Transient receptor potential canonical (TRPC) Ca 2+ -permeant channels, especially TRPC3, are increasingly implicated in cardiorenal diseases. We studied the possible role of fibroblast TRPC3 in the development of renal fibrosis. In vitro, a macromolecular complex formed by TRPC1/TRPC3/TRPC6 existed in isolated cultured rat renal fibroblasts. However, specific blockade of TRPC3 with the pharmacologic inhibitor pyr3 was sufficient to inhibit both angiotensin II-and 1-oleoyl-2-acetyl-sn-glycerol-induced Ca 2+ entry in these cells, which was detected by fura-2 Ca 2+ imaging. TRPC3 blockade or Ca 2+ removal inhibited fibroblast proliferation and myofibroblast differentiation by suppressing the phosphorylation of extracellular signalregulated kinase (ERK1/2). In addition, pyr3 inhibited fibrosis and inflammation-associated markers in a noncytotoxic manner. Furthermore, TRPC3 knockdown by siRNA confirmed these pharmacologic findings. In adult male Wistar rats or wild-type mice subjected to unilateral ureteral obstruction, TRPC3 expression increased in the fibroblasts of obstructed kidneys and was associated with increased Ca 2+ entry, ERK1/2 phosphorylation, and fibroblast proliferation. Both TRPC3 blockade in rats and TRPC3 knockout in mice inhibited ERK1/2 phosphorylation and fibroblast activation as well as myofibroblast differentiation and extracellular matrix remodeling in obstructed kidneys, thus ameliorating tubulointerstitial damage and renal fibrosis. In conclusion, TRPC3 channels are present in renal fibroblasts and control fibroblast proliferation, differentiation, and activation through Ca 2+ -mediated ERK signaling. TRPC3 channels might constitute important therapeutic targets for improving renal remodeling in kidney disease.

The aim of this work is to evaluate the impact on the rat microbiota of long-term feeding with phenolic compounds (PC) rich grape pomace extracts. Thirty, 2-mo-old rats, were divided into 5 groups. Four groups were treated with different concentrations of PC (2.5, 5, 10, and 20 mg/kg/d diluted in 0.1% DMSO), and 1 group received 0.1% Dimethyl Sulfoxide (DMSO) alone (control group). The daily treatment lasted 14 mo. Major phenolic compounds constituents were characterized by the high-performance liquid chromatography and free radical scavenging capacity was measured by means of the DPPH assay. Fecal samples from young rats (2-mo old), and rats daily fed with PC or DMSO were collected at 6 and 14 mo posttreatment. The gut microbiota composition was analyzed by quantitative polymerase chain reaction. Bifidobacterium was significantly higher in the groups PC 2.5 and PC 5 than in control and young rats. Lactobacillus decreased with time in all treated and untreated groups. Bacteroides, Clostridium leptum subgroup (Clostridium cluster IV), and Enterococcus were not significantly changed by PC at any concentration when compared to control; nevertheless, after 14 mo of treatment all concentrations of PC abolished the increase of Clostridium sensu stricto (cluster I) (Clostridium Cluster I) observed in the control group when compared to young rats. PC do modulate selectively rat gut microbiome to a healthier phenotype in long-term feeding rats, and could counteract the adverse outcomes of aging on gut bacterial population.Keywords: aging, gut microbiota, phenolic compoundsPractical Application: This research shows that phenolic-rich grape pomace extracts exhibiting a high antioxidant activity, selectively modulate rat gut microbiota to a healthier phenotype within age in a long-term feeding rats.

The presence of a hyperpolarization‐activated pacemaker (If)‐like current was tested in dedifferentiated adult rat ventricular myocytes up to 12 days in primary culture with the whole‐cell patch clamp technique. An If‐like current was found and characterized on freshly isolated and cultured ventricular cells. Both activation and density of the current varied in relation to the stage of dedifferentiation. The current was activated from ‐92.0 ± 2.5 and ‐63.0 ± 1.0 mV at the beginning (4‐day‐cultured cells) and end of the dedifferentiation process (12 days), respectively. Its density measured at ‐170 mV progressively increased from ‐2.34 ± 0.36 to ‐6.12 ± 0.64 pA pF−1 between the two farthest stages of cellular remodelling. In freshly isolated cells the current was activated at ‐108.0 ± 1.5 mV and its current density measured at ‐170 mV was ‐1.97 ± 0.56 pA pF−1. The current was blocked by extracellular CsCl (3 mM) in a voltage‐dependent manner. Modification of reversal potentials obtained at various values of [K+]o (5.4 or 25 mM) and [Na+]o (140 or 30 mM) suggests that the current was carried by both K+ and Na+ ions. It is concluded that the hyperpolarization‐activated inward current, recorded in freshly isolated and in cultured ventricular cells has characteristics similar to those of If. In adult rat ventricular cells it is activated in a non‐physiological potential range, but can be elicited in a more physiological range when the cells are remodelled through a dedifferentiated way. It is suggested that such a current could be implicated in ventricular arrhythmias developed in pathological events.

Cardiac Orai3 is the essential partner of STIM1 and drives voltage-independent Ca(2+) entries in adult cardiomyocytes. Arachidonic acid-activated currents, which are supported by Orai3, are present in adult cardiomyocytes and increased during hypertrophy.