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Key pointsr Two-pore channels (TPCs) were identified as a novel family of endolysosome-targeted calcium release channels gated by nicotinic acid adenine dinucleotide phosphate, as also as intracellular Na + channels able to control endolysosomal fusion, a key process in autophagic flux.r Autophagy, an evolutionarily ancient response to cellular stress, has been implicated in the pathogenesis of a wide range of cardiovascular pathologies, including heart failure.r We report direct evidence indicating that TPCs are involved in regulating autophagy in cardiomyocytes, and that TPC knockout mice show alterations in the cardiac lysosomal system. TPC downregulation implies a decrease in the viability of cardiomyocytes under starvation conditions. In cardiac tissues from both humans and rats, TPC transcripts and protein levels were higher in females than in males, and correlated negatively with markers of autophagy.r We conclude that the endolysosomal channels TPC1 and TPC2 are essential for appropriate basal and induced autophagic flux in cardiomyocytes, and also that they are differentially expressed in male and female hearts.Abstract Autophagy participates in physiological and pathological remodelling of the heart. The endolysosomal two-pore channels (TPCs), TPC1 and TPC2, have been implicated in the regulation of autophagy. The present study aimed to investigate the role of TPC1 and TPC2 in basal and induced cardiac autophagic activity. In cultured cardiomyocytes, starvation induced a significant increase in TPC1 and TPC2 transcripts and protein levels that paralleled the increase in autophagy identified by increased LC3-II and decreased p62 levels. Small interfering RNA depletion of TPC2 alone or together with TPC1 increased both LC3II and p62 levels under basal conditions and in response to serum starvation, suggesting that, under conditions of severe energy depletion (serum plus glucose starvation), changes in the autophagic flux (as assessed by use of bafilomycin A1) occurred either when TPC1 or TPC2 were downregulated. The knockdown of TPCs diminished cardiomyocyte viability under starvation and simulated ischaemia. Electron micrographs of hearts from TPC1/2 double knockout mice showed that cardiomyocytes contained large numbers of immature lysosomes with diameters significantly smaller than those of wild-type mice. In cardiac tissues from humans and rats, TPC1 and TPC2 transcripts and protein levels were higher in females than in males. Furthermore, transcript levels of TPCs correlated negatively with p62 levels in heart tissues. TPC1 and TPC2 are essential for appropriate basal and induced autophagic flux in cardiomyocytes (i.e. there is a negative effect on cell viability under stress conditions in their absence) and they are differentially expressed in male and female human and murine hearts, where they correlate with markers of autophagy.

Background: Plasma NT-proBNP levels are sensitive markers of ventricular dysfunction. However, studies of natriuretic peptides in urine are limited. Aims: To compare urine and plasma NT-proBNP levels and to investigate the diagnostic and prognostic value of urine levels in heart failure (HF). Methods: Urinary and plasma NT-proBNP levels were measured in 96 HF patients and 20 control subjects. The patients were functionally classified according to the NYHA criteria. Results: Urine NT-proBNP was higher in HF patients than in control subjects (94 T 31 pg/ml vs. 67 T 6 pg/ml, p < 0.0001), correlating with plasma NT-proBNP levels (r = 0.78, p < 0.0001). Urinary levels were elevated in the more severe functional classes and diminished in obese patients. Urine NT-proBNP was a good tool for diagnosis of HF, the area under the curve (AUC) being 0.96 T 0.02 ( p < 0.0001), and for predicting 12-month cardiac events ( p = 0.011). To determine the prognostic power of urinary NT-proBNP in detecting 12-month cardiac mortality, we obtained an AUC of 0.75 T 0.10 ( p = 0.015). Conclusion: Urinary NT-proBNP, a relatively simple non-invasive test, is a new candidate marker for the diagnosis and evaluation of prognosis in HF and for the characterization of functional status in these patients.