 at 1, 3, and 10 µmol/kg were administered at the 25th min of ischemia intravenously. In separate groups, hypercholesterolemia was induced by a 12-week diet (2% cholesterol, 0.25% cholic acid), then the rats were subjected to the same AMI protocol and single doses of the MMPIs that showed the most efficacy in normocholesterolemic animals were tested in the hypercholesterolemic animals. Infarct size/area at risk was assessed at the end of reperfusion in all groups by standard Evans blue and 2,3,5-triphenyltetrazolium chloride (TTC) staining, and myocardial microvascular obstruction (MVO) was determined by thioflavine-S staining. Results: MMPI-1154 at 1 µmol/kg, MMPI-1260 at 3 µmol/kg and ischemic preconditioning (IPC) as the positive control reduced infarct size significantly; however, this effect was not seen in hypercholesterolemic animals. MVO in hypercholesterolemic animals decreased by IPC only. Conclusions: This is the first demonstration that MMPI-1154 and MMPI-1260 showed a dose-dependent infarct size reduction in an in vivo rat AMI model; however, single doses that showed the most efficacy in normocholesterolemic animals were abolished by hypercholesterolemia. The further development of these promising cardioprotective MMPIs should be continued with different dose ranges in the study of hypercholesterolemia and other comorbidities.

During the last decades, mortality from acute myocardial infarction has been dramatically reduced. However, the incidence of post-infarction heart failure is still increasing. Cardioprotection by ischaemic conditioning had been discovered more than three decades ago. Its clinical translation, however, is still an unmet need. This is mainly due to the disrupted cardioprotective signalling pathways in the presence of different cardiovascular risk factors, co-morbidities and the medication being taken. Sensory neuropathy is one of the co-morbidities that has been shown to interfere with cardioprotection. In the present review, we summarize the diverse aetiology of sensory neuropathies and the mechanisms by which these neuropathies may interfere with ischaemic heart disease and cardioprotective signalling. Finally, we suggest future therapeutic options targeting both ischaemic heart and sensory neuropathy simultaneously.

Fumaric acid, fumaric acid dimethylester, and the dithranol derivative C4-lactone were studied in the mouse tail test to evaluate their effects on epidermal cell differentiation compared with other topical antipsoriatic drugs, such as betamethasone, calcipotriol, and dithranol. Mouse tails were treated for 2 weeks and longitudinal histological sections prepared of the tail skin. The length of the orthokeratotic regions (stratum granulosum) was measured on 10 sequential scales per tail and expressed as percentage of the full length of the scale. In addition, epidermal thickness was measured and the efficacy of the various compounds evaluated. In comparison to 2% salicylic acid ointment, all tested compounds except fumaric acid significantly (p ≤ 0.05) increased the proportion of the orthokeratotic region. C4-lactone and calcipotriol were less effective than dithranol, fumaric acid dimethylester only moderately influenced cell differentiation, and betamethasone showed the least potent effect. Dithranol was the most potent substance inducing orthokeratosis without increasing epidermal thickness.

Purpose Matrix metalloproteinases (MMPs) are identified as modulators of the extracellular matrix in heart failure progression. However, evidence for intracellular effects of MMPs is emerging. Pro- and anti-hypertrophic cardiac effects are described. This may be due to the various sources of different MMPs in the heart tissue. Therefore, the aim of the present study was to determine the role of MMPs in hypertrophic growth of isolated rat ventricular cardiac myocytes. Methods Cardiomyocytes were isolated form ventricular tissues of the rat hearts by collagenase perfusion. RT-qPCR, western blots, and zymography were used for expression and MMP activity analysis. Cross-sectional area and the rate of protein synthesis were determined as parameters for hypertrophic growth. Results MMP-1, MMP-2, MMP-3, MMP-9 and MMP-14 mRNAs were detected in cardiomyocytes, and protein expression of MMP-2, MMP-9, and MMP-14 was identified. Hypertrophic stimulation of cardiomyocytes did not enhance, but interestingly decreased expression of MMPs, indicating that downregulation of MMPs may promote hypertrophic growth. Indeed, the nonselective MMP inhibitors TAPI-0 or TIMP2 and the MMP-2-selective ARP-100 enhanced hypertrophic growth. Furthermore, TAPI-0 increased phosphorylation and thus activation of extracellular signaling kinase (ERK) and Akt (protein kinase B), as well as inhibition of glycogen synthase 3β (GSK3β). Abrogation of MEK/ERK- or phosphatidylinositol-3-kinase(PI3K)/Akt/GSK3β-signaling with PD98059 or LY290042, respectively, inhibited hypertrophic growth under TAPI-0. Conclusion MMPs’ inhibition promotes hypertrophic growth in cardiomyocytes in vitro. Therefore, MMPs in the healthy heart may be important players to repress cardiac hypertrophy.

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Aims Remote ischemic preconditioning (RIPC) is a robust cardioprotective intervention in preclinical studies. To establish a working and efficacious RIPC protocol in our laboratories, we performed randomized, blinded in vivo studies in three study centres in rats, with various RIPC protocols. To verify that our experimental settings are in good alignment with in vivo rat studies showing cardioprotection by limb RIPC, we performed a systematic review and meta-analysis. In addition, we investigated the importance of different study parameters. Methods and Results Male Wistar rats were subjected to 20 to 45 min cardiac ischemia followed by 120 min reperfusion with or without preceding RIPC by 3 or 4×5-5 min occlusion/reperfusion of one or two femoral vessels by clamping, tourniquet, or pressure cuff. RIPC did not reduce IS, microvascular obstruction, or arrhythmias at any study centres. Systematic review and meta-analysis focusing on in vivo rat models of myocardial ischemia/reperfusion injury with limb RIPC showed that RIPC reduces IS by 21.28% on average. In addition, the systematic review showed methodological heterogeneity and insufficient reporting of study parameters in a high proportion of studies. Conclusion We report for the first time the lack of cardioprotection by RIPC in rats, assessed in individually randomized, blinded in vivo studies, involving three study centres, using different RIPC protocols. These results are in discrepancy with the meta-analysis of similar in vivo rat studies, however, no specific methodological reason could be identified by systematic review, probably due to the overall insufficient reporting of several study parameters that did not improve over the past two decades. These results urge for publication of more well-designed and well-reported studies, irrespective of the outcome, which are required for preclinical reproducibility, and the development of clinically translatable cardioprotective interventions.