AimThe aim of the study was to compare the functional and structural properties of the motor protein, myosin, and isolated myocyte contractility in heart muscle excised from hypertrophic cardiomyopathy patients by surgical myectomy with explanted failing heart and non-failing donor heart muscle.MethodsMyosin was isolated and studied using an in vitro motility assay. The distribution of myosin light chain-1 isoforms was measured by two-dimensional electrophoresis. Myosin light chain-2 phosphorylation was measured by sodium dodecyl sulphate–polyacrylamide gel electrophoresis using Pro-Q Diamond phosphoprotein stain.ResultsThe fraction of actin filaments moving when powered by myectomy myosin was 21% less than with donor myosin (P = 0.006), whereas the sliding speed was not different (0.310 ± 0.034 for myectomy myosin vs. 0.305 ± 0.019 µm/s for donor myosin in six paired experiments). Failing heart myosin showed 18% reduced motility. One myectomy myosin sample produced a consistently higher sliding speed than donor heart myosin and was identified with a disease-causing heavy chain mutation (V606M). In myectomy myosin, the level of atrial light chain-1 relative to ventricular light chain-1 was 20 ± 5% compared with 11 ± 5% in donor heart myosin and the level of myosin light chain-2 phosphorylation was decreased by 30–45%. Isolated cardiomyocytes showed reduced contraction amplitude (1.61 ± 0.25 vs. 3.58 ± 0.40%) and reduced relaxation rates compared with donor myocytes (TT50% = 0.32 ± 0.09 vs. 0.17 ± 0.02 s).ConclusionContractility in myectomy samples resembles the hypocontractile phenotype found in end-stage failing heart muscle irrespective of the primary stimulus, and this phenotype is not a direct effect of the hypertrophy-inducing mutation. The presence of a myosin heavy chain mutation causing hypertrophic cardiomyopathy can be predicted from a simple functional assay.

Advertisement calls of males from two Spanish populations of parsley frogs (Pelodytes punctatus) were recorded. Body size (SVL, mass) and calling temperature were measured, and age was determined through skeletochronolog y of phalanges . Calling males were 2-7 years old in Valencia. In Burgos, males were 1-6 years old and the age structure was highly skewed with more than 50% of the sample of males being 1 year old. The range of body temperatures of calling males was similar in both sites (10-15.1 ± C in Valencia, and 10-17.5 ± C in Burgos). Males called with the typical two-note advertisement call A-B, although in Burgos it was common to hear A-only calls. In both populations repetition of the second note was rare. Calls of both populations showed a negative correlation between temporal parameters (note duration, inter-note interval, pulse rate) and body temperature. On the other hand, spectral parameters (dominant frequencies and dominant frequency ranges) were not correlated to temperature and correlation with body size (SVL, mass) was non-signi cant. Age was not signi cantly correlated with dominant frequency or with any other measured call parameter. Call frequency in Pelodytes is a poor predictor of male body size and does not convey information on age. Thus, any size-related mating trends could result from non-static calling parameters such as call intensity, or from mechanisms of malemale competition (e.g. chorus attendance).

Background and Purpose: Cellular Communication Network Factor 2 (CCN2) is a matricellular protein normally present in the vascular wall but overexpressed in several cardiovascular diseases. CCN2 has been proposed as a downstream mediator of profibrotic actions of Transforming Growth Factor (TGF)-β and Angiotensin II (Ang II). However, its direct role in cardiovascular diseases is not completely understood. Experimental Approach: To investigate the direct role of CCN2 under vascular pathological conditions, a conditionally deficient CCN2 (CCN2-KO) mouse was evaluated infused or not with Ang II. Key Results: In the absence of CCN2, Ang II infusion induced a rapid (within 48 hours) aortic aneurysm generation and increased aneurysm rupture with 80 % lethality at the endpoint. CCN2 deletion caused elastin layer disruption and increased metalloproteinase activity, which were aggravated by Ang II administration. Aortic RNA-seq studies and the subsequent Gene Ontology enriched analysis pointed out the aldosterone biosynthesis process as one of the most enriched terms in absence of CCN2. Pharmacological aldosterone pathway intervention in Ang II-infused CCN2-KO mice, by treatment with the mineralocorticoid receptor antagonist spironolactone, reduced aneurysm formation and mortality after Ang II infusion. Conclusion and Implications: CCN2 deletion induces a rapid aneurysm formation and rupture after Ang II infusion which is partially prevented by blocking the mineralocorticoid receptor. Our present data highlight, for the first time, the potential role of CCN2 as a vascular homeostatic factor and its relevance in the aldosterone synthesis, opening new avenues to future studies in aortic aneurysm treatment.